STANDLEY TREES AND SHRUBS OF MEXICO. 323 



Shrub or small tree, up to 6 meters high, the trunk sometimes 18 cm. in diam- 

 eter, the branchas stiff and croolced ; bark thin, reddish brown, scaly ; leaves 4 

 to 8 cm. long ; corymbs 5 to 8 cm. wide ; wood hard, close-grained, dark brown, 

 its si>eciiic gravity about 1.13. 



2. Vauquelinia australis Standi. Proc. Biol. Soc. Washington 31: 132. 1918. 

 Known only from the type locality, Cerro de Paxtle, Puebla. 



Leaves 3.5 to 6 cm. long, serrulate, lustrous on the upper surface; corymbs 

 about 4 cm. broad ; petals 3.5 mm. long. 



3. Vauquelinia corymbosa Correa ; Humb. & Bonpl. PI. Aequin. 1 : 140. 1808. 

 Vanquelwi-a angustifolia Rydb. N. Amer. Fl. 22: 260. 1908. 



Chihuahua and Coahuila to Hidalgo; type from Actopan, Hidalgo. Western 

 Texas. 



Tree, up to 10 meters high ; with brown bark ; leaves 5 to 10 cm. long or 

 larger, long-petiolate. " Guauyul," " guayule," " palo prieto," " arbol prieto," 

 ■" palo verde " (Durango, Patoni). 



The wood or bark is said to be used for dyeing goat skins yellow. Patoni 

 states that the name " guayule " belongs properly to this plant rather than to 

 Parthenlum argentatmn, to which it is now generally applied, and that iti is 

 doubtful how it came to be applied to the latter plant. V. angustifolia differs 

 from the typical form in having less salient teeth, but the two forms are con- 

 nected by specimens intermediate in character. 



4. Vauquelinia pauciflora Standi. Proc. Biol. Soc. Washington 31: 132. 1918. 

 Known only from the type locality, Guadalupe Canyon, northeastern Sonora. 

 Tree ; branches dark gray, leafy at the tips ; leaves lustrous on the upper 



surface. 



Rydberg has applied the name V. torreyi S. Wats, to this species, but that is 

 evidently only a new name for Spiraea califortvica Torr. It may be that F. 

 pauciflora is only a form of V. californica. 



5. Vauquelinia karwinskyi Maxim. Act. Hort. Petrop. 6: 236. 1879. 

 Vauquelinia potosina Painter; Standi. Proc. Biol. Soc. Washington 31: 131. 



1918. 

 San Luis Potosf and probably elsewhere ; type from Santiaguillo. 

 Shrub or small tree wath dark brown branches ; leaves long-petiolate, lustrous 

 -on the upper surface. 



6. Vauquelinia latifolia Rydb., sp. nov. 



Coahuila and Tamaulipas ; type from mountains near Miquihuana, Tamau- 

 lipas, altitude 2,100 to 2,700 meters. (Nelson 4481 ; U. S. Nat. Herb. no. 332669). 



Shrub, 1 to 2.5 meters high ; leaves petiolate, ovate to ovate-oblong, 5 to 6.5 

 cm. long, 2.5 to 3 cm. wide, obtuse or acute, rounded at base, coarsely serrate, 

 thick-coriaceous, glabrous, lustrous, often glaucescent beneath ; corymbs many- 

 flowered, dense, glabrous, 4 to 5 cm. broad, the flowers about 6 mm. long. 



4. SERICOTHECA Raf. Sylva Tell. 152. 1839. 

 Small or large shrubs ; leaves estipulate, dentate ; flowers small, white, pani- 

 culate, the panicles often large and showy ; petals 5 ; stamens about 20 ; fruit of 

 5 small follicles. 



Teeth of the leaves lanceolate or triangular-ovate, ending in a long mucro; 

 stamens shorter than the calyx lobes. 



Leaves glabrous on the upper surface 4. S. fissa. 



Leaves velvety-pubescent on the upper surface 5. S. velutina. 



Teeth of the leaves rounded or rounded-ovate, with a short mucro; stamens 

 usually equaling the calyx lobes. 



