Chapter 30: Plant Diversity II: The Evolution of Seed Plants

Vocabulary flashcards covering the evolution, characteristics, and diversity of seed plants (Gymnosperms and Angiosperms) based on Chapter 30 lecture notes.

Seed

Consists of an embryo and nutrients surrounded by a protective coat, originating about $360\text{ million years ago}$ ($360\text{ MYA}$).

Megaspore

A type of spore in heterosporous plants that gives rise to the female gametophyte.

Microspore

A type of spore in heterosporous plants that gives rise to the male gametophyte.

Reduced gametophytes

Microscopic gametophytes that develop within the walls of spores retained within tissues of the parent sporophyte, protecting them from environmental stress.

Ovule

Consists of a megasporangium ($2n$), megaspore ($n$), and protective integument; it contains the female gametophyte (egg).

Pollen grain

The male gametophyte representing an adaptation for life on land that eliminates the need for water in fertilization.

Pollen tube

A structure produced by a germinated pollen grain that discharges sperm into the female gametophyte within the ovule.

Gymnosperms

Non-flowering plants that bear "naked" seeds, typically on sporophylls that form cones.

Angiosperms

Flowering plants with "covered seeds" found in fruits, which are matured ovaries.

$$Archaeopteris$$

A heterosporous tree from the late Devonian period ($380\text{ MYA}$) with a woody stem that did not bear seeds.

$$Elkinsia$$

A genus of fossil plants from $360\text{ million years ago}$ that provides the earliest evidence of seed plants.

Progymnosperms

Plants from the late Devonian that fossils reveal had some characteristics of seed plants.

Age of Cycads

A term for the Mesozoic era, from $252$ to $66\text{ MYA}$, when gymnosperms like cycads dominated terrestrial ecosystems.

Phylum Cycadophyta

Gymnosperms known as sago palms that have palm-like leaves and flagellated sperm, with individual plants being either male or female.

Phylum Gingkophyta

A phylum represented by the single extant species $Ginkgo\text{ biloba}$, a broad-leaf deciduous conifer with fanlike leaves.

Phylum Gnetophyta

A gymnosperm phylum consisting of three genera: $Gnetum$, $Ephedra$ (Mormon Tea), and $Welwitschia$.

Phylum Coniferophyta

The largest phylum of gymnosperms, including pines, firs, junipers, sequoias, and bald cypress.

Evergreens

Conifers that can carry out photosynthesis all year round.

Sepals

Modified leaves in a flower that enclose the flower structure.

Petals

Brightly colored modified leaves in a flower that attract pollinators.

Stamens

The pollen-producing reproductive structures of a flower.

Carpels

The ovule-producing reproductive structures of a flower.

Fruits

Mature ovaries that protect seeds and enhance their dispersal by wind, water, or animals.

Double fertilization

A process in angiosperms where one sperm fertilizes the egg and a second sperm combines with two nuclei to initiate the development of endosperm.

Endosperm

Tissue that nourishes the developing embryo within an angiosperm seed.

In-and-out of water hypothesis

The hypothesis that the common ancestor of angiosperms was an aquatic plant that reinvaded terrestrial habitats.

Evo-Devo hypothesis

The hypothesis that flowers resulted from a mutation in developmental genes that brought separate pollen-producing and ovule-producing structures together.