IZZAT Angiosperma

8/14/2019 IZZAT Angiosperma

1/17

Flowering Plants or Angiospermae [phylum] are the dominant plants on

earth at this time and have been for the last 100 million years. Traditionally theyhave been divided into two divisions [classes] called onocotyledons [one seed!

leaf] and "icotyledons [# seed leaves] based on the number of food stores

contained in the seeds. onocots also have parallel venation while the others havecomple$ netted venation.

Apart from some other structural features of importance% the classification of

Angiosperms rests mostly upon the structure of the flower% which is undoubtedlytheir most distinctive feature. This is mainly because it is the flower which shows

such remar&able plasticity of form. This variability of the structure of the flower inturn reflects the intimate adaptive association of flowers with insects% whose

evolution they have closely paralleled. 'ndeed% such a phenomenon is often given as

an e$ample of co!evolution because of the strength and longevity of the contact

between the two groups% and the diverse ways they have mutually influenced eachother in structure and in life!cycles.

("uring the first )0 million years of angiospermous evolution all the &nown flowers

were radially symmetrical. 't is only in the Tertiary *++., to 1.+ million years ago- during the

late Paleocene and early ocene *+/.+ to # million years ago- that the first evidence of

bilaterally symmetrical flowers is found. The evolution of bilateral flowers% as% for e$ample%

those of the legumes and orchids% is an adaptation for specialied pollinators such as social

insects *bees- and some birds. The sterile organs *sepals% petals- are modified to present a

certain flower orientation to the pollinator% enabling the pollinator to enter the flower where

the pollen organs and pollen!receptive tissue are positioned to ma$imie effective pollination.

"uring the early Tertiary% the bilateral organiation of floral organs coevolved with animalbehaviour independently at different times and in various groups of angiosperms.(

[ncyclopedia 2rittanica]

There is within the Angiosperms a general trend from primitive beetle andfly pollinated flowers towards more advanced pollination by butterflies% moths and

bees. Flowers pollinated by bees show the greatest degree of nectar% scent%

coloration diversity and pollen production% as well as diverse specialisation of

flower structure. Primitive flowers tend to be trumpet or saucer shaped [e$amples

includeRanunculus, Hibiscus, Magnolia, Malva, Lavatera, Cucurbita and

Papaver]% while more advanced flowers maybe tubular [e$amples li&e Symphytum,Digitalis, Lamium, Erica, Datura andNicotiana]% or ygomorphic. $amples of the

latter include Orchis, ntirrhiunum, Pisum, Lobelia, !iola, "entiana, #isteria,Mimulus, Loniceraand$egonia. There are thus two directions of adaptation3 from

polypetaly [many petals] to oligopetaly [fewer petals] and from separate petals to

sympetaly [fused petals]

4owever% simple flowers% as in Commelinidae[5rasses% 6edges and 7ushes

and Euphorbiales] may not be primitive% but derived from more comple$ forms in

the Liliales. This% their simplicity is secondary and a form of structural degeneracyrather than a primitive feature.


2/17

Another important trend is away from single flowers [li&e Papaver,

Ranunculus, Nelumbo] towards multiple flowers in racemes% spi&es% whorls% andheads [eg.Lamium, Scrophularia, "enitaiana, $orago, Laburnum, Plantago,

chillea, Sali%]. This trend reaches its height of perfection in the Dipsacales% the

Umbelliferae [Apiales]and above all in the Asterales. The Asteraceaecompoundflowers are really a spi&e or whorl of flowers that has failed to e$pand vertically

and all the flowers are pac&ed side by side instead on a flat head [capitulum]. 8ou

can still trace the spiral patterns inHelianthusheads% for e$ample% where the whorl!li&e pattern of the raceme would have unfolded if it had elongated vertically.

The inflorescence of daisies therefore give the appearance of a raceme thathas been compressed downwards forcing all the individual flowers to become

pressed tightly into a side by side arangement on a flat head [e.g.$ellis, chillea].

The dome shape of the Dipsacales flowers is similar% li&e an early version of this

arrangement% but in the umbels of the Umbelliferaeeach individual flower stillretains its own separate stal& and bracts.

The flowering plants*angiosperms-% also &nown as Angiospermaeor Magnoliophyta% are

the most diverse group ofland plants. Angiosperms areseed!producing plantsli&e the

gymnospermsand can be distinguished from the gymnosperms by a series ofsynapomorphies

*derived characteristics-. These characteristics include flowers% endospermwithin the seeds%

and the production of fruitsthat contain the seeds.

The ancestors of flowering plants diverged from gymnospermsaround #,9#0# million years

ago% and the first flowering plants &nown to e$ist are from 1,0 million years ago. They

diversified enormously during the :ower ;retaceousand became widespread around 100

million years ago% but replaced conifersas the dominant trees only around +0!100 million

years ago.

Angiosperm derived characteristics

Flowers

The flowers% which are the reproductive organsof flowering plants% are the most remar&ablefeature distinguishing them from other seed plants. Flowers aid angiosperms by enabling a

wider range of adaptability and broadening theecological nichesopen to them. This has

allowed flowering plants to largely dominateterrestrialecosystems.

6tamens with two pairs of pollen sacs

6tamens are much lighter than the corresponding organs of gymnosperms and have

contributed to the diversification of angiosperms through time with adaptationsto specialied

pollinationsyndromes% such as particular pollinators. 6tamens have also become modified

through time to prevent self!fertiliation%which has permitted further diversification% allowing

angiosperms eventually to fill more niches.
http://en.wikipedia.org/wiki/Embryophyteshttp://en.wikipedia.org/wiki/Embryophyteshttp://en.wikipedia.org/wiki/Spermatophytehttp://en.wikipedia.org/wiki/Spermatophytehttp://en.wikipedia.org/wiki/Gymnospermhttp://en.wikipedia.org/wiki/Gymnospermhttp://en.wikipedia.org/wiki/Synapomorphyhttp://en.wikipedia.org/wiki/Synapomorphyhttp://en.wikipedia.org/wiki/Character_(biology)http://en.wikipedia.org/wiki/Flowerhttp://en.wikipedia.org/wiki/Endospermhttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Gymnospermshttp://en.wikipedia.org/wiki/Lower_Cretaceoushttp://en.wikipedia.org/wiki/Coniferhttp://en.wikipedia.org/wiki/Flowerhttp://en.wikipedia.org/wiki/Reproductive_organhttp://en.wikipedia.org/wiki/Ecological_nichehttp://en.wikipedia.org/wiki/Ecological_nichehttp://en.wikipedia.org/wiki/Terrestrial_ecoregionhttp://en.wikipedia.org/wiki/Terrestrial_ecoregionhttp://en.wikipedia.org/wiki/Stamenhttp://en.wikipedia.org/wiki/Adaptationhttp://en.wikipedia.org/wiki/Pollinationhttp://en.wikipedia.org/wiki/Self-fertilizationhttp://en.wikipedia.org/wiki/Self-fertilizationhttp://en.wikipedia.org/wiki/Embryophyteshttp://en.wikipedia.org/wiki/Spermatophytehttp://en.wikipedia.org/wiki/Gymnospermhttp://en.wikipedia.org/wiki/Synapomorphyhttp://en.wikipedia.org/wiki/Character_(biology)http://en.wikipedia.org/wiki/Flowerhttp://en.wikipedia.org/wiki/Endospermhttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Gymnospermshttp://en.wikipedia.org/wiki/Lower_Cretaceoushttp://en.wikipedia.org/wiki/Coniferhttp://en.wikipedia.org/wiki/Flowerhttp://en.wikipedia.org/wiki/Reproductive_organhttp://en.wikipedia.org/wiki/Ecological_nichehttp://en.wikipedia.org/wiki/Terrestrial_ecoregionhttp://en.wikipedia.org/wiki/Stamenhttp://en.wikipedia.org/wiki/Adaptationhttp://en.wikipedia.org/wiki/Pollinationhttp://en.wikipedia.org/wiki/Self-fertilization


3/17

7educed male parts% three cells

The male gametophytein angiosperms is significantly reduced in sie compared to those of

gymnosperm seed plants. The smaller pollen decreases the time from pollination < the pollen

grain reaching the female plant < tofertiliationof the ovary= in gymnosperms fertiliation

can occur up to a year after pollination% while in angiosperms the fertiliation begins verysoon after pollination. The shorter time leads to angiosperm plants setting seeds sooner and

faster than gymnosperms% which is a distinct evolutionary advantage.

