46 CONTRIBUTIONS FROM THE NATIONAL, HERBARIUM. 



8. Alsophila scabriuscula Maxon, Proc. Biol. Soc. Washington 32: 125. 1919. 

 Region of Cordoba, Veracruz, Also in Alta Verapaz, Guatemala, the type 



from Cubilquitz, altitude 350 meters. 



Oaudex arborescent, presumably stout and several meters high ; fronds very 

 ample, the stout stipe bearing numerous slender conical spines about 4 mm. 

 long; blades ample, the primary rachis sparsely aculeate toward the base, hir- 

 sute, scabrous from the persistent bases of the pale spreading septate hairs; 

 pinnae narrowly oblong, acuminate, 50 to 75 cm. long, 18 to 30 cm. broad, 

 the secondary rachis hirsute, scabrous with age ; pinnules approximate, spread- 

 ing, sessile, oblong-linear, long-acuminate; segments herbaceous, deeply incised, 

 the lobes usually bidentate; costules and veins sparsely hirsute beneath and 

 with a thin covering of minute, closely appressed, septate hairs. 



9. Alsophila bicrenata (Liebni.) Fourn. Mex. PI. Crypt. 134. 1872. 

 Cyathea bicrenata Liebm. Dansk. Vid. Selsk. Skrivt. V. 1: 289. 1849. 

 Mountains of Veracruz, Puebla, Oaxaca, and Chiapas, at 1,200 to 2,100 



meters elevation, the type from Puebla. 



Caudex 5 to 10 meters high, up to 15 cm. thick ; stipe short, yellowish brown, 

 short-aculeate ; blades 2 to 4 meters long, elongate-lanceolate, the primary rachis 

 sparingly hirsute with gland-tipped, laxly unciform, septate hairs, scabrous 

 from their persistent inflated bases ; pinnae oblong-lanceolate, acuminate, 45 to 

 60 cm. long, 14 to 20 cm. broad ; pinnules 25 to 30 pairs, linear, attenuate. 10 to 

 15 mm. broad, sessile ; segments narrowly oblong, subfalcate, herbaceous, 

 deeply crenate-serrate, the teeth bidentate. 



4. DICKSONIA L'Her. Sert. Angl. 30. 1788. 



REFEatENCE: Maxon, The North American tree ferns of the genus Dicksonia, 

 Contr. U. S. Nat. Herb. 17: 1.53-156. 1913. 



Caudex erect, 1 to 10 meters high or more, stout, often with a thick growth 

 of adventitious roots toward the base, greatly thickened above by the long- 

 persistent stipe bases of old fronds; fronds numerous, rigidly ascending in a 

 terminal crown, the short stout stipes and the summit of the caudex with a 

 copious covering of bright brown to ferruginous silky capillary scales, these 

 straight or matted, several cm. long, one cell broad ; lamina ovate to 

 oblanceolate, 2 to 3-pinnate ; pinnae mostly equilateral, the pinnules elongate ; 

 segments coriaceous or rigidly herbaceous, dimorphous or (in our species) 

 uniform ; veins simple or several times forked ; sori terminal ; indusium bival- 

 vate, the outer lip consisting of a deeply concave, rounded, greenish, scarcely 

 modified lobule of theii leaf margin, the inner lip dark or yellowish brown, 

 deeply concave, usually coriaceous and equaling the outer lip. 

 1. Dicksonia ghiesbreghtii Maxon, Contr. U. S. Nat. Herb. 17: 155. 1913. 



Temperate mountain region of Chiapas, the type collected by Ghiesbreght. 



Caudex 4 to 5 meters high; blades essentially tripinnate; primary pinnae 

 linear-oblong, acuminate, 60 to 70 cm. long, about 20 cm. broad, the rachis 

 slightly rough from the abrasion of the articulate, turgid, dirty yellow, capillary 

 scales ; pinnules numerous, contiguous, alternate, sessile, linear-oblong, long- 

 acuminate, the costa with a few capillary scales beneath ; segments 20 pairs 

 or more, linear-oblong, straight or subfalcate, 10 to 15 mm. long, the sterile ones 

 serrate to obliquely incised, the fertile ones pinnatifid two-thirds the distance 

 "to the elevated costule ; veins 7 or 8 pairs, those of the fertile segments usually 

 once forked ; sori mostly 4 or 5 pairs, 1 mm. broad. 



