Introduction to Plants

What is a Plant?

• Plants provide the base for the food chain• Multicellular eukaryotes that have a cell wall made of

cellulose• Carry out photosynthesis (autotrophs)• Can reproduce without water and can reproduce

asexually or sexually• Plants need:

– Sunlight– Water– Minerals– Carbon dioxide– Movement of water and minerals through tissues

Overview of Plant Kingdom

• Four groups based on three features – water-conducting tissues, seeds, and flowers:

Cone-bearing plants760 species

Ferns andtheir relatives11,000 species

Mosses andtheir relatives15,600 species

Floweringplants235,000 species

Plant Cladogram

Floweringplants

Cone-bearingplants

Ferns andtheir relatives

Mosses andtheir relatives

Green algaeancestor

Flowers; SeedsEnclosed in Fruit

Seeds

Water-Conducting(Vascular) Tissue

Mosses & Their Relatives (Bryophytes)

• Non-vascular plants – they do not have tissues that are specialized to conduct water and nutrients, thus they stay small in size and must live in moist areas

• Depend heavily upon water to survive and reproduce

• Reproduce by spores, NOT seeds• Groups of Bryophytes

– Mosses– Liverworts– Hornworts

Mosses

• Grow in areas with water

• Adapted to nutrient-poor soil

• Tolerate low temperatures

• NO true leaves or stems

• Parts of plant only one cell thick

Rhizoid

Capsule

StalkSporophyte

Gametophyte

Stemlikestructure

Leaflikestructure

Examples of Mosses

Liverworts

• Look like flat “leaves” on ground

• Draw up moisture from surface of soil

Hornworts

• Reproductive structure looks different than liverworts

Human Uses of Mosses

• Sphagnum moss used as a sponge or for decoration

• Peat moss for gardening

Seedless Vascular Plants

• Contain vascular tissue that is specialized to conduct water and nutrients in the plant

• Reproduce by spores, NOT seeds

• Two types of vascular tissue:– Xylem – carries WATER up from roots– Phloem – carries NUTRIENTS up from roots

Ferns & Their Relatives

• Club moss, horsetails, and ferns

• Have true roots, leaves, and stems

Club Mosses

• Small plants that look like miniature pine trees

• MUCH taller (about 12 to 14 inches tall) than true mosses

Horsetails

• Grows one meter tall and looks similar to club mosses

Ferns

• More than 11,000 species

• Strong roots and large leaves called fronds

• Can survive in low light

• Typically have shiny leaves = covered with waxy cuticle = don’t dry out easily = can live in a drier environment than mosses

Examples of Ferns