Blechnum

Blechnum is a genus of ferns in the family Blechnaceae, commonly known as hard ferns. These ferns are found worldwide, with a particularly high concentration of species in the Southern Hemisphere.

Blechnum ferns exhibit a variety of growth habits, ranging from small, ground-dwelling plants to larger, more robust specimens. A characteristic feature of many Blechnum species is the presence of distinct fertile and sterile fronds. Sterile fronds are typically broader and responsible for photosynthesis, while fertile fronds are narrower and bear the sori (spore-producing structures).

The sori in Blechnum are linear and are located along the midrib of the pinnae (leaflets) on the underside of the fertile fronds. They are protected by a linear indusium, a flap of tissue that covers the developing spores. The arrangement of the sori and indusium is a key diagnostic feature for identifying Blechnum species.

Blechnum ferns are often found in moist habitats, such as rainforests, woodlands, and along stream banks. Some species are also adapted to more open, exposed conditions. They can be terrestrial, growing in soil, or epiphytic, growing on other plants.

The genus Blechnum includes a number of popular ornamental ferns cultivated for their attractive foliage. Some species are also used in traditional medicine in certain cultures.