Ophioglossaceae

Ophioglossaceae 

a family of isosporous ferns of the order Ophioglossales. The plants are perennial herbs, many of which are epiphytes (in the tropics). The rhizomes are usually short, and the roots have a mycorrhiza and lack hairs. Unlike other ferns, the leaves are not spirally coiled. They develop very slowly and are divided into two parts that differ greatly in shape and function. The spore-bearing part is fertile, and the vegetative part is sterile. The spore-bearing segments, which are pinnately branched, are panicled or spicate. The sporangia are large, reaching 3 mm in diameter, and have massive, multilayered walls and a large number of spores. The fleshy prothallia (gameto-phytes) have a mycorrhiza and are sometimes densely covered with rhizoids.

There are four genera, embracing 70 to 80 species. The most common genera are Botrychium and Ophioglossum: the first is found mainly in the northern part of the temperate zone, and the second occurs mainly in the tropics. One species of the genus Helminthostachys is found in tropical forests of the Old World, and one species of the genus Rhizoglossum is distributed in southern Africa. An ancient, primitive group of plants, the Ophioglossaceae are descendants of Paleozoic ferns.

REFERENCE

Clausen, R. T. A Monograph of the Ophioglossaceae. Menasha, Wis., 1938. (Memoirs of The Torrey Botanical Club, vol. 19, no. 2.)

M. E. KIRPICHNIKOV