Cyathea J.Sm., Mém. Acad. Roy. Sci. (Turin)

Lehnert, Marcus & Kessler, Michael, 2018, Prodromus of a fern flora for Bolivia. XX. Cyatheaceae, Phytotaxa 334 (2), pp. 118-134 : 122

Cyathea J.Sm., Mém. Acad. Roy. Sci. (Turin) 5: 416. 1793.

= Cnemidaria C.Presl, Tent. Pterid. 56. 1836.

= Trichipteris [ Trichopteris ] C.Presl, Delic. Prag. 1: 172. 1822.

This genus has 265 species worldwide, mostly in the Neotropics except for eight species in eastern Australasia and the western Pacific Islands. Bolivia has 34 species, with one hybrid and one endemic species.

Cyathea is a diverse genus of plants with different appearances, defined by petiole scales with differentiated margins but lacking marginal setae; darker teeth may occur but these are clearly the endpoints of ± dichotomously branching lines of cells in the differentiated scale margin. Plants are mostly terrestrial with stout rhizomes, creeping, ascending or more commonly erect trunks; few species are climbers or epiphytes (not present in Bolivia). Fronds can vary from simply pinnate to 3-pinnate. Spore ornamentation is relatively homogeneous with perispore deposited in small rodlets (psilate to baculate) in various thickness on an either smooth or verrucate exospore, which is mostly finely porate; in some species groups, spores with three large equatorial pores occur.

Some morphologically definable clades had been recognized as separate genera, i.e. Cnemidaria C.Presl ( Tryon 1970) and Hymenophyllopsis K.I.Goebel ( Goebel 1929). Maintaining these clades as subgenera could be possible ( Christenhusz 2009) but the heterogeneity of the remaining clades in Cyathea makes a subgeneric division of the whole genus unfeasible. Exindusiate species of Cyathea had been previously treated as a separate genus Trichipteris (sometimes spelled Trichopteris ; Tryon 1970) but Lellinger (1987) refuted its distinctness before molecular data confirmed its artificiality ( Korall et al. 2007).

Many species of Cyathea show considerable morphological plasticity depending on their growth conditions, with plants explosed to the full sun having smaller and short-petioled leaves, thicker laminar texture, and often denser indumenta, whereas shade-growing individuals have large, long-petioled, thin and more glabrous leaves ( Arens 1997). Plants in open habitats also often grow faster and hence have petioles more widely spaced along the trunk ( Arens 2001). Accordingly, conspecific plants can look quite different, and identification must often be based on scale and indusium characters.

Most species of Cyathea bear foliar nectaries ( White & Turner 2012) that attract ants, which prey on other insects, thus reducing herbivory ( Koptur et al. 2013).