108 JOURNAL OF THE ARNOLD ARBORETUM [vol. ii 



20-25, rarely 30-35 cm. at 30 cm. from ground. Not uncommon on lime- 

 stone cliffs, and on soils derived from the weathering of limestone along the 

 Pecos River near its junction with the Rio Grande in southwestern Texas 

 and along the Rio Grande near the mouth of the Pecos on both sides of the 

 river in Texas and in Coahuila, Mexico. It grows densely crowded in the 

 narrow ravines or vegas in the limestone near the mouth of the Pecos River. 



The young foliage of this species is wine-red in early spring. 



This new species, Pistacia iexanay differs from P. mexicana, HBK. in 

 having smaller leaves with fewer leaflets (4-9, usually 5-8 pairs, instead of 

 8-18, usually 12-16 pairs), which are more or less spatulate, broader and 

 more obtuse at the tip, not so markedly mucronate and more or less curved. 

 The young twigs ai'e much less pubescent and have smaller and less pubes- 

 cent flower-buds and bracts than in P. mexicana. The mature fruits of 



aucous 



and purplish black, as in P. mexicana. The trunks of the trees of P. texana 

 are much branched near the ground, while P. mexicana often (perhaps 

 always) has a single trunk. The smaller branches are rough grayish 



mexicana 



gray 



Type Lo 



the Pecos River, about 20 miles west of Comstock» Valverdc County. Texas. The 

 type specimens (type and nierotypes^) were collected by iS. C. Mason, March 18, 

 1911, from a pistillate tree marked III-XVII, M. 26, about two miles above Hino- 

 jose Spring. ^ The male syntypes were collected by S. C. i/o^or?, March 18, 1911, from 

 a tree growing on the bank of Ilinojose Spring. Both the female type and male 

 syntype are specimens In the National Herbarium and merotypes of both are in 

 the Arnold Arboretum herbarium. 



Numerous other collections (all in flower) made near the mouth of the Pecos m 

 Valverdc County, Texas, by F. B. Ueadley in March, 1907; and by Trof. S. C. Mason 

 in March and April, 1910, and again in March, 1911, are all paratypes ^ as are the 

 following specimens: National Herbarium, No. 19714. Mexican Boundary Survey, 

 labeled '"Rhus Schcidiana'' fruiting twigs; Columbia College [Torreyl Herbarium, 

 Mexican Boundary Survey ''No. 152, Rocky Ravines near the mouth of the Pecos. 

 Bvjelow,"' fruiting twig; N.Y. Botanical Garden Herbarium, Mexican Boundary 

 Survey No. 152, labeled 'Tistacia mexicana HBK., Rhus pteroioides;' fruiting twig; 

 National Herbarium No. 364672, E. N. Plank, "pear Shumla, Valverde County, 

 Texas. June G, 1895," sterile twig; National Herbarium, Vernon Bailey No. 480-g, 

 *'Rio Grande near Comstock, July 29, 1902,'* with nearly ripe fruit; ^Vrnold Arbore- 

 tum, S. S. II[asti7igs], No. 25, "On banks of Rio Grande near Comstock,'* April 9, 

 1910, flowering branches; Arnold Arboretum, E. N. Plank, "Caftons of the Pecos 

 River, Texas," 1899, leaves only; National Herbarium No. 19717. Dr. Edward 

 Palmer, "Coahuila, Mexico, 1880" fruits; Arnold .Vrboretum. Dr. Edward Palmer, 

 No. 196 (N^), Saltillo. Coahuila, Mex., July 1-8, 1880, fruiting branch; National 

 Herbarium No. 842129. C. A. Purpus No. 4888, "Sierra de la Paila, Coahuila," 

 Mex., Oct. 1910, fruiting branches; Arnold Arboretum, C. G. Pringle, No. 1930, 

 "Rhus Mexicana, Gray . . • Canyons of the Sierra Madrcnear Monterey," Nuevo 

 Leon, Mex., June, 1888, fruiting branch; National Herbarium. No. 19716, C. G. 

 PringU, No. 1930 as above; Arnold Arboretum, "Pistacia Mexicana HBK., Monte- 

 rey fNueVO Leon. Mex.l. Coll. C. S. Ramp.nf Anril fi 1Rft7 \xx'rx friiU;T.« K^or,^T,«^. 



^ Swingle. Walter T.. Types of Species in Botanical 

 864-7, (No. 962, June 6, 1913), 



