chapter 26- seed plants

seed plants

spermatophytes (vascular)

what are the 2 categories under spermatophytes

gynosperms and angiosperms

seed plants first appeared

305-465 mya, gymnosperms THEN angiosperms

timeline

first land plants, first vascular plants, first seed plants, first gymnosperms, gymnosperm forests replace fern forests, cycads and conifers dominate, flowering plants

embryophytes

land plants

embryo

produced from the diploid zygote, grows into sporophyte (2n) when seed germinates

seed

offers embryo protection and nourishment

female gametophyte

develops in ovule (has egg and endosperm producing cell-supports growth), enclosed within diploid sporophyte tissue in angiosperms

male gametophyte

within pollen grains (has sperm of the plant), protected from desiccation, not dependent on water to reach female organs

desiccation

extreme no water

mosses and nonvascular plants reproduction

gametophyte- dominant, sporophyte- reduced and dependent on gametophyte for nutrition, sporophyte (2n) and gametophyte (n) grows on top of main plant body

ferns and other seedless vascular plants reproduction

gametophyte- reduced and independent (free living n), sporophyte- dominant (2n)

seed plants reproduction (gymnosperm)

gametophyte- reduced (microscopic) dependent on sporophyte for nutrition, sporophyte- dominant, female gametophytes- inside ovulate cone, male gametophytes inside pollen cones

seed plants reproduction (angiosperm)

same as gymnosperm, female gametophyte- inside bulb of flower, male gametophyte- inside tall stalks of flowers

seed plants are

heterosporous- megaspores for female gametophytes and microspores for male gametophytes happens in sporangium

what is the advantage of gametophytes maturing in sporangia?

highly reduced in size, protected from drying and UV

seed

develops in fertilized ovule= integument+megasporangium+megaspore

megaspore germinates inside ovule to develop

tiny female gametophyte, produces eggs then will be fertilized

seed structure

embryo, food supply, seed coat (embryo is 2n)

pollen grains

male gametophyte surrounded my pollen wall (partly from sporophyte), long dispersal, tough and resistant, does not need water for fertilization

sporopollenin

protects pollen grains (inside pollen wall)

pollination

transfer of pollen to part of the seed plant that has ovule

fertilization process from pollen grains side

pollen grain germinates, pollen tube, sperm discharged into female gametophyte

gymnosperm characteristics

naked seeds (kinda protected by sporophyls), pollination by wind, vascular system (tracheids), alternation of generations, reduced gametophytes, dominant sporophyte, heterosporous, reproductive organs are cones or strobili, monoecoius or dioecious

where do female and male cones grow on gymnosperms (conifers)

males on lower branches and females on upper branches

gymnosperms phyla

coniferophyta, cycadophyta, gnetophyta, ginkophyta, non flowering and naked seed (ex- conifers, cycad, ginkgos)

angiosperm phyla

anthophyta, flowering and covered seed (ex-all flowering plants)

coniferophyta

conifers, most diverse, have cones (pollen and ovulate cones), high altitudes, evergreen with needles

examples of coniferophyta

pine, fir, spruce, sequoia

cycadophyta

cycads, fern like, radiate from central stem, central female and male cones, flagellated sperm, beetles are involved for polination

ginkgophyta

ginkgos, one tree- ginkgos biloba, herbal medicine, flagellated sperm, fan shaped leaves, strobili

gnetophyta

gnetophytes, 3 genera: Ephedra (U.S deserts), Gnetum (tropics), Welwitchia (deserts), strobili, male sperm not mobile

ephedera (gntephyta)

used for herbal medicine

angiosperms key innovations

flowers and fruits

flowers

structure to facilitate sexual reproduction (due to pollinators)

male part of flower

anther and filament

female part of flower

stigma, style, ovary

sepals

green petals close to flowers

stamen

male part (filament and anther)

carpel

female part (stigma-sticky tip, style, ovary, and ovules)

angiosperm male life cycle

microsporangia, male sporocytes (2n), microspores (1n), pollen grain (n)

pollen grains

1 generative cell, 1 tube cell

angiosperm female life cycle

ovule, megasporangium, megasporocyte (2n), 4 megaspores(n), only large megaspore survives, 3x mitosis to get 3 cells at one pole to become egg and 2 synergids (the other 3 cells are antipodal cells)

center cell

2 polar nuclei

double fertilization with 2 sperm nuclei

one fuses with egg to get zygote (2n) and one fuses with polar nuclei to get endosperm (3n) for food supply in seed

fruit

mature ovary of flower thickens around seeds, protects seeds and enhances seed dispersal

monocots examples

orchids, palms, lillies, grasses

eudicots examples (dicots)

oaks, peas, roses, potatoes

tissues rarely found in monocots

true woody tissues

eudicots can be

non woody (herbaceous) or woody tissues called xylem cells

monocot characteristics

one cotyledon, parallel veins, vascular tissue scattered, fibrous foots (no main root), pollen grain with one opening, flower organs in multiple of 3

eudicot characterisitcs

2 cotyledons, veins are netlike, vascular tissue arranged in a ring, taproot (main root), pollen grain with 3 openings, flower organs in multiple of 4 or 5