;losed carpelenclosing the ovules *carpel or carpels and accessory parts may become

thefruit-

The closed carpel of angiosperms also allows adaptations to specialied pollination

syndromes and controls. This helps to prevent self!fertiliation% thereby maintaining increased

diversity. >nce the ovary is fertilied% the carpel and some surrounding tissues develop into a

fruit. This fruit often serves as an attractant to seed!dispersing animals. The resulting

cooperative relationship presents another advantage to angiosperms in the process ofdispersal.

7educed female gametophyte% seven cells with eight nuclei

The reduced female gametophyte% li&e the reduced male gametophyte% may be an adaptation

allowing for more rapid seed set% eventually leading to such flowering plant adaptations as

annual herbaceous life cycles% allowing the flowering plants to fill even more niches.

ndosperm

ndosperm formation generally begins after fertiliation and before the first division of the

ygote. ndosperm is a highly nutritive tissue that can provide food for the developing

embryo% the cotyledons% and sometimes for theseedlingwhen it first appears.

These distinguishing characteristics ta&en together have made the angiosperms the most

diverse and numerous land plants and the most commercially important group to humans. The

ma?or e$ception to the dominance of terrestrial ecosystems by flowering plants is the

coniferous forest.

Evolution

Further information3 volutionary history of plants@Flowers
http://en.wikipedia.org/wiki/Gametophytehttp://en.wikipedia.org/wiki/Fertilizationhttp://en.wikipedia.org/wiki/Fertilizationhttp://en.wikipedia.org/wiki/Carpelhttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Biological_dispersalhttp://en.wikipedia.org/wiki/Endospermhttp://en.wikipedia.org/wiki/Zygotehttp://en.wikipedia.org/wiki/Embryohttp://en.wikipedia.org/wiki/Seedlinghttp://en.wikipedia.org/wiki/Seedlinghttp://en.wikipedia.org/wiki/Coniferous_foresthttp://en.wikipedia.org/wiki/Evolutionary_history_of_plants#Flowershttp://en.wikipedia.org/wiki/Gametophytehttp://en.wikipedia.org/wiki/Fertilizationhttp://en.wikipedia.org/wiki/Carpelhttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Biological_dispersalhttp://en.wikipedia.org/wiki/Endospermhttp://en.wikipedia.org/wiki/Zygotehttp://en.wikipedia.org/wiki/Embryohttp://en.wikipedia.org/wiki/Seedlinghttp://en.wikipedia.org/wiki/Coniferous_foresthttp://en.wikipedia.org/wiki/Evolutionary_history_of_plants#Flowers


4/17

Flowers ofMalus sylvestris*crab apple-

:and plants have e$isted for about ,# million years.[/]arly land plants reproducedse$ually

with flagellated% swimming sperm% li&e the green algae from which they evolved. An

adaptation to terrestrialiation was the development of upright meiosporangia for dispersal by

sporesto new habitats. This feature is lac&ing in the descendants of their nearest algal

relatives% the ;harophyceangreen algae. A later terrestrial adaptation too& place withretention of the delicate% avascular se$ual stage% the gametophyte% within the tissues of the

vascular sporophyte. This occurred by spore germination within sporangia rather than spore

release% as in non!seed plants. A current e$ample of how this might have happened can be

seen in the precocious spore germination in Sellaginella% the spi&e!moss. The result for the

ancestors of angiosperms was enclosing them in a case% the seed. The first seed bearing plants%

li&e thegin&go% and conifers*such aspinesandfirs-% did not produce flowers. 'nterestingly%

the pollen grains *males- of "in&goand cycads produce a pair of flagellated% mobile sperm

cells that (swim( down the developing pollen tube to the female and her eggs.

The apparently sudden appearance of relatively modern flowers in the fossil record posed

such a problem for the theory ofevolutionthat it was called an (abominable mystery( by

;harles "arwin.[,]4owever% the fossil record has grown since the time of "arwin% and

recently discovered angiosperm fossils such asrchae'ructus% along with further discoveries

of fossil gymnosperms% suggest how angiosperm characteristics may have been acuired in a

series of steps. 6everal groups of e$tinct gymnosperms% particularly seed ferns% have been

proposed as theancestorsof flowering plants but there is no continuous fossil evidence

showing e$actly how flowers evolved. 6ome older fossils% such as the upper Triassic

Sanmiguelia% have been suggested. 2ased on current evidence% some propose that the

ancestors of the angiosperms diverged from an un&nown group of gymnosperms during the

late Triassic*#,9#0# million years ago-. A close relationship between angiosperms and

gnetophytes% proposed on the basis ofmorphologicalevidence% has more recently been
http://en.wikipedia.org/wiki/Malus_sylvestrishttp://en.wikipedia.org/wiki/Malus_sylvestrishttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-2http://en.wikipedia.org/wiki/Flowering_plant#cite_note-2http://en.wikipedia.org/wiki/Plant_sexualityhttp://en.wikipedia.org/wiki/Sporehttp://en.wikipedia.org/wiki/Charophyceaehttp://en.wikipedia.org/wiki/Seedhttp://en.wikipedia.org/wiki/Ginkgohttp://en.wikipedia.org/wiki/Ginkgohttp://en.wikipedia.org/wiki/Coniferhttp://en.wikipedia.org/wiki/Pinehttp://en.wikipedia.org/wiki/Pinehttp://en.wikipedia.org/wiki/Firhttp://en.wikipedia.org/wiki/Firhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Charles_Darwinhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-3http://en.wikipedia.org/wiki/Flowering_plant#cite_note-3http://en.wikipedia.org/wiki/Seed_fernhttp://en.wikipedia.org/wiki/Most_recent_common_ancestorhttp://en.wikipedia.org/wiki/Most_recent_common_ancestorhttp://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/w/index.php?title=Sanmiguelia&action=edit&redlink=1http://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/wiki/Gnetophytehttp://en.wikipedia.org/wiki/Morphology_(biology)http://en.wikipedia.org/wiki/Morphology_(biology)http://en.wikipedia.org/wiki/File:Malus_sylvestris_%28inflorescence%29.jpghttp://en.wikipedia.org/wiki/File:Malus_sylvestris_%28inflorescence%29.jpghttp://en.wikipedia.org/wiki/Malus_sylvestrishttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-2http://en.wikipedia.org/wiki/Plant_sexualityhttp://en.wikipedia.org/wiki/Sporehttp://en.wikipedia.org/wiki/Charophyceaehttp://en.wikipedia.org/wiki/Seedhttp://en.wikipedia.org/wiki/Ginkgohttp://en.wikipedia.org/wiki/Coniferhttp://en.wikipedia.org/wiki/Pinehttp://en.wikipedia.org/wiki/Firhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Charles_Darwinhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-3http://en.wikipedia.org/wiki/Seed_fernhttp://en.wikipedia.org/wiki/Most_recent_common_ancestorhttp://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/w/index.php?title=Sanmiguelia&action=edit&redlink=1http://en.wikipedia.org/wiki/Triassichttp://en.wikipedia.org/wiki/Gnetophytehttp://en.wikipedia.org/wiki/Morphology_(biology)


5/17

disputed on the basis of molecular evidencethat suggest gnetophytes are instead more closely

related to othergymnosperms.

