Unit 2 Part 5 | Seed Plants | Biodiversity

Seed Plants

plants that produce seeds for reproduction

Ovule

A structure that develops within the ovary of a seed plant and contains the female gametophyte.

Pollen Grains

In seed plants, a structure consisting of the male gametophyte enclosed within a pollen wall.

Heterospory

the production of two distinct types of spores by different structures

Pollination

The transfer of pollen from male reproductive structures to female reproductive structures in plants

Seed evolved into:

a dormant embryo with surrounding nutrients protected from environmental conditions. Seeds replaced spores as dispersal agents, using wind, water, or animals for more efficient dispersal.

Secondary Compounds

toxic chemicals produced in plants that discourage herbivores ; Used for medical treatments as well.

Gymnosperms

A plant that produces seeds that are exposed rather than seeds enclosed in fruits

Cycadophyta

“Cycads” (320mya)

130 extant species

Diverse during the Mesozoic

Palm-like leaves

Highly toxic compounds

May reach 18 feet in height

Reproduce through cones

Dioecious

Male plants with male cones Produces sperm

Female plants with females cones Produces ovules

Beetles are important pollinating agents

Ginkgophyta

•Mostly extinct

•Only surviving species:

Ginkgo biloba

•Fan-like leaves

•Dioecious

Gnetophyta

•characteristics of gymnosperms and flowering plants

•Fleshy leaves

•Strobilli are similar to some inflorescences

•3 genera Gnetum Ephedra Welwitschia

Coniferophyra

- oldest, tallest, largest trees

- needles are leaves adapted to drought conditions

- Important for lumber, paper, etc

- examples: Sequoia (red wood), pines, junipers, cypress, etc.