Trichomanes

Plants epiphytic or on rock. Stems long-creeping or short and erect, clothed in masses of dark brown hairs of 2 or more types, including multicellular gland-tipped hairs and elongate, sometimes branched and often multicellular, rhizoidlike hairs. Roots sparse or absent on creeping stems, numerous and wiry on erect stems. Leaves entire, lobed, or compound, 0.5–20 × 0.2–5 cm. Petiole short, wiry, often partially or wholly winged. Blade glabrous or with scattered, multicellular, gland-tipped hairs on veins; margins entire or minutely lobed, sometimes bearing dark stellate hairs (or orbicular scales, Trichomanes membranaceum). Soral involucres conic. Sporangia sessile, formed at base of exserted bristle and carried outward by intercalary growth of bristle base. Gametophytes persistent, entirely filamentous or with proximal filamentous net producing aerial blades with gemmiferous apices. Gametophyte gemmae uniseriate.

Distribution

Nearly worldwide, mostly tropical, a few temperate.

Discussion

Trichomanes occurs primarily in tropical lowland and montane rainforests, a few species occurring in continuously moist, deeply sheltered habitats in temperate latitudes. Species outside the flora display a wide range of morphologies and habits. Some are terrestrial, some attain considerably larger size, and some have dimorphic fertile and sterile leaves.

Filamentous gametophytes of Trichomanes can be distinguished from algae and from moss protonemata by their short cells with numerous discoid chloroplasts, by the presence of short, brown, unicellular rhizoids, and by their production of specialized gemmifer cells and gemmae.

Species ca. 320 (8 in the flora).

Selected References

Wessels Boer, J. G. 1962. The New World species of Trichomanes sect. Didymoglossum and Microgonium. Acta Bot. Neerl. 11: 277--330.

Farrar, D. R., J. C. Parks, and B. W. McAlpin. 1982. The fern genera Vittaria and Trichomanes in the northeastern United States. Rhodora 85: 83--92.

Lower Taxa

Trichomanes boschianum, Trichomanes holopterum, Trichomanes intricatum, Trichomanes krausii, Trichomanes lineolatum, Trichomanes membranaceum, Trichomanes petersii, Trichomanes punctatum

Key

1	Plants entirely filamentous; on rock in temperate uplands of e U.S.	Trichomanes intricatum
1	Leaves entire to irregularly palmately lobed with veins repeatedly forking from base to weakly pinnate.	> 4
2	Leaves 2-4 cm, bearing dark, large, branched hairs on margins between lobes.	Trichomanes krausii
2	Leaves 4-20 cm, without hairs on margins.	> 3
3	Leaves 1-2-pinnate-pinnatifid, widely spaced on long-creeping stems.	Trichomanes boschianum
3	Leaves pinnatifid, clustered on short erect stems.	Trichomanes holopterum
4	Leaf margins fringed with paired disclike scales.	Trichomanes membranaceum
4	Leaf margins fringed with dark stellate hairs.	> 5
5	Soral involucres 1 per leaf; involucral lips not dark-edged; venation weakly pinnate.	Trichomanes petersii
5	Soral involucres 1-6 per leaf; involucral lips dark-edged; veins repeatedly forking from base.	> 6
6	Leaves 5-10 cm; soral involucres flaring at mouth.	Trichomanes punctatum subsp. floridanum
6	Leaves 1-3 cm; soral involucres not flaring at mouth.	Trichomanes lineolatum