The earliest &nown macrofossilconfidently identified as an angiosperm%rchae'ructus

liaoningensis% is dated to about 1# million years 2P *the ;retaceousperiod-%[]while pollen

considered to be of angiosperm origin ta&es thefossilrecord bac& to about 1/0 million years2P. 4owever% one study has suggested that the early!middle Burassicplant Schmeissneria%

traditionally considered a type ofgin&go% may be the earliest &nown angiosperm% or at least a

close relative.[+]Additionally% circumstantial chemical evidence has been found for the

e$istence of angiosperms as early as #0 million years ago. >leanane% a secondary metabolite

produced by many flowering plants% has been found inPermiandeposits of that age together

with fossils of gigantopterids.[)][C]5igantopterids are a group of e$tinct seed plants that share

many morphological traits with flowering plants% although they are not &nown to have been

flowering plants themselves.

7ecent "DAanalysis based on molecular systematics[E][10]showed thatmborella

trichopo(a% found on the Pacific island ofDew ;aledonia% belongs to asister groupof theother flowering plants% and morphological studies[11]suggest that it has features that may have

been characteristic of the earliest flowering plants.

The great angiospermradiation% when a great diversity of angiosperms appears in the fossil

record% occurred in the mid!;retaceous*appro$imately 100 million years ago-. 4owever% a

study in #00) estimated that the division of the five most recent *the genus Ceratophyllum%

the family ;hloranthaceae% the eudicots% the magnoliids% and the monocots- of the eight main

groups occurred around 1,0 million years ago.[1#]2y the late ;retaceous% angiosperms appear

to have dominated environments formerly occupied by fernsandcycadophytes% but large

canopy!forming trees replacedconifersas the dominant trees only close to the end of the

;retaceous+ millions years ago or even later% at the beginning of the Tertiary.[1/]The

radiation of herbaceous angiosperm occurred much later.[1,]8et% many fossil plants

recogniable as belonging to modern families *includingbeech% oa&%maple% and magnolia-

appeared already at late;retaceous.

Twobeeson a flower head of ;reeping Thistle% Cirsium arvense

't is generally assumed that the functionof flowers% from the start% was to involve mobileanimalsin theirreproductionprocesses. That is% pollen can be scattered even if the flower is
http://en.wikipedia.org/wiki/Molecular_biologyhttp://en.wikipedia.org/wiki/Gymnospermhttp://en.wikipedia.org/wiki/Gymnospermhttp://en.wikipedia.org/wiki/Macrofossilhttp://en.wikipedia.org/wiki/Archaefructushttp://en.wikipedia.org/wiki/Archaefructushttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-4http://en.wikipedia.org/wiki/Flowering_plant#cite_note-4http://en.wikipedia.org/wiki/Fossilhttp://en.wikipedia.org/wiki/Fossilhttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Schmeissneriahttp://en.wikipedia.org/wiki/Ginkgohttp://en.wikipedia.org/wiki/Ginkgohttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-5http://en.wikipedia.org/wiki/Oleananehttp://en.wikipedia.org/wiki/Secondary_metabolitehttp://en.wikipedia.org/wiki/Permianhttp://en.wikipedia.org/wiki/Permianhttp://en.wikipedia.org/wiki/Gigantopteridhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-6http://en.wikipedia.org/wiki/Flowering_plant#cite_note-6http://en.wikipedia.org/wiki/Flowering_plant#cite_note-7http://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/Molecular_systematicshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-8http://en.wikipedia.org/wiki/Flowering_plant#cite_note-8http://en.wikipedia.org/wiki/Flowering_plant#cite_note-9http://en.wikipedia.org/wiki/Amborellahttp://en.wikipedia.org/wiki/Amborellahttp://en.wikipedia.org/wiki/New_Caledoniahttp://en.wikipedia.org/wiki/Sister_grouphttp://en.wikipedia.org/wiki/Sister_grouphttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-10http://en.wikipedia.org/wiki/Flowering_plant#cite_note-10http://en.wikipedia.org/wiki/Adaptive_radiationhttp://en.wikipedia.org/wiki/Adaptive_radiationhttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Ceratophyllumhttp://en.wikipedia.org/wiki/Chloranthaceaehttp://en.wikipedia.org/wiki/Eudicothttp://en.wikipedia.org/wiki/Magnoliidhttp://en.wikipedia.org/wiki/Monocothttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-11http://en.wikipedia.org/wiki/Fernhttp://en.wikipedia.org/wiki/Cycadophytehttp://en.wikipedia.org/wiki/Cycadophytehttp://en.wikipedia.org/wiki/Coniferhttp://en.wikipedia.org/wiki/Coniferhttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Tertiaryhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-SadavaHeller2006-12http://en.wikipedia.org/wiki/Flowering_plant#cite_note-SadavaHeller2006-12http://en.wikipedia.org/wiki/Flowering_plant#cite_note-13http://en.wikipedia.org/wiki/Beechhttp://en.wikipedia.org/wiki/Oakhttp://en.wikipedia.org/wiki/Maplehttp://en.wikipedia.org/wiki/Maplehttp://en.wikipedia.org/wiki/Magnoliahttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Beehttp://en.wikipedia.org/wiki/Beehttp://en.wikipedia.org/wiki/Cirsium_arvensehttp://en.wikipedia.org/wiki/Function_(biology)http://en.wikipedia.org/wiki/Animalhttp://en.wikipedia.org/wiki/Animalhttp://en.wikipedia.org/wiki/Reproductionhttp://en.wikipedia.org/wiki/Reproductionhttp://en.wikipedia.org/wiki/File:Cirsium_arvense_with_Bees_Richard_Bartz.jpghttp://en.wikipedia.org/wiki/File:Cirsium_arvense_with_Bees_Richard_Bartz.jpghttp://en.wikipedia.org/wiki/Molecular_biologyhttp://en.wikipedia.org/wiki/Gymnospermhttp://en.wikipedia.org/wiki/Macrofossilhttp://en.wikipedia.org/wiki/Archaefructushttp://en.wikipedia.org/wiki/Archaefructushttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-4http://en.wikipedia.org/wiki/Fossilhttp://en.wikipedia.org/wiki/Jurassichttp://en.wikipedia.org/wiki/Schmeissneriahttp://en.wikipedia.org/wiki/Ginkgohttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-5http://en.wikipedia.org/wiki/Oleananehttp://en.wikipedia.org/wiki/Secondary_metabolitehttp://en.wikipedia.org/wiki/Permianhttp://en.wikipedia.org/wiki/Gigantopteridhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-6http://en.wikipedia.org/wiki/Flowering_plant#cite_note-7http://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/Molecular_systematicshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-8http://en.wikipedia.org/wiki/Flowering_plant#cite_note-9http://en.wikipedia.org/wiki/Amborellahttp://en.wikipedia.org/wiki/Amborellahttp://en.wikipedia.org/wiki/New_Caledoniahttp://en.wikipedia.org/wiki/Sister_grouphttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-10http://en.wikipedia.org/wiki/Adaptive_radiationhttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Ceratophyllumhttp://en.wikipedia.org/wiki/Chloranthaceaehttp://en.wikipedia.org/wiki/Eudicothttp://en.wikipedia.org/wiki/Magnoliidhttp://en.wikipedia.org/wiki/Monocothttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-11http://en.wikipedia.org/wiki/Fernhttp://en.wikipedia.org/wiki/Cycadophytehttp://en.wikipedia.org/wiki/Coniferhttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Tertiaryhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-SadavaHeller2006-12http://en.wikipedia.org/wiki/Flowering_plant#cite_note-13http://en.wikipedia.org/wiki/Beechhttp://en.wikipedia.org/wiki/Oakhttp://en.wikipedia.org/wiki/Maplehttp://en.wikipedia.org/wiki/Magnoliahttp://en.wikipedia.org/wiki/Cretaceoushttp://en.wikipedia.org/wiki/Beehttp://en.wikipedia.org/wiki/Cirsium_arvensehttp://en.wikipedia.org/wiki/Function_(biology)http://en.wikipedia.org/wiki/Animalhttp://en.wikipedia.org/wiki/Reproduction


