FIG. 33.8 Lycophyte diversity. Living lycophytes include about 1200 species, in three major groups: (a) Lycopodium annotinum, showing yellow sporangia-bearing leaves at the shoot tips of this 5-to-30-cm tall plant; (b) Selaginella wildenowii, in a close-up showing the flattened arrangement of its 3-mm-long leaves; and (c) Isoetes lacustris, an aquatic lycophyte that grows from 8 to 20 cm tall.

Photo sources: a. Philippe Clement/Nature Picture Library; b. blickwinkel/Alamy; c. Biopix: JC Schou.