What is a plant?

Plants are... Multicellular Have cell walls Photosynthetic Growth occurs in modules or “pieces” Reproduction –Asexually –Sexual via spores or seeds

Reproduction Asexual –Rhizomes (iris) –Bulbs or corms (daffodils) –Runners or stolons (Bermuda grass, strawberries) Sexual –Spores (mosses, liverworts and ferns) –Seeds (gymnosperms, and angiosperms)

Cellular components of plants Cell wall made of cellulose Nucleus containing DNA Mitochondria Vacuole Chloroplasts

Photosynthesis “the bottom line” Plant absorbs sunlight Triggers reaction to create energetic molecules (ATP, NADPH) Energetic molecules are used to build sugars from CO 2 Sugars are transported to the rest of the plant for energy metabolism

Plant growth Many plants have continuous growth Growth occurs in discrete places Primary growth is the making of new tissues Secondary growth is the enlarging of older tissues

1) Stamen male reproductive parts –Anther contains pollen –Filament stem-like portion of the stamen that holds the anther erect 2) Carpel female reproductive parts of the flower –Stigma sticky end part of the carpel fo pollen attachment –Style the stalk that raises the stigma out of the flower –Ovary area in which the ovules are kept ovary wall will develop into fruit

3) Ovule structure that will develop into seed after fertilization 4) Calyx outer most portion of the flower, usually showy –Petals usually the colorful portion of the flower collectively the petals are called the corrolla –Sepals outermost part of the flower covers the developing bud often green, but sometimes colored like the petals as in lillies

What is a fruit? A mature ovary Found only in angiosperms Protects the seeds by enlarging the ovary wall Aids in dispersal of seeds

Plant Diversity

Bryophytes the most simple land plants Liverwort Moss

Ferns Ferns are seedless vascular plants.

Gymnosperms Have seeds, but lack ovaries to protect the developing seeds Conifers are ubiquitous cone bearing trees. (source of most of our lumber)

Gymnosperm Gnetophytes live only in southwestern Africa

Angiosperms are the flowering plants

Vascular vs. Non-vascular Non-vascular –Water movement by osmosis –Solutes move by diffusion –Plants not very large, all parts must be near their water source Vascular –Water and solutes moved through special cells called xylem –Sugar transported by special cells called phloem –Plants can be 300’ tall and parts can be distant from water source

Vascular tissues Xylem –Water conducting tissue –Dead at maturity Phloem –Sugar conducting tissue –Living at maturity

Vascular plant body Roots Stems Leaves

Roots 1) Root cap is gelatinous 2) Area of cell division 3) Area of cell elongation 4) Mature root has root hairs

Stems 1) Have specialized cells with thickened cell walls for support 2) Provide height for reaching sunlight 3) Pipe water from roots to shoots and sugars from leaves to roots

Leaf cross section Leaves are used to gather light and accomplish photosynthesis Waxy cuticle Epidermal cells Many chloroplasts Have stomates

Water uptake Water is moves into the roots Enters the xylem tissue Through adhesion to the cell walls, cohesion to other water molecules and water tension water moves up the plant as water evaporates from the leaves

Plant adaptations to life on land 1) Development of spores with durable protective walls allowing the spores to tolerate dry conditions 2) Waxy cuticle to reduce water loss across cell walls 4) Development of a vascular system allowing plants access to water deep in the soil 3) Stomata, which are pores in the cuticles of leaves which can open and close 5) Specialized cells with thickened cell walls for rigid support