394 TRANS. ST. LOUIS ACAD. SCIENCE. 



well distinguished by its tomentose young leaves and branchlets, which 

 latter retain this coating for several years. The full-grown leaves are 

 short-pedicelled, ovate- lanceolate acute, at base obtuse, undulate-crenate 

 (only on young shoots spinose-dentate), glabrous above and brownish- 

 furzv below, about 2 inches long and half as wide, and persist into the third 

 year. Male aments tomentose, calyx lobes oval-obtuse, anthers about 10. 

 cuspidate; female flowers short-peduncled. Large oval acorns (16 lines 

 long) in a shallow cup covered with dense brown wool, from which pro- 

 trude the small triangular tips of the scales. Maturation of the fruit un- 

 known, but, from the close affinity to chrysolefis, probably biennial, though 

 the apparently nearly allied ^>. tomentosa, Willd. has annual fructification. 

 ^. Emoryi, Torr. (see p. 382, where, 1. 3 from below, "Whipple" ought 

 to read Wheeler). This form, which connects the White-oaks with the 

 Black-oaks, is of the greatest interest to the student, but annoying enough 

 to the systematic botanist. While we have several other Black-oaks with 

 annual fructification, I know of only this one with basal abortive ovules, 

 like the White-oaks; but the black rough bark, the wood, the small num- 

 ber (2-5) of large anthers, the long, recurved styles, the membranaceous 

 brown cup scales, and the tomentose inner coating of the shell, can leave 

 no doubt about its proper position among the Black-oaks. It grows from 

 West Texas through New Mexico to Arizona, generally as a large bush, 

 but Dr. Palmer and the Rev. Mr. Greene have found it also a tree up to 

 2 feet diameter at base and 30 feet high. Its leaves are persistent through 

 winter, but fall about the flowering-time. 



J>. rubra, Lin., so easily recognized in its typical form, is really one of 

 the most variable of the Atlantic species, especially north and northwest- 

 wardly. All the forms have a smoothish bark with rather shallow fissures, 

 the young leaves lose their early thick down (usually pale below and bright 

 red above) at or soon after flowering-time, and the scales of the ordinarily 

 very shallow, large cups are small, closely appressed, and slightly downy 

 or almost glabrous. The lobes of the normal leaf taper almost undivided 

 from a broad base, bearing a few coarse or small teeth; but other forms 

 have leaves similar to those of coccinea, with divaricately pinnatifid lobes, 

 or the leaves are smaller and more deeply divided, with fewer lobes, much 

 like those of palustris: their acorns are always smaller than in the typical 

 rubra and the cup rather deeper. Var. runcinata has narrower, lobe- 

 dentate leaves, the large, regular teeth nearly entire. The acorns of rubra 

 are between 6 and 12, usually 9 or 10 lines thick, ovoid, rarely elongated 

 or sometimes subglobose. In northern forms the cup is apt to become 

 more hemispherical or even turbinate, and the scales not rarely tumid at 

 base after the manner of the White-oaks. This form I take to be^>. ambi- 

 gua, Michx., which by others is thought to be a variety of the next species- 

 Some oaks from Northern Illinois (Bebb, Nos. 4, 5 & 7). with rather larger 

 and looser cup scales, and, except 7, with deeply pinnatifid leaves, come 

 near to coccinea, and may possibly be hybrids of rubra and coccinea . 



^>. coccinea, Wang, is readily distinguished by its turbinate cups with 

 large, loosely imbricate (when dry almost squarrose), yellowish -gray 



