Pterophyta: ferns, horsetails and whisk ferns
Psilophytes (whisk ferns) are diminutive, dichotomously branched (Y branches), photosynthetic stems that reproduce sexually by aerial spores.
- Sphenophytes (horsetails) have green jointed stems with occasional clusters of leaves or branches. Their cell walls contain silica that give the stem a rough texture.
- Contain strobili which are clusters of sporangia that produce spores.
- Ferns are the most succesfull occupying deserts to tropical rain forests. They have rhizoids to anchor the plant.
- Contain sori which are clusters of sporangia and leaves called sporophylls.