Plant Diversity, Life Cycles, and Key Evolutionary Adaptations

Vocabulary flashcards covering the life cycles, reproductive structures, lineages, and major evolutionary adaptations of non-vascular plants, seedless vascular plants, and seed plants.

Sporophyte

The multicellular diploid ($2N$) generation in plants that possesses a sporangium and produces haploid ($N$) spores via meiosis.

Gametophyte

The multicellular haploid ($N$) generation in plants that produces haploid gametes via mitosis within gametangia.

Sporangium

A multicellular organ on a sporophyte where haploid ($N$) spores are produced via meiosis.

Spore

A haploid ($N$) reproductive unit produced by a sporangium that germinates and develops into a multicellular gametophyte.

Gametangia

Multicellular reproductive organs of plants, analogous to gonads, where gametes are produced and protected.

Antheridium

The male gametangium that produces and protects sperm cells.

Archegonium

The female gametangium that produces, protects, and retains egg cells, and houses the developing embryo.

Embryophytes

Land plants characterized by retaining a multicellular, dependent embryo within the archegonium, where it is nourished and protected by the female gametophyte.

Alternation of Generations

A plant life cycle pattern characterized by an alternation between a multicellular diploid adult stage (sporophyte) and a multicellular haploid adult stage (gametophyte) every generation.

Lycophytes

A lineage of seedless vascular plants that includes club mosses.

Monilophytes

A lineage of seedless vascular plants that includes ferns and horsetails.

Xylem

Vascular tissue specialized for transporting water and dissolved nutrients throughout the plant.

Phloem

Vascular tissue specialized for transporting sugars and hormones throughout the plant.

Sporophyll

A modified 'spore-leaf' on a sporophyte that localizes sporangia for more targeted release of spores.

Dominant Generation (Seedless Vascular Plants)

The sporophyte ($2n$) stage, which is the largest, most conspicuous, and longest-lasting form in the life cycle.

Heterospory

The production of two distinct types of sporangia by seed plant sporophytes: megasporangia and microsporangia.

Megasporangium

A sporangium found in seed plants that produces megaspores, which develop into female gametophytes.

Microsporangium

A sporangium found in seed plants that produces microspores, which develop into male gametophytes.

Ovule

A diploid ($2N$) protective structure surrounding the megasporangium that houses the megaspore and female gametophyte, and hardens into the seed coat.

Pollen Grain

A tiny male gametophyte (consisting of two cells) encased by sporopollenin that disperses through the air and produces sperm upon reaching a female gametophyte.

Seed

A structure containing three distinct generations: a diploid embryonic sporophyte, nutrient tissue from the female gametophyte, and a protective seed coat derived from the maternal sporophyte's ovule.