Bolbitis Schott

Rhizome creeping or low-climbing, unbranched or with accessory branches dorsally (and laterally), with 2-6 rows of fronds, ventrally (and laterally) with roots; scales ± appressed, pseudo-peltate, triangular from a perfoliate or subcordate base, up to 15 mm long, usually subclathrate, sometimes (in B. sinuata) ± opaque, with sparsely set, slender, uniseriate, thin-walled glandular hairs; vascular system dorsiventric, with a broad gutter-shaped ventral bündle and 1-3 (in B. heteroclita rarely up to 4) dorsal bundles (Fig. 25d). Fronds usually close together, in B. heteroclita sometimes spaced; petiole (long-) decurrent on the rhizome, near the lamina base with l(-3) median and on either side a lateral longitudinal ridge (Fig. 25e), aerophores linear, pale, present laterally on either side and especially conspicuous in the basal part of young fronds, in cross-section near the base with a ± U-shaped arrangement of 3-16 vascular bundles of which the two anterior ones are largest. Sterile fronds simple or (bi)pinnate with the pinnae alternate or ± opposite and usually continuous with the rachis, in some species ± subarticulate, the two lowermost pinnae usually conform to the other pinnae, sometimes deltoid, sessile or shortly petiolulate, usually herbaceous, sometimes coriaceous, with usually one, rarely more subterminal or terminal bulbils, surface when young apart from scales densely set with uniseriate glandular hairs; venation pattern: veins free (ser. Egenolfianae) or variously anastomosed and with or without included free veins in the areoles. Fertile fronds of similar shape as the sterile ones though with a proportionally larger petiole and a smaller lamina, usually completely acrostichoid, sometimes pteridoid or moniliform; spores with a thin exospore and a variously shaped perispore (Fig. 26a-c). Chromosomes n = 41, 82; 2n = 82, 123.

The species are all forest ferns; most of them grow in seasonally dry forest, others in everwet habitats. They mostly occur at low altitude, only a few species being sometimes found above 1500 m. The greater part of the species occur on rocks and especially in stream-beds, a naturally disturbed habitat. Some otherwise terrestrial species are sometimes also found as low-climbers (or as low-epiphytes). Some species are not rarely reported to form pure stands of many closely aggregated plants in forests (B. sinensis). Of B. heteroclita several forms occur which may cover (rocks of) stream-banks completely ( Holttum Ferns Malaya 1954 463 ), one of these being an autotriploid.