22- Seedless Vascular Plants

Phylum Rhinophyta

The oldest seedless vascular plants.

Monobiontic

Plants that have only one multicellular form.

Dibiontic

Plants that have multicellular form in both sporophyte and gametophyte generations.

Homospory

Production of one kind of spore, giving rise to gametophyte plants that produce both egg and sperm cells.

Heterospory

Production of two kinds of spores - microspores (male gametophytes) and megaspores (female gametophytes).

Rhyniophytes

Earliest fossils of vascular plants, characterized by homospory.

Zosterophyllophytes

Small bunched plants with cuticle, ordinary epidermal cells, and stomata on the upper portion of naked stems.

Microphyll Line of Evolution

Lycophytes represent a distinct line of evolution out of early land plants.

Megaphylls

Larger leaves with more than one vascular strand, found in ferns, horsetails, and seed plants.

Evolution of True Roots

Allowed lycophyte sporophytes to anchor firmly, absorb efficiently, and grow to tremendous size.

Club Mosses

Small plants with rhizomes and short erect branches, having true roots and microphyll leaves.

Megaphyll Line of Evolution

Euphyllophytes:The positioning of branches became more regular and controlled, resulting in sporophyll structures instead of leaves.

Polypodiophyta (Ferns)

Perennial and herbaceous plants found in almost any habitat, characterized by distinct leaf primordia and fiddlehead growth.

Sori

Clusters of sporangia where meiosis occurs in ferns.

Alternation of Generations

Ferns display alternation of generation with a dominant sporophyte generation and small gametophytes.

Key Differences between Ferns and Mosses

Ferns can live in drier places, have a highly developed vascular system with lignin-reinforced vessels, and have a larger and longer-lived sporophyte generation.