30 BULLETIN 179, XJ. S. DEPARTMENT OF AGEICULTUEE. 



The tree attains a maximum height of about 40 feet and occurs 

 singly or in groves, but never suckers or forms thickets. The bark 

 of the trunk exfoliates in platelike scales when young, later becoming 

 furrowed, while the larger branches retain the bark character of the 

 young trunk; the bark of the twigs at flowering is usually grayish, 

 that of the young growth in summer duU chestnut. 



Prunus raexicana occurs (fig. 1) in open woods in rich alluvial bot- 

 tom lands, on the upland prairie soils, and even in sandy loam, and 

 ranges from southwestern Kentucky and western Tennessee south- 

 westward through northwestern Louisiana to the vicinity of Lerios, 

 Coahuila, Mexico, the type locality, and central Nuevo Leon, where 

 scattered trees occur on the northern slope of the Sierra Madre at 

 about 3,000 feet elevation. Its range extends westward through the 

 extreme southern part of Missouri to central Oklahoma and central 

 Texas. 



Prunus mexicana varies somewhat, but not more so than may be 

 expected in a species of its range. Specimens from Feliciana Parish, 

 La., have the calyx tube entirely glabrous, except for a few longish 

 hairs toward the base, with pedicels 17 to 18 mm. long. The calyx 

 tube in Arkansas specimens, P. polyandra and P. arkansana Sarg., is 

 less pubescent than is usual in Texas material, but is somewhat 

 variable in this respect even in the same locality. A form, P. tenui- 

 folia Sarg., in the vicinity of Larissa, Cherokee Co., Tex., shows the 

 greatest departure from the usual character of the species of any 

 observed, since it has a finely pubescent calyx with a few longish 

 hairs toward the base and on the pedicels, while the immature fruit 

 indicates an oblong stone. P. reticulata Sarg., was described from 

 Grayson County, Tex. The original material of the species pubhshed 

 by Sargent has been studied, and the characters on which they are 

 based were very carefully considered. They are all of the type known 

 as the big- tree plum, and horticulturally these differences are of less 

 importance than variations in what is still recognized as a single 

 species in P. americana. The rank to be assigned the forms under 

 discussion depends upon one's conception of what constitutes a 

 species. 



Although long confused with Prunus americana and in the her- 

 barium sometimes difficult to distinguish from P. americana lanata, 

 the species is nevertheless a very distinct one. It never forms thick- 

 ets, as does P. americana and its subspecies, but occurs always as a 

 tree with a well-defined trimk, which in the older trees differs in its 

 furrowed bark. The young leaves as they appear are mostly some- 

 what obtuse at the apex instead of acuminate; the older leaves are 

 usually broader in proportion to their length, and the serration of 

 the margin is sHghtly less pronounced. The flowers also have petals 

 somewhat broader in proportion to their length than in P. americana, 

 while the stone is obovoid or round and more turgid. 



