Seed Plants: Evolution and Classifications

Vocabulary-style flashcards covering the evolution, phyla, and structural characteristics of seed plants (Gymnosperms and Angiosperms).

Progymnosperms

The spore-bearing plants from which seed plants evolved approximately $305-465\,MYA$.

Seed

An embryo protected by an integument (sporophyte tissue) that hardens into a seed coat and contains a food supply.

Dormancy

An evolutionary advantage of seeds that allows the "clock to be stopped" to survive harsh periods before germinating.

Pollen

The male micro-gametophytes that allow for the dispersal of sperm without a dependency on water.

Megagametophyte

The female gametophyte that develops within an ovule and is enclosed within diploid sporophyte tissue in angiosperms.

Gymnosperms

Plants characterized by "naked seeds" that lack flowers and fruits, with the ovule exposed on a scale.

Coniferophyta

The most familiar gymnosperm phylum, including pines, spruces, firs, and cedars.

Coastal redwood

Recognized as the tallest living vascular plant within the phylum Coniferophyta.

Bristlecone pine

Recognized as the oldest living tree within the phylum Coniferophyta.

Cycadophyta

Slow-growing gymnosperms of tropical and subtropical regions that resemble palm trees and can have female cones weighing up to $45\,kg$.

Gnetophyta

The only gymnosperm phylum that contains vessels in their xylem; includes the genera Welwitschia, Ephedra, and Gnetum.

Dioecious

A reproductive state where male and female reproductive structures form on different trees, as seen in the species Ginkgo biloba.

Monocots

Angiosperms characterized by one cotyledon, parallel leaf veins, scattered stem vascular tissue, and floral parts in multiples of $3$.

Eudicots

Angiosperms characterized by two cotyledons, network/branched leaf veins, vascular tissue arranged in a ring, and trisulcate pollen.

Androecium

The collective term for the stamens of a flower, which include the anther and filament.

Gynoecium

The collective term for the carpels of a flower, consisting of the stigma, style, and ovary.

Secondary growth

The process of expanding a plant's girth and creating wood, which occurs in eudicots but not in monocots.

Wood

A material formed by proliferating xylem during secondary growth.

Apical meristems

The regions of roots and shoots where all plants undergo primary growth.