Alsophila tussacii (Desv.) D. S. Conant

Cyathea tussacii Desv. Mem. Soc. Linn. Paris 6 : 323. 1827
Caudex 6-7 meters high, 10-15 cm. in diameter, rough, toward the crown very densely covered with sharp curved spines, the fronds deciduous (frequently all falling together seasonally), leaving large rough oval scars ; stipe very stout, 3 cm. or more thick at the base, 35-75 cm. long, curved, everywhere grayishfur f uraceous and densely armed with strong curved purplish-brown spines 6-9 mm. long, the inner side with numerous very narrow dark-brown scales ; lamina ample, 2.5 meters or less long, about 1.25 meters broad, slightly reduced at the base, tripinnate, coriaceous, dull-green above, gra3dsh-green beneath ; primary rachis yellowish-brown , tuberculate near the base, above muricate, finely furfuraceous, conspicuously fibrillose with slender striped tawny or grayish scales ; pinnae numerous, alternate or subopposite, approximate or their bases imbricate, sessile or short-stalked (only the lowermost long-stalked, up to 15 cm.), lanceolate, 60-70 cm. long, 18-24 cm. broad, slightly oblique, short-acuminate, the secondary rachis yellowish, furfuraceous, similarly fibrillose (especially at the base); pinnules about 35 pairs, approximate or slightly spaced, 8-11 cm. long, 1.7-2.3 cm. broad, at the base fully pinnate, nearly so throughout, tapering rather abruptly in the outer fourth to a serrate-acuminate apex, the costa pilose and densely paleaceous, the scales pale-olivaceous, lanceolate to ovate ; segments about 22-24 pairs, narrowly oblong, 9-11 mm. long, 3.5-4 mm. broad, close, slightly falcate, subacute, the margins entire, subrevolute, the costule clothed like the costa ; veins 11-13 pairs, mostly onceforked near the base ; sori 1-3 pairs, at the forking of the veins, close to the costule and obscuring it, basal on the segment; indusium deeply cyathiform, pale-brownish, membranous ; receptacle stout, setiferous, extruded with age.
Type locality : Jamaica.
Distribution : Known only from Jamaica, there common in damp forest ravines of the Blue mountains, at from 900 to above 1800 meters elevation.

Alsophila tussacii là một loài thực vật có mạch trong họ Cyatheaceae. Loài này được (Desv.) D.S. Conant mô tả khoa học đầu tiên năm 1983.