What’s a Plant?

Kingdom Plantae

• Eukaryotic

• Multicellular

• Have a cell wall with cellulose

• Are autotrophic (use photosynthesis)

• Plants first existed in water

• As the environment became drier they adapted

to live on land

• The fossil record provides little information

about plant evolution, as soft tissue does not

fossilize well.

Plant Adaptations to Land

Plants

• Cells needed to obtain water

• Support systems to hold leaves up to expose as much

as possible to the sun for food production

• A transport system is necessary to move water and

nutrients to all cells

• Gas exchange occurs with little water loss

• Reproduction must prevent drying out of gametes or

embryos.

• There are four main groups of land plants:

• Bryophytes: Mosses, Liverworts and Hornworts

• Pteridophytes: Ferns, Clubmosses, and Horsetails

• Gymnosperms: Cone bearing seed plants

• Angiosperms: Flowering seed plants

Bryophytes • Includes: Mosses, Hornworts, Liverworts

• Must live in wet areas

• No vascular system (transport system)

• Water transport by osmosis

• No true leaves or stems or roots (these structures

must contain vascular tissue)

• Only a few centimeters tall

• No protective covering to prevent H2O loss

• Need water for reproduction

Vascular Plants

• All have specialized tissue called vascular

tissuewhich transports water and photosynthesis

products

• Xylem – transports water

»Tracheid cells

• Phloem – transports nutrients

Characteristics of Vascular Plants

• True roots

• True leaves

• Photosynthetic with vascular tissue as veins and

a waxy covering called the cuticle

• True vascular tissue called the vascular

cylinder

Pteridophites • Includes: Ferns, Horsetails

• Independent of water - can live on dry land

• Ferns have true vascular tissue, strong roots,

• creeping underground stems called rhizomes

and large leaves called fronds

Gymnosperms • Includes: Conifers, Cycads, Gingko biloba

• Gymnosperm means “naked seed”

• Produce seeds in cones

• Vascular plants

• Have true roots, leaves and stems

• Seeds are not protected

• Wood produced by gymnosperms

• Gymnosperms have a very efficient vascular

system

– Xylem - wood of a tree

– Phloem - bark of the tree

Angiosperms Include:

• All flowering plants!

• Angiosperm means “covered seed”

• Have flowers

• Have fruits with seeds

• Have vascular tissue

• True roots, stems and leaves

• Live everywhere – dominant plants in the world

• 260,000 species (88% of Plant Kingdom)

• Angiosperms are the most successful and

advanced plants on earth

Angiosperm Reproduction

• Male sex organ is the stamen

• anther – organ that produces pollen

• filament - holds the anther

• Female sex organ is the the carpel

• Stigma - sticky surface that traps pollen

• Style - connects stigma to ovary

• Ovary is the enlarged base of carpel that

contains the ovules