Plant Biology: Seed Development, Pollination, Reproduction, and Taxonomy

Flashcards covering plant reproduction, floral anatomy, seed dormancy, germination, fruit classification, pollination strategies, evolutionary transitions, and taxonomic distinctions.

Seed

A mature ovule containing the embryonic plant of the next generation along with nutrient reserves, enclosed within a protective coat.

Fruit

The mature, enlarged ovary of a flowering plant that encloses the seeds and functions in their protection and dispersal.

Imbibition

The initial uptake of water by a dry seed, which activates stored enzymes and triggers the germination process.

Germination

The beginning of growth of an embryo, starting with water uptake (imbibition) and marked by the appearance of the radicle and shoot from the seed.

Emergence

The stage of seedling development defined specifically by the appearance of the shoot above the soil surface.

Epigeal Germination

A pattern of seed germination and seedling emergence in which the cotyledons are pushed above the soil surface.

Hypogeal Germination

A pattern of seed germination and seedling emergence in which the cotyledons or storage structures remain beneath the soil surface.

Scutellum

A specialized, large cotyledon found in monocots and grasses (such as maize) that absorbs and transfers nutrients from the persistent endosperm to the embryo.

Coleoptile

A protective sheath in monocot embryos that covers the rudimentary shoot tip and pushes up through the soil during emergence.

Coleorhiza

A protective sheath in monocot embryos that surrounds the young embryonic root (radicle).

Stamen

The male reproductive unit of a flower, composed of a supporting filament and an anther where pollen is formed.

Carpel

The female reproductive unit of a flower, consisting of a basal ovary containing ovules, an elongated style, and a terminal stigma that receives pollen.

Double Fertilization

A reproductive process unique to angiosperms in which one sperm nucleus fertilizes the egg cell to form a diploid ($2n$) zygote, while the second sperm nucleus fuses with two polar nuclei to form a triploid ($3n$) endosperm nucleus.

Endosperm

A triploid ($3n$) tissue formed during double fertilization that serves as a nutrient reserve for the developing embryo and germinating seedling.

Nectar Guides

Visual markings on petals, often visible to insects only under ultraviolet light, that direct pollinators toward nectar-producing glands.

Complete Flower

A flower that contains all four standard floral organs: sepals, petals, stamens, and carpels.

Incomplete Flower

A flower that lacks one or more of the four primary floral organs (sepals, petals, stamens, or carpels).

Monoecious

Having separate male (staminate) and female (pistillate) flowers borne on the same individual plant.

Dioecious

Having male (staminate) and female (pistillate) flowers produced on entirely separate individual plants.

Heterostyly

A structural adaptation promoting cross-pollination in which a plant species produces different floral morphs with varying style and stamen lengths (e.g., thrums and pins).

Self-Incompatibility

A genetic mechanism based on S-genes that prevents self-fertilization by recognizing self-pollen and blocking its germination or pollen tube growth.

Parthenocarpy

The production and development of fruit without prior fertilization, resulting in seedless fruit.

Simple Fruit

A fruit that develops from a single carpel or several fused carpels of a single flower.

Aggregate Fruit

A fruit that develops from multiple separate carpels belonging to a single flower (e.g., raspberry).

Multiple Fruit

A fruit that develops from the combined carpels of many individual flowers clustered together in an inflorescence (e.g., pineapple).

Accessory Fruit

A fruit whose fleshy, edible structure develops largely from floral tissues other than the ovary, such as an enlarged receptacle or hypanthium.

Silique

A dry simple fruit characteristic of the mustard family (Brassicaceae) that consists of two fused carpels and is more than three times longer than wide.

Protoplast

A plant cell that has had its surrounding cell wall removed.

Cellulose

A structural polysaccharide that forms the primary component of plant cell walls, making up over $30\times10^{-2}$ (or $30$ percent) of all plant matter.

Plastids

A family of double-membrane organelles unique to plants—including chloroplasts, chromoplasts, and amyloplasts—that function in photosynthesis, pigment synthesis, and food storage.

Bryophytes

Small, non-vascular land plants (such as mosses, liverworts, and hornworts) that lack true vascular system structures and require water for spore-based reproduction.

Alternation of Generations

A plant life cycle pattern characterized by alternating multicellular haploid ($1n$) gametophyte and multicellular diploid ($2n$) sporophyte phases.

Sporophyte

The multicellular diploid ($2n$) phase in the plant life cycle that produces haploid ($1n$) spores through meiosis.

Gametophyte

The multicellular haploid ($1n$) phase in the plant life cycle that produces haploid ($1n$) gametes through mitosis.

Monocot

A class of angiosperms characterized by embryos with a single cotyledon, parallel leaf venation, scattered vascular bundles, fibrous roots, and floral organs in multiples of three.

Eudicot

A class of angiosperms characterized by embryos with two cotyledons, netlike leaf venation, vascular tissue arranged in a ring, taproot systems, and floral organs in multiples of four or five.

Serial Endosymbiosis

An evolutionary theory proposing that eukaryotic cells originated through a sequence of events where endosymbiotic oxygen-utilizing prokaryotes evolved into mitochondria, and photosynthetic prokaryotes evolved into plastids.