Hymenophyllum axillare Sw., J. Bot. (Schrader)

Kessler, Michael & Smith, Alan R., 2017, Prodromus of a fern flora for Bolivia. X. Hymenophyllaceae, Phytotaxa 328 (3), pp. 201-226 : 209

Hymenophyllum axillare Sw., J. Bot. (Schrader) 180(2): 101. 1801.

= Hymenophyllum multiflorum Rosenst., Meded. Rijks-Herb. 19: 3. 1913.

= Hymenophyllum myriocarpum Hook., Sp. Fil. 1: 106, t. 37d. 1844.

= Hymenophyllum nigrescens Liebm. var. gracile Rosenst., Meded. Rijks-Herb. 19: 4. 1913.

= Hymenophyllum nigrescens Liebm., Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd. , ser. 5, 1: 292. 1849.

Range: —Greater Antiles; southern Mexico to Venezuela and Bolivia ( CH, CO, LP, SC).

Ecology: —Very common; epiphytic and rarely saxicolous or terrestrial in humid forests, grows from the lower tree trunks to the outer canopy; (1300–) 2000–4000 m.

Notes: —Specimens with pinnae ascending from the rachis (vs. spreading at right angles and often with deflexed pinnules) are often separated as H. myriocarpum , but this difference seems mainly to be related to water availability. Specimens with ovate to lanceolate (vs. elliptic to oblanceolate) blade outline, broadest near the base (vs. at or beyond the middle), and at most 1–2 (vs. many) reduced proximal pinnae have been called Hymenophyllum myriocarpum var. endiviifolium (Desv.) Stolze , but we see a continuum in leaf shapes. The taxonomy of H. axillare and its allies needs detailed study; see Lellinger (1991) for comments on the relationship between H. axillare and H. myriocarpum .

Hymenophyllum brevistipes Liebm., Kongel. Dansk. Vidensk. Selsk. Skr., Naturvidensk. Math. Afd. , ser. 5, 1: 290 [Mex. Bregn.]. 1849.

= Hymenophyllum dendritis Rosenst., Repert. Spec. Nov. Regni Veg. 6: 308. 1909.

Range: —The range is uncertain due to the complex and unresolved taxonomy of this species group, but this species has been attributed a wide range, from Mexico to Panama, Greater Antilles, and Colombia to Venezuela, Ecuador, Bolivia (BE, CO, LP, PA, SC), and Brazil.

Ecology: —Fairly common; epiphytic in humid forests, often in the canopy; 250–1550 m.

Notes: —The species complex involving Hymenophyllum abruptum Hook. , H. apiculatum , H. brevifrons Kunze , H. brevistipes , H. dendritis Rosenst. , H. siliquosum Christ , and H. tablaziense Christ , all relatively small species, is in need of monographic study. Hymenophyllym brevistipes differs from H. apiculatum by having smaller involucres that are broadest below the middle, and often laterally winged. Involucres are relatively large (0.8–1.3 mm long) and located both at the segment tips and bases.