Section 3: Seed Plants

Key Ideas What are the two groups into which seed plants are classified? What characterizes reproduction in seed plants? What are the four major groups of living gymnosperms? What characterizes reproduction in a conifer?

Kinds of Seed Plants Gymnosperms Seed plants whose seeds do not develop within a fruit. Most of these seeds develop in a cone Greek words gymnos, meaning “naked,” and sperma, meaning “seed” Angiosperms seed plants whose seeds develop enclosed within a fruit Fruits develop from part of a flower Flowering plants Greek words angeion, meaning “case,”

Visual Concept: Characteristics of Vascular Plants With Seeds

Reproduction in Seed Plants do not require water to reproduce sexually. greatly reduced gametophyte and a dominant sporophyte. female gametophyte develops inside an ovule, a multicellular structure that is part of the sporophyte

Reproduction in Seed Plants, continued The male gametophyte of seed plants develops inside a pollen grain. The transfer of pollen grains from the male to the female reproductive structures is called pollination. The fusion of an egg and sperm is called fertilization. After fertilization, the ovule is called a seed and contains an embryo.

Reproduction in Seed Plants, continued Seeds are dispersed, or scattered, from the parent plant to locations where the embryos in the seeds develop into new sporophytes. Dispersal may prevent competition for water, nutrients, light, and living space between parents and offspring. Many seeds have structures that help wind, water, or animals carry them away from their parent plant.

Gymnosperms There are four major groups of gymnosperms: conifers, cycads, ginkgoes, and gnetophytes. Conifers are the most familiar gymnosperms. needle-like leaves pine trees and redwoods.

Visual Concept: Characteristics of Gymnosperms

Visual Concept: Types of Gymnosperms

Life Cycle of a Conifer dominant sporophyte wind pollination the development of seeds in cones. The gametophytes develop in cones circles of modified leaves called scales. Many gymnosperms produce both female and male cones on the same plant.

Visual Concept: Life Cycle of Conifers