40 MISC. PUBLICATION 47 7, U. S. DEPT. OF AGRICULTURE 



elliptic to lanceolate or oblong, entire to few- or several-toothed, the 

 veins not prominent, petioles short, glabrate and pruinose or per- 

 sistently tomentose; fruit long- or usually short-pedunculate, rather 

 small, the scales rather blunt, mostly brown-tipped and canescent. 



Range: Mexico, Coahuila to Chiapas. 



Includes: Q. sebifera Trel. and several Mexican species of which 

 Q. opaca Trel. is the type. 



18. Quercus sebifera Trel., Mem. Nat. Acad. Sci. 20: 93. pi 149. 

 1924. 



Quercus sebifera f. comitanensis Trel., Mem. Nat. Acad. Sci. 20: 

 93. pi. 149. 1924. 



Probably a shrub or small tree. Twigs 1 to 2 mm. thick, fluted, 

 from bufT-tomentose becoming glabrate or for a time somewhat pubes- 

 cent, becoming gray with scarcely evident lentieels. Buds 2 mm. in di- 

 ameter, rounded, glossy brown, glabrate; the stipules persistent, 3 to 4 

 mm. long, subulate. Leaves persistent for 2 or 3 seasons, thick and hard, 

 2 to 6 cm. long, 1 to 3 cm. broad, oblong to elliptic, often broadest 

 above the middle, apically rounded to subacute, basally cordulate or 

 rounded, undulately few-toothed toward the apex or merely mucronate 

 or entire, margins minute- or crisped-revolute, upper surface glossy, 

 from bufT-tomentose soon glabrate, lower surface similarly glabrate but 

 dully waxy-glaucous; veins 6 to 9 on each side, very irregular, much 

 branched and anastomosing toward the margin, scarcely evident 

 above and only slightly raised beneath ; petioles 1 to 6 mm. long, either 

 glabrate or persistently tomentose. Staminate catkins 2 to 5 cm. 

 long, rusty-tomentose, rather loosely flowered, the glabrous anthers 

 scarcely exserted from the pilose perianth. Fruit annual, clustered 

 distally on a peduncle 2 to 5 cm. long; cups 10 to 13 mm. broad, 

 shallowly goblet-shaped, the scales ovate and rounded or deltoid and 

 obtuse, obviously thickened basally, the apices closely appressed, 

 puberulent especially toward the base; acorns? (See pi. 50.) 



Range: Known only from Chiapas, Mexico (1,620 m.). 



Quercus sebifera is related to several other Mexican species of the 

 series Opacae, but it has no relatives in the Central American flora. 

 Its small hard leaves, waxy-glaucous beneath with scarcely prominent 

 veins, and its small cups clearly distinguish it from other species within 

 this area. The f . comitanensis cannot be held distinct. Its leaves are 

 minutely revolute as in the type, but the lack of coarse teeth (an 

 ephemeral character) explains the failure of the margins to become 

 crisped or falsely revolute. 



Specimens examined: 



MEXICO.— Chiapas: Comitan. June 6. 1906. Cook 79 (US [4] [type as sheet 

 no. 860265]: June 14. 1906, Cook 78 (US [type of f. comitanensis]). 



Series Virentes Trel., Mem. Xat. Acad. Sci. 20: 112. 1924. 



Medium-sized or large trees or exceptionally shrubs with the twigs 

 closely tomentose; leaves evergreen, rather small, entire or sometimes 

 repandly or acutely few-toothed, glabrous above and minutely ap- 

 pressed-canescent beneath; veins inconspicuous or somewhat impressed 

 above, only the principal ones raised beneath; fruit annual, pedun- 

 culate, with thin or keeled appressed scales. 



