Gametophytes of Botrychium lunarioides and their mucilage-coated rhizoids

Abstract

Gametophytes of Botrychium lunarioides grown in axenic culture are thickened, white, dorsiventral structures with antheridia and archegonia on the dorsal surface. The antheridia are on a raised median antheridial ridge and the archegonia form on the steep flanks of this ridge. Rhizoids, unicellular and bicellular, arise on the marginal and ventral surfaces of the gametophytes. Multicellular rhizoids are initiated on the antheridia. All rhizoids have a transparent mucilaginous sheath which may be of uniform diameter or beaded. Histochemical studies have shown the mucilage to be composed of an acid mucopolysaccharide with polyphenolic materials present. It is proposed that the rhizoid mucilage functions like the mucilage on the roots of seed plants.