Bio 108 topic 15 seedless vascular plants

Bryophytes

Non-vascular plants that dominated terrestrial vegetation for the first 100 million years of plant evolution.

Aglaophyton

An early vascular plant that exhibited anatomical features intermediate between bryophytes and fully developed vascular plants.

Xylem

Vascular tissue that conducts water and minerals via dead, hollow cells providing structural support.

Phloem

Living vascular tissue that distributes nutrients and organic products throughout the plant.

Sporophyte

The diploid phase of vascular plants that is dominant in size, complexity, and longevity.

Gametophyte

The haploid phase of mosses and some vascular plants, generally less complex than sporophytes.

Microphylls

Small leaves with a single vein that possibly evolved from outgrowths of stems.

Megaphylls

Large leaves with highly branched vascular systems that likely evolved from webbing between flattened branches.

Sporophylls

Modified leaves that bear sporangia, which are spore-producing organs.

Homosporous

The condition of producing a single type of spore that develops into a bisexual gametophyte.

Heterosporous

Producing two different types of spores: megaspores that develop into female gametophytes and microspores that develop into male gametophytes.

Flagellated sperm

Sperm that possess flagella and require water for fertilization.

Sori

Clusters of sporangia found on the undersides of sporophylls, typically in ferns.

Strobili

Cone-like structures formed from groups of sporophylls, typical in lycophytes and most gymnosperms.

Carboniferous period

A period during which ancestors of extant lycophytes, horsetails, and ferns dominated, leading to the formation of early forests.

Spores

Reproductive units produced by sporangia, capable of developing into new gametophytes.

Sporopollenin

A tough substance found in the walls of spores that protects them from damage.