6/17

not brightly coloredor oddly shaped in a way that attracts animals= however% by e$pending

the energy reuired to create such traits% angiosperms can enlist the aid of animals and thus

reproduce more efficiently.

'sland geneticsprovides one proposed e$planation for the sudden% fully developed appearance

of flowering plants. 'sland genetics is believed to be a common source of speciationingeneral% especially when it comes to radical adaptations that seem to have reuired inferior

transitional forms. Flowering plants may have evolved in an isolated setting li&e an islandor

island chain% where the plants bearing them were able to develop a highly specialied

relationship with some specific animal *a wasp% for e$ample-. 6uch a relationship% with a

hypothetical wasp carrying pollen from one plant to another much the way fig waspsdo

today% could result in both the plant*s- and their partners developing a high degree of

specialiation. Dote that the wasp e$ample is not incidental=bees% which apparently evolved

specifically due to mutualistic plant relationships% are descended from wasps.

Animals are also involved in the distribution of seeds. Fruit% which is formed by the

enlargement of flower parts% is freuently a seed!dispersal tool that attracts animals to eat orotherwise disturb it% incidentally scattering the seeds it contains *see frugivory-. hile many

such mutualistic relationshipsremain too fragile to survive competitionand to spread widely%

flowering proved to be an unusually effective means of reproduction% spreading *whatever its

origin- to become the dominant form of land plant life.

Flower ontogenyuses a combination ofgenesnormally responsible for forming new shoots.[1]The most primitive flowers are thought to have had a variable number of flower parts%

often separate from *but in contact with- each other. The flowers would have tended to grow

in a spiral pattern% to be bise$ual *in plants% this means both male and female parts on the

same flower-% and to be dominated by the ovary*female part-. As flowers grew more

advanced% some variations developed parts fused together% with a much more specific number

and design% and with either specific se$es per flower or plant% or at least (ovary inferior(.

Flower evolution continues to the present day= modern flowers have been so profoundly

influenced by humans that some of them cannot be pollinated in nature. any modern%

domesticated flowers used to be simple weeds% which only sprouted when the ground was

disturbed. 6ome of them tended to grow with human crops% perhaps already having symbiotic

companion plantrelationships with them% and the prettiest did not get pluc&ed because of their

beauty% developing a dependence upon and special adaptation to human affection.

Classification

There are eight groups of living angiosperms3

mborella< a single species of shrub fromDew ;aledonia

Dymphaeales< about C0 species[1E]< water liliesand4ydatellaceae

Austrobaileyales< about 100 species[1E]of woody plantsfrom various parts of the

world

;hloranthales< several doen species of aromatic plants with toothed leaves
http://en.wikipedia.org/wiki/Colorhttp://en.wikipedia.org/wiki/Colorhttp://en.wikipedia.org/wiki/Island_geneticshttp://en.wikipedia.org/wiki/Speciationhttp://en.wikipedia.org/wiki/Islandhttp://en.wikipedia.org/wiki/Wasphttp://en.wikipedia.org/wiki/Fig_wasphttp://en.wikipedia.org/wiki/Specialization_(biology)http://en.wikipedia.org/wiki/Beeshttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Frugivoryhttp://en.wikipedia.org/wiki/Mutualism_(biology)http://en.wikipedia.org/wiki/Competition_(biology)http://en.wikipedia.org/wiki/Ontogenyhttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-14http://en.wikipedia.org/wiki/Ovary_(plants)http://en.wikipedia.org/wiki/Companion_planthttp://en.wikipedia.org/wiki/Companion_planthttp://en.wikipedia.org/wiki/Amborellahttp://en.wikipedia.org/wiki/New_Caledoniahttp://en.wikipedia.org/wiki/Nymphaealeshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Nymphaeaceaehttp://en.wikipedia.org/wiki/Hydatellaceaehttp://en.wikipedia.org/wiki/Hydatellaceaehttp://en.wikipedia.org/wiki/Austrobaileyaleshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Woody_planthttp://en.wikipedia.org/wiki/Chloranthaleshttp://en.wikipedia.org/wiki/Colorhttp://en.wikipedia.org/wiki/Island_geneticshttp://en.wikipedia.org/wiki/Speciationhttp://en.wikipedia.org/wiki/Islandhttp://en.wikipedia.org/wiki/Wasphttp://en.wikipedia.org/wiki/Fig_wasphttp://en.wikipedia.org/wiki/Specialization_(biology)http://en.wikipedia.org/wiki/Beeshttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Frugivoryhttp://en.wikipedia.org/wiki/Mutualism_(biology)http://en.wikipedia.org/wiki/Competition_(biology)http://en.wikipedia.org/wiki/Ontogenyhttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-14http://en.wikipedia.org/wiki/Ovary_(plants)http://en.wikipedia.org/wiki/Companion_planthttp://en.wikipedia.org/wiki/Amborellahttp://en.wikipedia.org/wiki/New_Caledoniahttp://en.wikipedia.org/wiki/Nymphaealeshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Nymphaeaceaehttp://en.wikipedia.org/wiki/Hydatellaceaehttp://en.wikipedia.org/wiki/Austrobaileyaleshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Woody_planthttp://en.wikipedia.org/wiki/Chloranthales


7/17

agnoliidae< about E%000 species%[1E]characteried bytrimerousflowers% pollen

with one pore% and usually branching!veined leaves < for e$ample magnolias%bay

laurel%andblac& pepper

onocotyledonae < about )0%000 species%[1E]characteried by trimerous flowers% a

singlecotyledon% pollen with one pore% and usually parallel!veined leaves < fore$amplegrasses% orchids% andpalms

Ceratophyllum< about + species[1E]of auatic plants% perhaps most familiar as

auariumplants

udicotyledonae< about 1)%000 species%[1E]characteried by ,! or ! merous

flowers% pollen with three pores% and usually branching!veined leaves < for e$ample

sunflowers%petunia%buttercup% applesand oa&s

The e$act relationship between these eight groups is not yet clear% although there is agreement

that the first three groups to diverge from the ancestral angiosperm were Amborellales%

Dymphaeales%andAustrobaileyales.[#0]The termbasal angiospermsrefers to these three

groups. The five other groups form the clade esangiospermae. The relationship between the

three largest of these groups *magnoliids% monocots and eudicots- remains unclear. 6ome

analyses ma&e the magnoliids the first to diverge% others the monocots. [1C]. Ceratophyllum

seems to group with theeudicotsrather than with the monocots.

ascular anatomy

The amount and comple$ityof tissue!formation in flowering plants e$ceeds that of

gymnosperms. The vascular bundlesof the stem are arranged such that the $ylemandphloem

form concentric rings.

