-lack enclosed chambers where angiosperm seeds develop
-More suited to drier climate
-Vegetation consist mostly conifers & cycads(2
divisions of gymnosperms)
-When climate cooler-gymnosperm still persisted
Division-Cycadophyta
-resemble palms
-bear naked seeds on sporophylls
Division Ginkgopyta
-fanlike leaves(turn gold & decidios in autumn)
(unusual trait for gymnosperm)
Division Gnetophyta
Genus Gnetum
-grows in tropics as trees/vines
genus Gnetophyta
-shrub in American deserts
Division Coniferophyta(conifers)
-conus"cone" ferre"to carry"
-cone, structure of scalelike sporophylls
-includes:pines,firs,spruces,larches,yews,junipers,
cedars,cypresses, & redwoods
-most large plants
-dominate vast forested regions of Norhtern Hemisphere
-growing season relatively short b/c lattitude &
longitude
-Nearly all are evergreens(retain leaves throughout
year)
Pines & furs adapted to dry conditions(by needle
shaped leaves)
-Thick cuticle covers leaf & stomata located in pits
-coniferous trees among tallest,largest, & oldest on
earth
-tracheids-cells that conduct water(elongated,tapered
cell,functions in mechanical support & movement)
Phylum: Angiosperms
Division:Anthophyta
Class:Moncotyledones(monocots)
-ex:)lilies,orchids,yuccas,palms,& grasses(include
lawn grass),sugar cane,& grain crops(corn,wheat, rice
& others)
-seeds store food in endosperm
Class: Dicotyledones(dicots)
-ex:)roses,peas,buttercups,sunflowers,oaks,& maples
-transfer most of nutrients from endosperm to
cotyledons
-vessel elements-shorter,wider cells arranged end to
end, form continuous tubes,more specialized than
tracheids for transporting water,but less specialized
for support)
-xylem reinforced by second cell type-
fiber,specialized for support
-flower-reproductive structure
-insects & animals transfer pollen from 1 flower to
another(makes pollination less random than wind-
pollinated)
-sepals-usually green enclose flower before it
opens
-petals-aid in attracting insects & other
pollinators
-stamens-"male" flower parts,has filament-stalk, &
anther-terminal sac,where pollen,(pollen grains-
immature male gametophyte(each has 2 haploid cells))
produced
-carpel-female" flower parts,at tip has stigma-
recieves pollen,syle-leads to ovary-protects ovules-
develops into seeds after fertilization(embryo sac-
female gametophyte),has only few cells
-enclosure of seeds w/in ovary,distinguishes from
gymnosperms
-fruit-mature ovary,helps protect & disperse seeds
-most use animals to carry seeds
-heterosporous,same as all seed plants
-flower of sporophyte produces microspores(form male
gametophytes) & megaspores(form female gametophytes)
-self & cross pollinate
-double fertilization-both sperm nuclei of angiosperm
pollen fertilize cells in embryo sac(1 sperm nucleus
unites w/ egg,form diploid zygote,other nucleus fuses
w/ 2 nuclei in center cell of embyro sac)
cotyledons-zygote develops into sporophyte embryo w/ 1
or 2 seed leaves & rudimentary root(monocot-1 seed
leaf, dicot-2 seed leaf)
-endosperm-tripod tissue made by tripod nucleus in
center of embryo sac by dividing repeatedly -rich in
starch & food reserves
-Seed-mature ovule,have embryo,endosperm,& seed coat
derived from integuments(outer layers of ovule)
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