Chapter 26: Seed Plants Study Guide

Sporophyll

A modified leaf that bears sporangia in seed plants.

Heterospory

The condition of producing two distinct types of spores: microspores that develop into male gametophytes (pollen) and megaspores that develop into female gametophytes.

Sporopollenin

A tough, protective polymer that coats and protects pollen grains and spores.

Microsporangium

A reproductive structure that produces microspores through the meiosis of diploid ($2n$) microsporocytes.

Megasporangium

A reproductive structure that produces megaspores through the meiosis of diploid ($2n$) megasporocytes.

Pollen

The reduced, microscopic male gametophyte of seed plants that produces sperm and a pollen tube.

Seed

A specialized structure consisting of an embryo, food reserves, and a protective coat that aids in embryo protection, nourishment, and dispersal.

Gymnosperms

Seed plants characterized by 'naked seeds' commonly associated with cone scales rather than enclosed within fruits.

Tracheids

Lignified, water- and mineral-conducting cells that serve as the dominant xylem cells in gymnosperms.

Conifers

The dominant gymnosperm group, characterized by needle-like leaves and adaptations to cold, dry, or high-altitude environments.

Cycads

A gymnosperm group with a palm-like appearance found in mild climates, which were common in prehistoric times.

Ginkgophytes

A gymnosperm group represented by a single surviving species, Ginkgo biloba, characterized by fan-shaped leaves.

Gnetophytes

A gymnosperm group that includes plants adapted to arid regions and has an unresolved phylogeny.

Monoecious

A term describing a plant species that bears both male and female reproductive structures (such as cones) on the same individual plant.

Dioecious

A term describing a plant species that bears male and female reproductive structures on separate individual plants.

Microsporocyte

A diploid ($2n$) cell located inside a microsporangium that undergoes meiosis to produce four haploid ($n$) microspores.

Generative cell

A haploid cell inside a pollen grain that divides by mitosis to form two haploid ($n$) sperm cells.

Pollen tube cell

A cell in the pollen grain responsible for generating and elongating the pollen tube.

Megasporocyte

A diploid ($2n$) cell within a megasporangium that undergoes meiosis to produce four haploid ($n$) megaspores, of which only one survives.

Conifer Seed Coat

The protective outer layer of a conifer seed derived from the parental sporophyte, having a diploid ($2n$) ploidy.

Conifer Food Reserves

The nutritive tissue inside a conifer seed derived from the female gametophyte, possessing a haploid ($n$) ploidy.

Angiosperms

Flowering plants characterized by novel derived traits including flowers, seeds enclosed within fruits, and xylem containing vessel cells.

Vessel cells

Specialized xylem conducting cells found in angiosperms that conduct water more efficiently than tracheids.

Sepals

Outer floral organs, often green, that enclose and protect developing flower buds.

Petals

Floral organs that are frequently colorful to attract animal pollinators.

Carpel

The female reproductive organ of a flower (also termed pistil or gynoecium), consisting of the stigma, style, and ovary.

Stigma

The sticky receptive surface of the carpel upon which pollen grains land.

Style

The elongated neck or column of the carpel through which the pollen tube grows toward the ovary.

Ovary

The swollen base of the carpel that contains ovules and develops into a fruit following fertilization.

Ovule

A structure inside the plant ovary that contains the female reproductive tissues and matures into a seed after fertilization.

Stamen

The male reproductive organ of a flower (androecium), composed of an anther and a filament.

Anther

The terminal sac of a stamen containing microsporangia that produce microspores and pollen grains.

Filament

The slender stalk of the stamen that physically supports the anther.

Perfect flower

An individual flower that contains both male reproductive organs (stamens) and female reproductive organs (carpels).

Imperfect flower

An individual flower that possesses either stamens or carpels, but not both.

Embryo sac

The female gametophyte of angiosperms, organized into seven cells containing eight nuclei following three mitotic nuclear divisions.

Synergids

Two specialized cells flanking the egg cell in the angiosperm embryo sac that help guide sperm delivery from the pollen tube.

Antipodals

Three cells positioned at the opposite end of the embryo sac from the egg and synergids that often degenerate and may support nutrition.

Central cell

The large central cell of the angiosperm embryo sac containing two polar nuclei, which fuses with a sperm cell to form endosperm.

Micropyle

The tiny pore or opening in the ovule integuments through which the pollen tube enters the embryo sac.

Double fertilization

An angiosperm-specific mechanism where one sperm fuses with an egg to form a diploid ($2n$) zygote, and a second sperm fuses with two polar nuclei to form triploid ($3n$) endosperm.

Endosperm

A typically triploid ($3n$) nutritive tissue in angiosperm seeds created by the fusion of a haploid sperm with two polar nuclei to nourish the developing embryo.

Radicle

The embryonic root of a seed plant embryo.

Cotyledons

Embryonic seed leaves developed by the plant embryo within the seed.

Monocots

Angiosperms characterized by a single cotyledon, flower parts in multiples of 3, parallel leaf veins, fibrous roots, and scattered stem vascular bundles.

Eudicots

Angiosperms characterized by two cotyledons, flower parts in multiples of 4 or 5, networked leaf veins, taproots, ring-arranged stem vascular bundles, and representing roughly two-thirds of all