'n the dicotyledons% the bundles in the very young stem are arranged in an open ring%

separating a central pith from an outer corte$. 'n each bundle% separating the $ylem and

phloem% is a layer of meristemor active formative tissue &nown as cambium. 2y the

formation of a layer of cambium between the bundles *interfascicular cambium- a complete

ring is formed% and a regular periodical increase in thic&ness results from the development of

$ylem on the inside and phloem on the outside. The soft phloem becomes crushed% but the

hard wood persists and forms the bul& of the stem and branches of the woody perennial.

>wing to differences in the character of the elements produced at the beginning and end of

the season% the wood is mar&ed out in transverse section into concentric rings% one for each

seasonof growth% calledannual rings.

Among the monocotyledons% the bundles are more numerous in the young stem and are

scattered through the ground tissue. They contain no cambium and once formed the stem

increases in diameter only in e$ceptional cases.

!he flower" fruit" and seed

The characteristic feature of angiosperms is the flower. Flowers show remar&able variation in

form and elaboration% and provide the most trustworthy e$ternal characteristics for

establishing relationships among angiosperm species. The function of the flower is to ensurefertiliation of the ovule and development offruitcontaining seeds. The floral apparatus may
http://en.wikipedia.org/wiki/Magnoliidaehttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Merosityhttp://en.wikipedia.org/wiki/Merosityhttp://en.wikipedia.org/wiki/Magnoliahttp://en.wikipedia.org/wiki/Bay_laurelhttp://en.wikipedia.org/wiki/Bay_laurelhttp://en.wikipedia.org/wiki/Bay_laurelhttp://en.wikipedia.org/wiki/Black_pepperhttp://en.wikipedia.org/wiki/Black_pepperhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Cotyledonhttp://en.wikipedia.org/wiki/Cotyledonhttp://en.wikipedia.org/wiki/Poaceaehttp://en.wikipedia.org/wiki/Poaceaehttp://en.wikipedia.org/wiki/Orchidhttp://en.wikipedia.org/wiki/Arecaceaehttp://en.wikipedia.org/wiki/Ceratophyllumhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Aquatic_planthttp://en.wikipedia.org/wiki/Aquariumhttp://en.wikipedia.org/wiki/Aquariumhttp://en.wikipedia.org/wiki/Eudicotshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Merosityhttp://en.wikipedia.org/wiki/Sunflowerhttp://en.wikipedia.org/wiki/Petuniahttp://en.wikipedia.org/wiki/Petuniahttp://en.wikipedia.org/wiki/Buttercuphttp://en.wikipedia.org/wiki/Applehttp://en.wikipedia.org/wiki/Oakhttp://en.wikipedia.org/wiki/Amborellaleshttp://en.wikipedia.org/wiki/Nymphaealeshttp://en.wikipedia.org/wiki/Nymphaealeshttp://en.wikipedia.org/wiki/Austrobaileyaleshttp://en.wikipedia.org/wiki/Austrobaileyaleshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-19http://en.wikipedia.org/wiki/Basal_angiospermhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-Bell_et_all_2010-17http://en.wikipedia.org/wiki/Ceratophyllumhttp://en.wikipedia.org/wiki/Eudicotshttp://en.wikipedia.org/wiki/Eudicotshttp://en.wikipedia.org/wiki/Monocotshttp://en.wikipedia.org/wiki/Complexityhttp://en.wikipedia.org/wiki/Vascular_bundlehttp://en.wikipedia.org/wiki/Vascular_bundlehttp://en.wikipedia.org/wiki/Xylemhttp://en.wikipedia.org/wiki/Phloemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Cambium_(disambiguation)http://en.wikipedia.org/wiki/Seasonhttp://en.wikipedia.org/wiki/Annual_ringshttp://en.wikipedia.org/wiki/Annual_ringshttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Seedhttp://en.wikipedia.org/wiki/Magnoliidaehttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Merosityhttp://en.wikipedia.org/wiki/Magnoliahttp://en.wikipedia.org/wiki/Bay_laurelhttp://en.wikipedia.org/wiki/Bay_laurelhttp://en.wikipedia.org/wiki/Black_pepperhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Cotyledonhttp://en.wikipedia.org/wiki/Poaceaehttp://en.wikipedia.org/wiki/Orchidhttp://en.wikipedia.org/wiki/Arecaceaehttp://en.wikipedia.org/wiki/Ceratophyllumhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Aquatic_planthttp://en.wikipedia.org/wiki/Aquariumhttp://en.wikipedia.org/wiki/Eudicotshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-palmer-18http://en.wikipedia.org/wiki/Merosityhttp://en.wikipedia.org/wiki/Sunflowerhttp://en.wikipedia.org/wiki/Petuniahttp://en.wikipedia.org/wiki/Buttercuphttp://en.wikipedia.org/wiki/Applehttp://en.wikipedia.org/wiki/Oakhttp://en.wikipedia.org/wiki/Amborellaleshttp://en.wikipedia.org/wiki/Nymphaealeshttp://en.wikipedia.org/wiki/Austrobaileyaleshttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-19http://en.wikipedia.org/wiki/Basal_angiospermhttp://en.wikipedia.org/wiki/Flowering_plant#cite_note-Bell_et_all_2010-17http://en.wikipedia.org/wiki/Ceratophyllumhttp://en.wikipedia.org/wiki/Eudicotshttp://en.wikipedia.org/wiki/Monocotshttp://en.wikipedia.org/wiki/Complexityhttp://en.wikipedia.org/wiki/Vascular_bundlehttp://en.wikipedia.org/wiki/Xylemhttp://en.wikipedia.org/wiki/Phloemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Cambium_(disambiguation)http://en.wikipedia.org/wiki/Seasonhttp://en.wikipedia.org/wiki/Annual_ringshttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Seed


8/17

arise terminally on a shoot or from the a$il of a leaf *where the petioleattaches to the stem-.

>ccasionally% as in violets% a flower arises singly in the a$il of an ordinary foliage!leaf. ore

typically% the flower!bearing portion of the plant is sharply distinguished from the foliage!

bearing or vegetative portion% and forms a more or less elaborate branch!system called an

inflorescence.

The reproductive cells produced by flowers are of two &inds. icrospores% which will divide

to becomepollen grains% are the (male( cells and are borne in thestamens*or

microsporophylls-. The (female( cells called megaspores% which will divide to become the

egg!cell *megagametogenesis-% are contained in the ovuleand enclosed in the carpel*or

megasporophyll-.

The flower may consist only of these parts% as inwillow% where each flower comprises only a

few stamens or two carpels. Gsually other structures are present and serve to protect the

sporophylls and to form an envelope attractive to pollinators. The individual members of

these surrounding structures are &nown assepalsandpetals*or tepalsin flowers such as

Magnoliawhere sepals and petals are not distinguishable from each other-. The outer series*caly$ of sepals- is usually green and leaf!li&e% and functions to protect the rest of the flower%

especially the bud. The inner series *corolla of petals- is generally white or brightly colored%

and is more delicate in structure. 't functions to attract insectorbirdpollinators. Attraction is

effected by color% scent% and nectar% which may be secreted in some part of the flower. The

characteristics that attract pollinators account for the popularity of flowers and flowering

plants among humans.

hile the ma?ority of flowers are perfect orhermaphrodite*having both male and female

parts in the same flower structure-% flowering plants have developed numerous morphological

andphysiologicalmechanisms to reduce or prevent self!fertiliation. 4eteromorphic flowers

have short carpels and long stamens% or vice versa% so animalpollinatorscannot easily transfer

pollen to the pistil *receptive part of the carpel-. 4omomorphic flowers may employ a

biochemical *physiological- mechanism called self!incompatibilityto discriminate between

self! and non!self pollen grains. 'n other species% the male and female parts are

morphologically separated% developing on different flowers.

