Seed Plants

Seed Plants Seed Plants are divided into 2 groups: Gymnosperms Bear seeds in cones Conifers, cycads, ancient ginkgoes, and gnetophytes Angiosperms Also called flowering plants Bear their seeds within a layer of tissue that protects the seed (fruit) Grasses, flowering trees and shrubs, and all wildflowers

Reproduction of Seed Plants Adaptations allowed seeds to reproduce without water Flowers or cones Transfer of sperm by pollination Protection of embryos in seeds

Cones and Flowers Gametophytes of seed plants grow and mature within sporophyte structures Cones: seed-bearing structures of gymnosperms Flowers: seed bearing structures of angiosperms

Pollen Entire male gametophyte contained in a pollen grain Carried to female reproductive structure by wind, insects, or small animals Transfer of pollen from the male reproductive to female reproductive is called pollination.

Seeds Seed is an embryo that is encased in a protective covering and surrounded by a food supply Embryo=organism in early stage of development Seed Coat Surround and protects the embryo Prevents drying out

Structure of Seeds

Evolution of Seed Plants Years ago, land wetter Over years, land dried out causing mosses and ferns to have to adapt Seed plants eventually evolved from ferns

Gnetophytes 70 species Reproductive scales in cones

Cycads Palm-like plants that reproduce with large cones

Ginkgoes One species=Ginkgo biloba

Conifers Most common gymnosperm Includes pine, spruces, firs, cedars, and redwoods Most retain leaves throughout the year Why?

Angiosperms Flowering Plants Develop unique reproductive organs known as flowers Flowers contain ovaries, which surround and protect the seeds Angiosperm means: “Enclosed Seed”

Angiosperm Reproduction Most reproduction occurs with animal/insect pollination Once pollinated, the ovary develops into a FRUIT Wall of tissue surrounding the seed

Angiosperm Parts

Diversity of Angiosperms Incredibly diverse group Many ways of categorizing them: Monocot or Dicot Woody or Herbaceous Annuals, Biennials, or Perenials Categories may overlap

Monocot Monocots have: Single Cotyledon Parallel veins Cotyledon: first leaf or the first pair of leaves produced by the embryo of a seed plant Parallel veins Floral Parts often in multiples of 3 Vascular Bundles scattered throughout stem

Monocots

Dicot Dicots have: Two Cotyledons Net Venation (branched veins) Floral parts in multiples of 4 or 5 Vascular Bundles arranged in a ring

Dicots

Other Categories Annuals-Plants that complete a life cycle within one growing season Ex) Marigolds, petunias, wheat Biennials-Complete their life cycles in two years Ex) Parsley, celery Perennials-Flowering plants that live more than two years Ex) Palm trees, maple trees, asparagus, grasses