Alsophila jimeneziana D. S. Conant

Cyathea crassa Maxon, Contr. U. S. Nat. Herb. 13 : 40. 1909
Caudex erect, 3-8 meters high, spiny ; stipe undescribed ; rachis (at least in the upper part) castaneous, polished, glabrous ; pinnae dark-green above, paler below, coriaceous, deltoid-lanceolate, 40-60 cm. long, 15-22 cm. broad, sessile, with about 16-20 pairs of pinnules below the abruptly acuminate apex, the secondary rachis brownish-castaneous, glabrous and shining on the under surface, above deeply sulcate, minutely dark-pilose, and with a few scattering minute castaneous stellate scales ; pinnules contiguous or slightly apart, oblong to deltoid-oblong, 8-11.5 cm. long, 2^ cm. broad at the base, sessile or essentially so, cut nearly or quite to the costa, the apex long-acuminate, serrate-crenate ; segments 13-17 pairs, approximate or slightly apart, oblong, subfalcate, slightly oblique, obtuse, mostly adnate, the middle and lower ones decurrent, only the basal ones sessile, these the largest (up to 2 cm. long and 8 mm. broad), deeply inciso-pinnati-ftd (the lobes pinnately veined, sometimes with 2 basal sori), those above deeply inciso-crenate, the uppermost dentate-serrate ; costae, costules, veins, and surfaces glabrous below ; veins (excepting those of the basal segments) 1-3-forked, 6-8 pairs, mostly fertile ; sori near the costule, large, distant ; indusium castaneous, deeply hemispheric, rigidly coriaceous, persistent ; receptacle capitate, somewhat hirsute, glabrescent, slightly included.
Type locality : Forests of Mount Izabel de la Torre, Santo Domingo, altitude 550 meters. Distribution : Known only from the type locality.

Alsophila jimeneziana, synonym Cyathea crassa, is a species of tree fern endemic to the Dominican Republic. Little is known about this rare tree fern.

A. jimeneziana is part of the Alsophila woodwardioides complex from the Greater Antilles, together with five other species: Alsophila fulgens, Alsophila grevilleana, Alsophila portoricensis, and Alsophila tussacii (all also placed in Cyathea).

This species is not conspecific with Alsophila crassa Karsten, which is based on material collected from wet, cold, montane forest at Mérida by Franz Engel in 1859. The Checklist of Ferns and Lycophytes of the World considers it to be a synonym of Cyathea clandestina. Because the specific epithet crassa is unavailable for this tree fern if placed in the genus Alsophila, having already been used by Karsten, David Conant published the replacement name Alsophila jimeneziana in 1983.