Introduction to Plants

A. Obstacles to living on land Harsh ultraviolet light  oxygen produced in oceans converted to ozone Absorbing minerals  mutualism with fungi, similar to mycorrhizae Conserving moisture  Waxy cuticle, with pores called stomata Reproducing on land  sperm protected in pollen grains

Pollen Grains

B. Vascular Tissue and Seeds Tissues to conduct materials within a plant. Xylem moves water and dissolved minerals from roots to leaves. Phloem moves carbohydrates from leaves to roots. A seed contains the embryo of a plant. Seeds provide advantages such as protection, nourishment, dispersal, and delayed growth.

Cladogram of Plant diversity Angiosperms Monocots Dicots Gymnosperms (conifers) Ferns Fruits and flowers Mosses Seeds Vascular tissue

C. Phyla of Living Plants Nonvascular plants include mosses, liverworts, and hornworts. These require water for reproduction, and are small in size. Mosses do not make seeds

Mosses do not have xylem or phloem

Vascular, Seedless plants include ferns and horsetails Vascular, Seedless plants include ferns and horsetails. These have xylem and phloem, but do not produce seeds.

Gymnosperms (with seeds) are primarily the conifers and cycads Gymnosperms (with seeds) are primarily the conifers and cycads. These rely on wind for pollination

Angiosperms (with flowers and fruits) are the most numerous plants

D. Alternation of Generations Plants alternate between a haploid gametophyte that produces gametes and a diploid sporophyte that produces spores

E. Evolution of flowers Flowering plants are more efficient than conifers, because animals often carry the pollen.

Flower have four basic structures: A. Sepals – modified petals, protect flower while it is a bud

Petals – may be scented and/or colored to attract animals

Stamen – male reproductive structure, with anther and filament Pistil – female reproductive structure, with stigma, style, and ovary. Fertilized egg develops within ovary, becomes a seed.

A cotyledon is a leaf-like structure that stores food for the embryo Angiosperms are divided into two classes: Plants with one cotyledon are called monocots. Plants with two cotyledons are called dicots.

Monocots Dicots Embryo One cotyledon Two cotyledons

Monocots Dicots Flowers flower parts are in multiples of 3 flower parts are in multiples of 4 or 5

Monocots Dicots Stems xylem and phloem is scattered Xylem and phloem is in a ring pattern

Monocots Dicots Leaves Veins are parallel Veins are branching

Monocots Dicots Roots Fibrous – numerous roots of approx. the same length Taproot – a main root with small lateral roots

Monocots Dicots Examples Wheat, Rice, Grass, Daffodils Peas, Radishes, Lettuce, Carrots, most trees (apple blossom below)

Monocot or dicot?

Monocot or dicot?

Monocot or dicot?

Monocot or dicot?