40 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



with even margins, or (2) globose, at first wholly inclosing the sporangia, 

 bursting irregularly at maturity, the divisions persistent or often disappearing. 

 Indusia saucer-shaped, never inclosing the sporangia, with low even margins, 



1. C. arborea. 

 Indusia at first globose and inclosing the sporangia, iit length rupturing, the 

 divisions persistent to fugacious. 

 Pinnules (secondary pinnae) distinctly petiolate, the lower ones with stalks 



4 to 9 mm. long; leaf tissue coriaceous 2. C. tuerckheimii 



Pinnules mostly sessile or nearly so, membranous or herbaceous. 



Rachises of the pinnae densely clothed with spreading or retrorse, linear, 

 spinulose scales, sharply muricate from their persistent bases ; pinnules 



cut to the costa nearly throughout 3. C. princeps. 



Rachises of the pinnae bearing a few deciduous scales, smooth or nearly so ; 

 pinnae very deeply pinnatifid, but the segments distinctly though nar- 

 rowly .joined. 

 Costae of the pinnules glabrous beneath ; leaf tissue bright green beneath ; 



sori large, apart from the costule 4. C. jurgensenii. 



Costae pilose or minutely squamulose beneath ; leaf tissue much paler 

 beneath than above ; sori small, borne near or against the costule. 

 Pinnae long-petiolate (4 cm. or more) ; pinnules about 20 pairs; seg- 

 ments obtuse; veins 6 to 8 pairs, glabrous 5. C. trejoi. 



Pinnae subsessile or short-petiolate ; pinnules 30 to 40 pairs ; segments 

 acute or acuminate ; veins 8 to 12 pairs, usually minutely glandu 

 lar-pubescent 6. C. mexicana 



1. Cyathea arborea (L.) J. E. Smith. Mem. Accad. Sci. Torino 5: 417. 1793. 

 Polypodium arboreum L. Sp. PI. 1092. 1753. 



Disphenia arborea Presl, Tent. Pter. 56. 1836. 



Hemitelia arborea F4e, Mem. Foug. 5: 350. 1852. 



Lowlands of eastern Mexico ; rare. Generally distributed and common in 

 the West Indies, the type from Martinique; variously reported from Central 

 America and northern South America, probably in error. 



Caudex erect, 4 to 12 meters high, usually with close-set, oval to broadly 

 subhexagonal scars in 8 to 10 ranks, the apex clothed with large, lance- 

 atteuuate, dirty white scales ; fronds 2.5 to 4 meters long ; stipes stout, pale, 

 low-tuberculate ; blades 2 to 3 meters long, ovate, tripinnate, the rachises pale, 

 glabrate; pinnae oblong, 40 to 80 cm. long, petiolate, or the shorter basal ones 

 ovate and long-petiolate ; pinnules numerous, mostly sessile, spreading, oblong- 

 lanceolate, long-attenuate ; segments linear-oblong, dilatate, sharply serrate, 

 often revolute, the costule invariably with 1 or 2 white bullate scales at the 

 base beneath ; veins 1 to 3-forked. 



This is one of the few species of Cyatheaceae which grow naturally in open 

 sunny situations. It occurs often in colonies. 



2. Cyathea tuerckheimii Maxon, Contr. U. S. Nat. Herb. 13: 4. 1909. 



Region of Orizalia, Veracruz, at an altitude of about 1,300 meters. Also 

 near Cobfiu, Alta Verapaz, Guatemala (the type locality), at 1,350 to 2,000 

 meters elevation. 



Caudex erect, 3 te 4 meters high ; fronds ample, at least 130 cm. broad, 

 bipinnate-pinnatifid, the stout primary rachis <ieciduously furfuraceous, 

 minutely spiny ; pinnae oblong-lanceolate, acuminate, up to 65 cm. long, the 

 rachis strongly muricate; pinnules 28 to 30 pairs, contiguous, short-petiolate, 

 oblong-lanceolate, attenuate, up to 13 cm. long, pinnately cut nearly to the 

 minutely and deciduously scaly costa ; segments about 22 pairs, 10 to 12 nnn. 

 long, oblong, falcate, subacute, coriaceous, the crenate-serrate margins revo- 



