142 CONTRIBUTIONS FROM THE NATIONAL, HERBARIUM. 



Agave paucifolia Tod. (Hort. Bot. Panorni. 1: 77. pi. J9. 1877) differs scarcely 

 more than in its fewer leaves, tliese as wide as in tlie next species. 



168. Agave echinoides Jacobi, Abh. Schles. Ges. Vaterl. Cult. 1868: 163. 1868. 

 Agatfe striata echinoides Baker. Gard. Chron. n. ser. 8: 556. 1877. 



Ilegion ? ; type cultivated in Europe. 



Leaves numerous, straight or slightly falcate, gray-green, rhombically bicon- 

 vex, 1 cm. wide, 25 to 30 cm. long, slightly scabrid on the margin, the surface 

 with clo.se narrow ribs, the triangular spine 3 mm. wide and 25. mm. long; 

 ovary slender, not protruding into the tube. 



169. Agave stricta Salra-Dyck, Bonplandia 7: 94. 1859. 

 Agave hystnx Gels, Cat. 1861: 19. 1861. 



Agave sti-iata stricta Baker, Gard. Chron. n. ser. 8: 556. 1877. 



Puebla, common about Tehuacfin ; type cultivated in Europe. 



Often densely cespitose; leaves numerous, falcately upcurved, often in a 

 globose cluster, gray-green or purplish to nearly white, triquetrously biconvex, 

 6 to 10 mm. wide, 25 to 35 cm. long, at most slightly scabrid. the surface with 

 distinctly separated ribs, the red-brown or fading spine 3 to 4 mm. wide and 25 

 mm. long ; ovary slender, scarcely protruding into the tube. 



The purplish formes known in gardens as f. purpurea; the rosy form, as f. 

 rosea; and the most glaucous form as var. glauca (or Agave or Littaea deal- 

 bata), of which there is a dwarf er form, f. nana. 



170. Agave falcata Engelm. Trans. Acad. St. Louis 3: 304, 370. 1875. 

 Agave calif ornica Baker, Gard. Chron. n. ser. 8: 556. 1877. 



Coahuila (type locality, Buenavista), Durango, Zacatecas, and Nuevo Le6n. 



Leaves rather numerous spi'eading, often falcate, gray or purplish, evanes- 

 cently glaucous, from biconvex or half-round becoming 3-sided. 7 to 15 mm. wide, 

 15 or commonly 30 to 50 cm. long, finely striate-ridged, the margin minutely 

 denticulate, the triquetrously needle-shaped spine 2 to 3 mm. wide. 15 or 35 to 

 40 mm. long. 



" Guapilla," " palmita," " espadin," " soyate," " sotolito " ; furnishing " ixtle " 

 or " Tampico fiber." 



13. DIOSCOREACEAE. Yam Family. 



1. DIOSCOREA L. Sp. PI. 1032. 1753. 

 Reference: Uline, Bot. Jahrb. Engler 22: 421-431. 1896. 

 Seandent plants, usually with large fleshy roots ; leaves mostly broad and 

 cordate, palmatoly 3 to many-nerved and reticulate-veined, entire or lobed ; 

 flowers small, usually dioecious, racemose or spicate ; fruit a 3-valved capsule. 



It is difficult to determine which, if any, of the species should be included 

 in the present treatment. Some of them certainly have large, more or less 

 persistent stems, but this character is rarely shown in herbarium specimens. 

 The writer has included most of the larger plants, although probably most of 

 them .should have been omitted. There have been excluded a number of species 

 which are evidently wholly herbaceous. 



Stems winged 1. D. alata. 



Stems not winged. 

 Leaves conspicuously lobed. 



Uppermost leaves conspicuously lobate 2. D. lobata. 



Uppermost leaves entire - 5. D. convolvulacea. 



Leaves entire. 



Staminate flowers solitary along the rachis of the raceme. 

 Starainate flowers 3 nun. long or larger. 



