MEDICAL BOTANY - A.H. Serbin - 2003

SECTION 3. SYSTEMATICS

SUPERKINGDOM EUCARYOTA — EUCARYOTA. KINGDOM PLANTAE

SPORE-PRODUCING PLANTS

DIVISION PTERIDOPHYTA — PTEROPHYTA (POLYPODIOPHYTA)

The division comprises about 11,000 species. They are quite widely distributed in the tropics, temperate regions, and deserts, adapted to a variety of habitats, and represented by diverse life forms ranging from tree-like plants to tiny plantlets. The dominant generation is the sporophyte, which differs from other spore-producing plants by having large leaves (macrophylly). The leaves of ferns—which are homologs of modified cladode shoots—are called fronds. They combine the Functions of assimilation and spore production, and grow by means of an apex; in viviparous forms, brood buds are formed within the mesophyll. Young leaves are circinately coiled (fiddleheads). Strobili are absent; sporangia are gathered into sori ("clusters") on ordinary or sporogenous leaves, sometimes protected by a membrane, or indusium. Spores are homosporous or heterosporous. The reduced generation is the gametophyte. These are green terrestrial or chlorophyll-free subterranean, usually bisexual, thalloid prothalli with rhizoids. Archegonia are located on their upper, ventral side, while antheridia are scattered along the margins or in the lower part. Spermatozoids are multiflagellate.

According to the modern Classification, the division is subdivided into 7 classes, 3 of which are represented by extant ferns. The life cycle of ferns is shown in Fig. 2.43 (p. 110).

Class Polypodiopsida

Family Aspidiaceae

Male fern — Dryopterix filix-mas (Fig. 3.105) is distributed worldwide and prefers shady forests. It is a perennial herbaceous plant without aerial shoots, featuring a thick, ascending rhizome composed of an axis and remnants of leaf petioles covered with soft, brown scales. Adventitious roots are numerous and cord-like. A funnel-shaped tuft of large (1–1.5 m) petiolate, oblong-elliptic, bipinnately divided leaves is formed annually at the apex of the rhizome. First-order segments are linear-lanceolate and alternate. Second-order segments are oblong, with a blunt apex and a dentate-incised margin. In spring, on their lower side along the Veins, 2 to 4 pairs of sori with an indusium develop. Sporangia are long-stalked and dehisce via a mechanical annulus. Spores are homosporous, germinating into a bisexual gametophyte—a small (1.5–5 mm) green, Heart-shaped thallus. Following Fertilization, the new sporophyte develops on the prothallus and is nourished by it for some time.

Class="center">Fig. 3.105. Sporophyte of the male fern: A, B, C — rhizome: general view, diagram, dry crude drug; D — young leaves; E — mature fronds (general view, structural diagram, lower part fragment); 1 — primordial leaflets of the apical rhizome bud; 2 — petioles; 3 — axial part of the rhizome; 4 — adventitious roots; 5 — thickened bases of the fronds; 6 — membranous scales of the petiole; 7 — rachis; 8 — first-order segments (pinnae); 9 — second-order segments (pinnules); 10 — sori (general view, cross-section); 11 — sporangia; 12 — spores

The rhizome is poisonous! It is used with caution as an anthelmintic, analgesic, and wound-healing agent.