Mr Bastin - ZooBot - Plant Classification

Gametophyte stage

all cells are haploid

-single set of unpaired chromosomes

-abbreviated as n

make gametes through mitosis

Sporophyte stage

diploid

-cells have 2 complete sets of chromosomes from both parents

-contain both chromosomes for each homologous pair (genes for the same trait)

-abbreviated as 2n

produces haploid spores through meiosis

Plant Taxonomic Ranking

Domain: Eukarya

Kingdom: Plantae

Divided into groups based on

-water-conducting tissues

-seeds

-flowers

Nonvascular Plants

(mosses, liverworts, and hornworts)

-gametophyte phase larger

-sporophyte physically connected to gametophyte

lack vascular tissue

-no xylem cells to conduct water

-require water for reproduction

>sperm must swim through water to reach egg

>>>thus occurs only in moist habitats

Divisions of Nonvascular Plants

Division Bryophyta (mosses), division Hepatophyta (liverworts), division Anthocerophyta (hornworts)

Division Bryophyta

mosses

-gametophyte phase most obvious

-produces "stalks" w/ capsule (sporophyte) to reproduce

Division Hepatophyta

liverworts

-gametophytes look like flat leaves on ground

-sporophytes resemble tiny umbrellas

-can reproduce asexually via gemmae

Division Anthocerophyta

hortworts

-gametophytes similar to liverworts

-sporophyte look like tiny green horns

Vascular Plants

(conifers, flowering plants)

-sporophyte dominant (larger)

-gametophyte often reduced to small structure within sporophyte

>In flowering plants

>>male gametophyte develops inside pollen grain

>>female gametophyte develops inside ovary

-have xylem tissue, roots, stems, leaves

Types of Vascular Plants (seedless vs. seeded)

Seedless: Division Psilophyta (whisk fern), division Lycophyta (club mosses), division Sphenophyta (horsetails), division Pterophyta (ferns)

Seeded:

-Gymnosperms: Division Cycadophyta (cycads), division Ginkgophyta (ginkgo), division Gnetophyta (welwitschia), division Coniferophyta (conifers

-Angiosperms: division Anthophyta (flowering plants)

Seeded Vascular Plants

Gametophytes grow within cones or flowers of sporophyte

-male gametophyte = pollen grain

Gymnosperms

naked seeds (seeds on surface of cones

Angiosperms

seeds enclosed in fruit

Division Cycadophyta

cycads

-palmlike

-large cones

Division Ginkgophyta

ginkgo

-only 1 species

Division Gnetophyta

Welwitschia

-unique desert plants

Division Coniferophyta

conifers

-pines, cedars, redwoods, etc.

-needles adapted to dry conditions

-most evergreens

Division Anthophyta

flowering plants

-angiosperms

-flowers = reproductive organs

>ovary develops into fruit w/ seeds

-numerous ways to categorize