pteridophytes

Pteridophytes are a group of vascular, seedless land plants that reproduce by spores. The clade includes ferns, horsetails, and lycophytes, which encompass clubmosses, spikemosses, and quillworts. They are among the earliest diverging lineages of vascular plants and lie outside seed plants and bryophytes.

They possess true vascular tissue, including xylem and phloem, and typically have roots, stems, and flat or finely divided leaves. Ferns usually have large fronds; lycophytes have microphyll leaves; horsetails display jointed stems with reduced leaves. In pteridophytes the sporophyte is usually the dominant life stage, while the gametophyte is typically small and short-lived.

Reproduction is by spores produced in sporangia. In ferns, sporangia are often grouped in sori on the undersides of fronds; in horsetails they appear in cone-like strobili; lycophytes bear sporangia on sporophylls that can be arranged in club-like strobili. Most pteridophytes are homosporous, but some lycophytes and other lineages are heterosporous, producing two sizes of spores.

Diversity and distribution: pteridophytes are diverse and have a rich fossil record, especially in the Paleozoic era. Today they occur worldwide, thriving in moist, shaded habitats and in tropical and subtropical regions. Some species are epiphytic or aquatic, while others are terrestrial.

Ecological and economic significance: pteridophytes contribute to forest ecosystems by forming understory cover, aiding soil formation and nutrient cycling, and supporting moisture and microhabitat diversity. They are also cultivated as ornamental plants and studied for insights into early land plant evolution.