Pteridophytes

Pteridophytes

Seedless vascular plants with true roots, stems, and leaves that reproduce by spores.

Position in plant evolution

Intermediate group between bryophytes and seed plants.

Key innovation of pteridophytes

Development of vascular tissue allowing upright growth and efficient transport.

Vascular tissue

Xylem and phloem tissues that transport water, minerals, and food.

Xylem

Conducts water and minerals upward from roots.

Phloem

Transports organic food materials throughout the plant.

Dominant generation in pteridophytes

Sporophyte is dominant and independent.

Sporophyte

Diploid generation producing spores.

Gametophyte

Haploid generation producing gametes; small and reduced in pteridophytes.

Reproductive unit

Spores produced in sporangia.

Sporangium

Structure that produces and releases spores.

Spores

Haploid reproductive cells that develop into gametophytes.

Fertilization requirement

Requires water due to flagellated sperm.

Habitat preference

Moist and shaded environments due to water-dependent fertilization.

Roots in pteridophytes

True roots present for anchorage and absorption.

Stem in pteridophytes

True stem with vascular tissue for support and transport.

Leaves in pteridophytes

True leaves classified as microphylls or megaphylls.

Microphyll

Small leaf with a single unbranched vein.

Megaphyll

Large leaf with branched vascular veins.

Evolutionary importance of leaves

Increased photosynthetic surface and energy production.

Two main phyla of pteridophytes

Lycophyta and Pterophyta.

Lycophyta

Pteridophytes with microphylls including club mosses and spike mosses.

Members of Lycophyta

Lycopodium, Selaginella, Isoetes.

Geological origin of Lycophyta

Silurian period.

Pterophyta

Pteridophytes with megaphylls including ferns and their relatives.

Members of Pterophyta

True ferns, horsetails, whisk ferns.

Geological origin of Pterophyta

Devonian period.

True ferns

Pterophytes with large megaphyllous leaves called fronds.

Fronds

Large, divided leaves of ferns.

Sori

Clusters of sporangia found on underside of fern fronds.

Homosporous pteridophytes

Produce one type of spore.

Heterosporous pteridophytes

Produce two types of spores: microspores and megaspores.

Microspore

Develops into male gametophyte.

Megaspore

Develops into female gametophyte.

Evolutionary significance of heterospory

Precursor to seed habit in higher plants.

Economic importance of pteridophytes

Used as ornamentals, soil binders, and bioindicators.