Seedless Vascular Plants: Types and Characteristics

Sporophyll

Modified leaves with sporangia that produce spores.

Sporangium

Structure that produces spores.

Homosporous plants

Plants that produce bisexual gametophytes.

Sori

Clusters of sporangia found on the underside of the sporophylls in ferns.

Strobili

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

Seedless vascular plants

Plants that have flagellated sperm and are usually restricted to moist environments.

Rhizomes

Horizontal underground stems that help with nutrient absorption and plant spreading.

Lycophytes

The most primitive group of vascular plants.

Giant lycophytes

Thrived for millions of years in moist swamps.

Surviving Lycophytes species

Small herbaceous (non-woody) plants, including low-growing understory plants, epiphytes, and submerged aquatics.

Club mosses and spike mosses

Despite their names, they have vascular tissues, unlike true mosses.

Spike mosses

Grow horizontally.

Quillworts

Named for their leaves.

Club mosses

Usually evergreen.

Monilophytes

Have leaves called megaphylls.

Diversity of Monilophytes

They have more than 12,000 species and include large leaves called fronds.

Horsetails during Carboniferous period

Were diverse during the Carboniferous period but are now restricted to the genus Equisetum with about 15 species.

Horsetails' cell walls

Contain silica, making the stems coarse-textured.

Whisk ferns

Resemble ancestral vascular plants with virtually no leaves and no roots.

Ancestors of modern lycophytes, horsetails, and ferns

Grew to great heights, forming the first forests and increasing photosynthesis, which may have helped produce global cooling at the end of the Carboniferous period.

Decaying plants of Carboniferous forests

Eventually became coal.

Leaflets of ferns

Called pinnae (plural).