Gymnosperms and Seed Plant Evolution

This set of flashcards covers key vocabulary and concepts related to gymnosperms and the evolution of seed plants, helping students understand their characteristics, life cycles, and importance.

Gymnosperms

Non-flowering seed plants that produce exposed or 'naked' seeds.

Angiosperms

Flowering seed plants that have seeds enclosed within an ovary.

Ovule

A structure consisting of a megasporangium (nucellus) covered by an integument, where fertilization occurs.

Heterospory

The production of two distinct types of spores: megaspores and microspores, crucial for seed and pollen formation.

Microgametophyte

The male gametophyte that develops from microspores and forms pollen grains.

Megagametophyte

The female gametophyte that develops from megaspores and is retained within the ovule.

Pollen Tube

A tubular structure that forms from a pollen grain and carries sperm to the egg within the ovule.

Archegonia

Female reproductive structures that contain the egg cell; shares primitive features with seedless plants.

Polyembryony

The phenomenon where multiple embryos develop from a single fertilized egg in some seeds.

Progymnosperms

Early seed plants with characteristics intermediate between seedless vascular plants and seed plants, existing around 290 million years ago.

Phylum Coniferophyta

The largest group of gymnosperms including pines, firs, and spruces, known for their cone-bearing reproductive structures.

Phylum Cycadophyta

The second-largest group of gymnosperms, characterized by palm-like plants predominantly found in tropical areas.

Phylum Ginkgophyta

The only living member is Ginkgo biloba, which is deciduous and has unique fan-shaped leaves.

Phylum Gnetophyta

Includes three genera (Ephedra, Gnetum, Welwitschia) with features resembling angiosperms such as vessel elements.

Seed Coat

Protective outer layer of a seed resulting from the integument that surrounds the ovule.

Micropyle

The opening at the apex of an ovule that allows pollen to enter for fertilization.

Dispersal

The process by which seeds are spread from the parent plant to promote germination and growth in new locations.

Fertilization in Pines

Occurs approximately 15 months after pollination when a pollen tube fertilizes the egg.

Pine Life Cycle

The developmental process involving the formation of pollen, fertilization, and eventual seed development in pines.

Nucellus

The central tissue of the ovule that contains the megasporocyte and other structures necessary for seed development.