Fertilization and embryogenesis

"ouble fertiliationrefers to a process in which two spermcells fertilie cellsin the ovary.

This process begins when apollengrain adheres to the stigma of thepistil*female

reproductive structure-% germinates% and grows a longpollen tube. hile this pollen tube isgrowing% a haploid generative cell travels down the tube behind the tube nucleus. The

generative cell divides by mitosis to produce two haploid *n- sperm cells. As the pollen tube

grows% it ma&es its way from the stigma% down the style and into the ovary. 4ere the pollen

tube reaches the micropyle of the ovule and digests its way into one of the synergids%

releasing its contents *which include the sperm cells-. The synergid that the cells were

released into degenerates and one sperm ma&es its way to fertilie the egg cell% producing a

diploid *#n- ygote. The second sperm cell fuses with both central cell nuclei% producing a

triploid */n- cell. As the ygote develops into an embryo% the triploid cell develops into the

endosperm% which serves as the embryoHs food supply. The ovary now will develop into fruit

and the ovule will develop into seed.
http://en.wikipedia.org/wiki/Petiole_(botany)http://en.wikipedia.org/wiki/Violet_(plant)http://en.wikipedia.org/wiki/Inflorescencehttp://en.wikipedia.org/wiki/Pollenhttp://en.wikipedia.org/wiki/Pollenhttp://en.wikipedia.org/wiki/Stamenhttp://en.wikipedia.org/wiki/Stamenhttp://en.wikipedia.org/wiki/Megagametogenesishttp://en.wikipedia.org/wiki/Ovulehttp://en.wikipedia.org/wiki/Carpelhttp://en.wikipedia.org/wiki/Willowhttp://en.wikipedia.org/wiki/Willowhttp://en.wikipedia.org/wiki/Sepalhttp://en.wikipedia.org/wiki/Sepalhttp://en.wikipedia.org/wiki/Petalhttp://en.wikipedia.org/wiki/Tepalhttp://en.wikipedia.org/wiki/Magnoliahttp://en.wikipedia.org/wiki/Insecthttp://en.wikipedia.org/wiki/Birdhttp://en.wikipedia.org/wiki/Scenthttp://en.wikipedia.org/wiki/Nectarhttp://en.wikipedia.org/wiki/Hermaphroditehttp://en.wikipedia.org/wiki/Hermaphroditehttp://en.wikipedia.org/wiki/Physiologicalhttp://en.wikipedia.org/wiki/Pollinatorhttp://en.wikipedia.org/wiki/Self-incompatibility_in_plantshttp://en.wikipedia.org/wiki/Double_fertilizationhttp://en.wikipedia.org/wiki/Double_fertilizationhttp://en.wikipedia.org/wiki/Spermhttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Plant_ovaryhttp://en.wikipedia.org/wiki/Pollenhttp://en.wikipedia.org/wiki/Pistilhttp://en.wikipedia.org/wiki/Pollen_tubehttp://en.wikipedia.org/wiki/Pollen_tubehttp://en.wikipedia.org/wiki/Petiole_(botany)http://en.wikipedia.org/wiki/Violet_(plant)http://en.wikipedia.org/wiki/Inflorescencehttp://en.wikipedia.org/wiki/Pollenhttp://en.wikipedia.org/wiki/Stamenhttp://en.wikipedia.org/wiki/Megagametogenesishttp://en.wikipedia.org/wiki/Ovulehttp://en.wikipedia.org/wiki/Carpelhttp://en.wikipedia.org/wiki/Willowhttp://en.wikipedia.org/wiki/Sepalhttp://en.wikipedia.org/wiki/Petalhttp://en.wikipedia.org/wiki/Tepalhttp://en.wikipedia.org/wiki/Magnoliahttp://en.wikipedia.org/wiki/Insecthttp://en.wikipedia.org/wiki/Birdhttp://en.wikipedia.org/wiki/Scenthttp://en.wikipedia.org/wiki/Nectarhttp://en.wikipedia.org/wiki/Hermaphroditehttp://en.wikipedia.org/wiki/Physiologicalhttp://en.wikipedia.org/wiki/Pollinatorhttp://en.wikipedia.org/wiki/Self-incompatibility_in_plantshttp://en.wikipedia.org/wiki/Double_fertilizationhttp://en.wikipedia.org/wiki/Spermhttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Plant_ovaryhttp://en.wikipedia.org/wiki/Pollenhttp://en.wikipedia.org/wiki/Pistilhttp://en.wikipedia.org/wiki/Pollen_tube


9/17

Fruit and seed

As the development of embryo and endosperm proceeds within the embryo!sac% the sac wall

enlarges and combines with the nucellus*which is li&ewise enlarging- and the integumentto

form thesee()coat. The ovary wall develops to form thefruitorpericarp% whose form is

closely associated with the manner of distribution of the seed.

Freuently the influence of fertiliation is felt beyond the ovary% and other parts of the flowerta&e part in the formation of the fruit% e*g*the floral receptacle in the apple% strawberryand

others.

The character of the seed!coat bears a definite relation to that of the fruit. They protect the

embryo and aid in dissemination= they may also directly promote germination. Among plants

with indehiscent fruits% the fruit generally provides protection for the embryo and secures

dissemination. 'n this case% the seed!coat is only slightly developed. 'f the fruit is dehiscent

and the seed is e$posed% the seed!coat is generally well developed% and must discharge the

functions otherwise e$ecuted by the fruit.
http://en.wikipedia.org/wiki/Nucellushttp://en.wikipedia.org/wiki/Nucellushttp://en.wikipedia.org/wiki/Integumenthttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Pericarphttp://en.wikipedia.org/wiki/Ovaryhttp://en.wikipedia.org/wiki/Applehttp://en.wikipedia.org/wiki/Strawberryhttp://en.wikipedia.org/wiki/Dehiscence_(botany)http://en.wikipedia.org/wiki/Nucellushttp://en.wikipedia.org/wiki/Integumenthttp://en.wikipedia.org/wiki/Fruithttp://en.wikipedia.org/wiki/Pericarphttp://en.wikipedia.org/wiki/Ovaryhttp://en.wikipedia.org/wiki/Applehttp://en.wikipedia.org/wiki/Strawberryhttp://en.wikipedia.org/wiki/Dehiscence_(botany)


10/17

Economic importance

Agricultureis almost entirely dependent on angiosperms% either directly or indirectly through

livestoc&feed. >f all the families plants% the Poaceae% or grass family% is by far the most

important% providing the bul& of all feedstoc&s *rice% corn < maie% wheat%barley%rye% oats%

pearl millet% sugar cane% sorghum-. TheFabaceae% or legume family% comes in second place.

Also of high importance are the 6olanaceae% or nightshade family *potatoes%tomatoes% and

peppers%among others-% the ;ucurbitaceae% or gourdfamily *also includingpump&insand

melons-% the 2rassicaceae% or mustard plantfamily *including rapeseedand the innumerable

varieties of the cabbagespecies$rassica oleracea-% and the Apiaceae% orparsleyfamily.

any of our fruits come from the 7utaceae% or rue family% and the 7osaceae% or rose family

*including apples%pears%cherries%apricots%plums% etc.-.

'n some parts of the world% certain single species assume paramount importance because of

their variety of uses% for e$ample the coconut *Cocos nuci'era- on Pacific atolls% and the olive

*Olea europaea- in theediterranean region.

