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