Transcript 20.2 Classification of Plants

20.2 Classification of Plants
KEY CONCEPT
Plants can be classified into nine phyla.
20.2 Classification of Plants
Mosses and their relatives are seedless nonvascular
plants.
• Nonvascular plants grow
close to the ground to
absorb water and nutrients.
• Seedless plants rely on freestanding water for
reproduction.
• Liverworts belong to phylum
Hepatophyta.
– often grow on wet rocks
or in greenhouses
– can be thallose or leafy
20.2 Classification of Plants
• Hornworts belong to phylum Anthocerophyta.
– found in tropical forests and along streams
– flat, lobed body with little green “horns”
20.2 Classification of Plants
• Mosses belong to phylum Bryophyta.
– most common seedless nonvascular plants
– sphagnum moss commonly used by humans as “peat”
20.2 Classification of Plants
Club mosses and ferns are seedless vascular plants.
• A vascular system allows club mosses and ferns to grow
higher off the ground.
• Both need free-standing water for reproduction.
• Club mosses belong to phylum Lycophyta.
– not true mosses
– oldest living group
of vascular plants
20.2 Classification of Plants
• Ferns and their relatives belong to phylum Pterophyta.
frond
fiddlehead
– whisk ferns and horsetails are close relatives of ferns
– ferns have large leaves called fronds
20.2 Classification of Plants
Seed plants include cone-bearing plants and flowering
plants.
• Seed plants have several advantages over their seedless
ancestors.
– can reproduce without free-standing water, via
pollination
– pollination
occurs when
pollen meets
female plant
parts
– seeds
nourish and
protect plant
embryo
– seeds allow plants to disperse to new places
20.2 Classification of Plants
• Gymnosperms do not have seeds enclosed in fruit.
– most gymnosperms are cone-bearing and evergreen.
– the cone is reproductive structure of most
gymnosperms.
– pollen is produced
in male cones.
– eggs are produced
in female cones.
– seeds develop on
scales of female
cones.
20.2 Classification of Plants
• Cycads are gymnosperms in phylum Cycadophyta.
– look like palm trees with large cones
– grow in tropical areas
20.2 Classification of Plants
• Ginkgos are gymnosperms in phylum Ginkgophyta.
– only one species alive today, Ginkgo biloba
– grown in gardens and used in urban landscaping
20.2 Classification of Plants
• Conifers are gymnosperms in phylum Coniferophyta.
– most common
gymnosperms alive
today
– includes pines, spruce,
cedar, fir, and juniper
20.2 Classification of Plants
• Angiosperms have seeds enclosed in some type of fruit.
– A flower is the reproductive structure of angiosperms.
– A fruit is a mature ovary of a flower.
• Angiosperms, or flowering plants, belong in phylum
Anthophyta.