Flowering plants also provide economic resources in the form of wood%paper% fiber *cotton%

fla$% and hemp% among others-% medicines *digitalis% camphor-% decorative and landscaping

plants% and many other uses. The main area in which they are surpassed by other plants is

timberproduction.

#ntroduction to e$amples of angiosperms

The angiosperms are flowering plants and biggest group in plant &ingdom with at least

#+0%000 living species grouped under ,/ families. They bear true roots% leaves% stems%

flowers% and seed. The seeds are formed in the ovary present within a flower. Angiosperms

flower contains the male andIor female parts of the plant. Angiosperm seeds are covered withfruit% which is a characteristic feature of these plants.

E$amples of Angiosperms % &ased on the 'umber of

Cotyledons (resent

Monocots or monocotyledons) onocot seedlings contain only one cotyledon.

E$amples of Monocots%rice% wheat% maie% orchids% sugar cane% bamboos% Arecaceae spp%

usaceae spp% Jingiberaceae spp% lilies% daffodils% irises% amaryllis% orchids% ;aladium%

6pathiphyllum% Philodendron% Anthurium% cannas% bluebells% tulips% etc
http://en.wikipedia.org/wiki/Agriculturehttp://en.wikipedia.org/wiki/Agriculturehttp://en.wikipedia.org/wiki/Livestockhttp://en.wikipedia.org/wiki/Livestockhttp://en.wikipedia.org/wiki/Poaceaehttp://en.wikipedia.org/wiki/Ricehttp://en.wikipedia.org/wiki/Maizehttp://en.wikipedia.org/wiki/Wheathttp://en.wikipedia.org/wiki/Barleyhttp://en.wikipedia.org/wiki/Barleyhttp://en.wikipedia.org/wiki/Ryehttp://en.wikipedia.org/wiki/Ryehttp://en.wikipedia.org/wiki/Oathttp://en.wikipedia.org/wiki/Pearl_millethttp://en.wikipedia.org/wiki/Sugar_canehttp://en.wikipedia.org/wiki/Sorghumhttp://en.wikipedia.org/wiki/Fabaceaehttp://en.wikipedia.org/wiki/Fabaceaehttp://en.wikipedia.org/wiki/Solanaceaehttp://en.wikipedia.org/wiki/Potatohttp://en.wikipedia.org/wiki/Tomatohttp://en.wikipedia.org/wiki/Tomatohttp://en.wikipedia.org/wiki/Capsicumhttp://en.wikipedia.org/wiki/Capsicumhttp://en.wikipedia.org/wiki/Cucurbitaceaehttp://en.wikipedia.org/wiki/Gourdhttp://en.wikipedia.org/wiki/Pumpkinhttp://en.wikipedia.org/wiki/Melonhttp://en.wikipedia.org/wiki/Brassicaceaehttp://en.wikipedia.org/wiki/Mustard_planthttp://en.wikipedia.org/wiki/Rapeseedhttp://en.wikipedia.org/wiki/Cabbagehttp://en.wikipedia.org/wiki/Brassica_oleraceahttp://en.wikipedia.org/wiki/Apiaceaehttp://en.wikipedia.org/wiki/Parsleyhttp://en.wikipedia.org/wiki/Rutaceaehttp://en.wikipedia.org/wiki/Rosaceaehttp://en.wikipedia.org/wiki/Applehttp://en.wikipedia.org/wiki/Pearhttp://en.wikipedia.org/wiki/Pearhttp://en.wikipedia.org/wiki/Cherryhttp://en.wikipedia.org/wiki/Cherryhttp://en.wikipedia.org/wiki/Apricotshttp://en.wikipedia.org/wiki/Apricotshttp://en.wikipedia.org/wiki/Plumshttp://en.wikipedia.org/wiki/Coconuthttp://en.wikipedia.org/wiki/Atollhttp://en.wikipedia.org/wiki/Olivehttp://en.wikipedia.org/wiki/Mediterranean_regionhttp://en.wikipedia.org/wiki/Mediterranean_regionhttp://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Paperhttp://en.wikipedia.org/wiki/Cottonhttp://en.wikipedia.org/wiki/Flaxhttp://en.wikipedia.org/wiki/Hemphttp://en.wikipedia.org/wiki/Digitalishttp://en.wikipedia.org/wiki/Camphorhttp://en.wikipedia.org/wiki/Timberhttp://en.wikipedia.org/wiki/Timberhttp://en.wikipedia.org/wiki/Agriculturehttp://en.wikipedia.org/wiki/Livestockhttp://en.wikipedia.org/wiki/Poaceaehttp://en.wikipedia.org/wiki/Ricehttp://en.wikipedia.org/wiki/Maizehttp://en.wikipedia.org/wiki/Wheathttp://en.wikipedia.org/wiki/Barleyhttp://en.wikipedia.org/wiki/Ryehttp://en.wikipedia.org/wiki/Oathttp://en.wikipedia.org/wiki/Pearl_millethttp://en.wikipedia.org/wiki/Sugar_canehttp://en.wikipedia.org/wiki/Sorghumhttp://en.wikipedia.org/wiki/Fabaceaehttp://en.wikipedia.org/wiki/Solanaceaehttp://en.wikipedia.org/wiki/Potatohttp://en.wikipedia.org/wiki/Tomatohttp://en.wikipedia.org/wiki/Capsicumhttp://en.wikipedia.org/wiki/Cucurbitaceaehttp://en.wikipedia.org/wiki/Gourdhttp://en.wikipedia.org/wiki/Pumpkinhttp://en.wikipedia.org/wiki/Melonhttp://en.wikipedia.org/wiki/Brassicaceaehttp://en.wikipedia.org/wiki/Mustard_planthttp://en.wikipedia.org/wiki/Rapeseedhttp://en.wikipedia.org/wiki/Cabbagehttp://en.wikipedia.org/wiki/Brassica_oleraceahttp://en.wikipedia.org/wiki/Apiaceaehttp://en.wikipedia.org/wiki/Parsleyhttp://en.wikipedia.org/wiki/Rutaceaehttp://en.wikipedia.org/wiki/Rosaceaehttp://en.wikipedia.org/wiki/Applehttp://en.wikipedia.org/wiki/Pearhttp://en.wikipedia.org/wiki/Cherryhttp://en.wikipedia.org/wiki/Apricotshttp://en.wikipedia.org/wiki/Plumshttp://en.wikipedia.org/wiki/Coconuthttp://en.wikipedia.org/wiki/Atollhttp://en.wikipedia.org/wiki/Olivehttp://en.wikipedia.org/wiki/Mediterranean_regionhttp://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Paperhttp://en.wikipedia.org/wiki/Cottonhttp://en.wikipedia.org/wiki/Flaxhttp://en.wikipedia.org/wiki/Hemphttp://en.wikipedia.org/wiki/Digitalishttp://en.wikipedia.org/wiki/Camphorhttp://en.wikipedia.org/wiki/Timber


11/17

Dicots or dicotcotyledons)"icot seedlings contains two cotyledons

E$amples of dicots%ater!lilies% groundnuts% sunflower% apple% cabbage% brin?al% mango%

grapes% 4ornworts% 2uttercups K crowfoots% Poppies% Fumitories% lms% 4ops% Dettles% 2og!

myrtles% 2eeches K oa&s% 2irches% "ew!plants% 5oosefoots K oraches% Purslanes% ;ampions%

Lnotweeds% Thrifts% aterworts% allows% Pitcherplants% 6undews% Miolets K pansies% hitebryonies% Poplars K willows% ;rucifers% ignonettes% ;rowberries% 4eathers% intergreens%

etc

E$amples of Angiosperms % &ased on the (hysical 'ature

of the (lant*

1. 4erbs! Plants without stems above the ground. .g. banana% grasses% maie% etc

#. 6hrubs! A woody plant generally with multiple stems. .g. rose% hibiscus%

/. Trees! A perennial plant with single large stem. .g. mango% neem% palm% etc

E$amples of Angiosperms % &ased on the Duration of Life

+pan

1. Annuals% these plants complete their entire life cycle in one year. .g. 6unflower% Pea%

ustard% 2ean% 7ice% aie% etc.

