121 



crassi IS 20 mm. longi; fructus biennis solitarius ve\ geminatus 

 su bscssi lis; cupula parvatenuissima ;glans acute avoideapuber- 

 ula, 10 mm. crassa 18 mm. longa, tantum basi inclusa. 



Quercus gracilifonnis exhibits definite alliance with the Acut- 

 ifoliae of Northeastern Mexico. It differs from Quercus Canbyi 

 Trel. in having biennial fruit with acorns enclosed only at the 

 base and leaves with more numerous lobes. A part of the mater- 

 ial referred to var. parvilobata, however, can be distinguished 

 from Quercus Canbyi only by the fruit. Quercus graciliformis 

 differs from Quercus texana var. chisosensis, to which it has 

 been erroneously referred, in the characters of the section Acuti- 

 foliae to which it belongs. 



Quercus graciliformis .Mueller, sp. nov. Twigs very slender 

 (1.5 mm. or less), fluted, quickly glabrate, deep glossy red to 

 brown, grey in the second year, few small buff lenticels hardly 

 evident; buds small (1 x 1.5 to 1.5 x 2 mm.), ovoid glossy 

 brown, the scales ciliate; leaves deciduous, narrowly lanceolate, 

 long attenuate, cuneate at the base, setaceously 8 to 10-toothed 

 with somewhat deep rounded sinuses (rarely very shallow), 

 often unequally lobed, moderately small (2.5 x 8 or sometimes 

 3 x 8 or 2 x 10 cm.), soon glabrate, entirely smooth or very 

 rarely an axillary tuft beneath, glossy green above, more dull 

 beneath; veins fine, often branching but rarely looped, scarcely 

 raised above, more prominent beneath, usually passing alter- 

 nately into the teeth; petiole glabrous, deep red at the base 

 shading into straw color, dorsally flattened, very slender (0.5 x 

 15 to 20 mm.), soft flexible; catkins ?; fruit biennial, solitary or 

 sometimes paired, subsessile; cup small (scarcely 10 mm. in 

 diameter), shallow about 3 mm. deep); scales thin, appressed, 

 narrowly rounded at the apex, light brown, ciliate, white 

 pubescent along the mid-dorsal area; acorn acutely ovoid, about 

 10 x 18 mm. at maturity, finely dense pubescent, with longitu- 

 dinal dark markings, enclosed only at the base. 



A small tree 6 to 8 m. high with long, slender, flexible 

 branches and grey, furrowed bark, the trunk rarely over 0.3 m. 

 in diameter. 



The type (Mueller no. 565) was collected August 25, 1933 

 in Blue Creek Canyon in the Chisos Mountains at an altitude 

 of about 5500 feet and is deposited in the herbarium of the Uni- 

 versity of Texas at Austin. 