#. &iennials%plants that complete their entire life cycle in two years. .g. ;arrot%

2eetroot% 7adish% Turnip% etc.

/. (erennials%plants that live for several years. .g.% ango% "ahlia% 7ose% 2amboo% etc.


12/17

Angiosperms represent the most advanced group of vascular plants. They are commonly

called HFlowering plantsH. They e$ceed all other ma?or groups of living plants in number and

diversity.

Angiosperms grow in almost every &ind of habitat. They occur in very high altitudes% even inAntarctica% in deserts% in shallow waters and even on other plants as parasites.

The adult plant body of an Angiosperm is a sporophyte with a well defined root% stemand

leaves. The root may be a taproot or fibrous root. The stem may soft and green *herbaceous-

or hard and woody. The leaves may be simple or compound.

The most important feature in angiosperms is that they e$hibit reproductive structures called

flowers. The flowers contain certain structures arranged in four whorls. The outer whorls

contain accessory structures such as sepalsand petalsand the two inner whorls containing

essential structures such as stamensand carpels.

The stamensrepresent microsporophylls. ach stamen has an anther and a filament. The

anther produces pollen grains containing the highly reduced male gametophyte. The carpels

represent megasporophyll. They enclose ovules containing the egg cell which with the

associated cells represent the female gametophyte.

A characteristic feature of angiosperms is the occurrence of a phenomenon called double

fertilisationone male gamete fuses with the egg cell to form a ygote while another male

gamete fuses with a dipolid secondary nucleus% to form a triploid endosperm *triple fusion-.

Following pollination and fertiliation% the ovule transforms into the seed while the ovary that

encloses the ovule% transforms into the fruit. Thus% seeds are enclosed in fruits.


13/17

Life Cycle of an Angiosperm

Life +tyles in Angiosperms

Angiosperms e$hibit a great diversity in form% sie% structure and life span of the plant body.

2ased on the duration of life span% angiosperms are classified into annuals% biennials and

perennials.

Annuals

are plants which complete their life cycle in one season.

.g.% 6unflower% ustard% Pea% 2ean% 7ice% aie.

&iennials

are plants that complete their life cycle in two years. 'n the second year of their life

span they produce flowers% fruits and seeds.

.g.% ;arrot% 7adish% 2eetroot% Turnip.

(erennials


14/17

are plants that live for more than two years. very year they produce flowers% fruits

and seeds.

.g.% ango% 7ose% "ahlia% 2amboo.

2ased on the habit% nature and height of the stem and duration of life cycle% angiosperms can

be distinguished into herbs% shrubs and trees.

,erbs

are small plants with a soft and green stem. They reach a height of not

more than five feet and are mostly annuals or biennials.

+hrubs

are woody perennial plants that may reach a height of five to ten feet.Stem is often profusely branched giving a bushy appearance.

!rees

are woody perennials which reach considerable heights. The stem is hard,

woody and is called trunk. It may be unbranched as in palm trees orextensively branched as in most others.

6ome trees li&e mulberry and oa&% shed all their leaves at the pea& summer or winter season.

6uch trees are described as deciduous. any other trees li&e mango and guava do not shed

their leaves. 6uch trees are described as evergreen.

Ma-or groups of Angiosperms

Irrespective of any system of classification that is being used, angiosperms are

divided into two natural groups called monocotyledons (or monocots) and

dicotyledons (or dicots). This distinction is based on the number of embryonic

leaves (or cotyledons) in the embryo. The following table summarises the

differences between monocots and dicots.


15/17

Angiosperms represent the most advanced group of plants.

The angiosperm plant body consists of an underground root system and an aerial shoot

system. The shoot system contains vegetative parts and reproductive parts.

The root serves two primary functions anchoring and absorption.

There are two types of root system namely tap root system and fibrous root system.

The root may show some modifications for performing specific functions.

The modifications may be for storage of food or for providing mechanical support or

for other vital functions.

The main a$is of the shoot system is called a stem. 't is the ascending portion of the

plant body.

The stem bears distinct nodes and internodes. 2ranches% leaves and buds may arise at

the nodal regions.

The stem may be erect and strong or may be wea&. The wea& stem

may be of a prostrate% decumbent% creeping% twining or climbing type.

Apart from its regular functions% the stem may show modifications towards variousother functions.

:eaf is another ma?or part of the shoot system. 't is a lateral outgrowth of the main

stem or a branch mainly meant for photosynthesis.

The leaf has a stal& called petiole% a body called lamina% leaf ape$ and leaf margin.

:eaves are mainly of two types simple leaves and compound leaves. 6imple leaves

have undivided lamina. 'n compound leaves% the lamina is divided into leaflets.

The compound leaves can be either pinnately compound or palmately compound.Pinnately compound leaves may be unipinnate or bipinnate or tripinnate.


16/17

The arrangement of leaves on the stem is &nown as phyllota$y. Three types are

common alternate% opposite and whorled.

:eaves may sometimes be modified into tendrils or spines.

The collection of flowers in a cluster on the plant is &nown as inflorescence.

't is of two basic types racemose and cymose. 'n racemose type% there is an a$is which

&eeps growing. 't does not end in a flower. Flowers are found in acropetal succession.

;ymose inflorescence has an a$is which does not grow infinitely. 't ends usually in a

flower. Flowers are produced in basipetal succession.

The racemose and cymose inflorescences can be distinguished into several types each.

There are a few e$amples of inflorescences which are described as special types.

Flower is the reproductive structure of a plant body. A flower has functional parts

arranged in four whorls caly$% corolla% androecium and gynoecium.

;aly$ consists of leaf li&e structures called sepals while corolla consists of brightly

coloured structures called petals. These two are together described as non!essential

whorls of the flower which have a protective and complimentary role.

6ometimes the non!essential whorls may be represented by a single structure called

perianth with units called tepals.

The arrangement of sepals and petals in the bud condition% is &nown as aestivation. 't

is of , different types such as valvate% contorted*twisted-% imbricate and uincuncial.

The essential whorls of a flower are represented by androecium and gynoecium.

Androecium is the male whorl of the flower. 't consists of functional units called

stamens containing anthers where pollen grains are formed.

5ynoecium is the female whorl of the flower. 't consists of functional units called

carpels which enclose ovules.

The manner of attachment of the ovules inside the ovary is called placentation.

arginal% a$ile% parietal and basal types of placentation are very common.

Pollination is the process by which pollen grains are transferred from the anther to the

stigma of the same flower *self pollination- or another flower *cross pollination-.

;ross pollination is brought about by agents such as wind% water and animals%

especially insects.

Pollination is followed by fertilisation. 'n angiosperms it is described as double

fertilisation and triple fusion.


17/17

After fertilisation the ovule is transformed into the seed and the ovary is transformed

into the fruit.

Angiosperm fruits can be distinguished into three types3 simple fruits% multiple fruits

and composite fruits.

6imple fruits are those which develop from morocarpellary or polycarpellary

syncarpous gynoecium. They can be either fleshy or dry. "ry fruits can be either

dehiscent or indehiscent.

ultiple fruits develop from polycarpellary% apocarpous gynoecium.

IZZAT Angiosperma

Documents

Transcript of IZZAT Angiosperma