NATIVE AMEEICAN SPECIES OF PRUNUS. 59 



appears to have been based on the collection of Lindheimer, "Open 

 post-oak woods west of the Brazos, where it is called 'post-oak 

 plum/" specimens of which are in both the Missouri Botanical 

 Garden herbarium and the Gray herbarium. They are all P. 



gracilis. 



Prtjnus Venulosa Sargent. 



Prunus venulosa Sarg., 1911, Trees and Shrubs, v. 2, pt. 3, p. 157. 



Leaves ovate to oblong-ovate (PI. VII, fig. 2), mostly 5 to 7 cm. 

 long, 2.5 to 3.5 cm. broad, gradually rounded at the base and acute 

 or abruptly acuminate at the apex, dull green and glabrous or some- 

 times sparingly hairy above with short appressed hairs, very reticu- 

 late veiny below, and usually rather strongly pubescent with short 

 hairs, becoming less so with age, the margins serrate and apparently 

 glandular when young, but the glands falling away and usually leav- 

 ing the serrations more or less obtuse, leaf blades only slightly or 

 not at all folded when pressed; petioles 10 to 12 mm. long, with or 

 without one or two glands near the apex, pubescent along the upper 

 surface. Flowers 6 to 7 mm. broad, appearing before the leaves 

 during the latter part of March, in umbels of 2 to 4; pedicels 3.5 to 

 5 mm. long, glabrous or nearly so; calyx campanulate, glabrous or 

 sparingly pubescent, the tube about 1.5 mm. long, the lobes scarcely 

 more than 1 mm. long, ovate, the margin glandular and slightly 

 ciliate, sparingly hairy mthin toward the base; petals 2.5 to 3 mm. 

 long, orbicular and abruptly contracted to a very short claw, erose 

 toward the apex or entire. Fruit globose, 14 to 20 mm. in diameter, 

 dark red, ripening in July, and poor, in quality; stone oval (PL XII, 

 figs. 22 to 24), 10 to 11 mm. long, 8 to 9 mm. broad, and about 6.5 

 mm. thick, somewhat pointed at the base and rounded at the apex, 

 irregularly grooved and ridged near the ventral edge and with a 

 shallow groove along the dorsal edge, the surface smooth. 



Prunus venulosa is a small shrub 3 to 6 feet high, forming dense 

 thickets. Bark of the stem dark gray, the young twigs finely pubes- 

 cent or glabrate, dull reddish chestnut turning dark gray with age, 

 marked with lighter colored oval lenticels. 



The species is known only from a few localities iu the vicmity 

 of Donison, in northern Texas (fig. 3). 



Prunus venulosa is more nearly related to P. gracilis than any 

 other species, but it is a larger shrub and forms more dense thickets, 

 the leaves are larger and more coarsely serrate, and the pedicels of 

 the flowcre are glabrous or nearly so, whOe they are strongly pubes- 

 cent in P. gracilis. The type specimens are preserved in the her- 

 barium of the Arnold Arboretum. Horticulturally the species shows 

 ut) promise vvliulcvci'. Its raic ocfuinciicc as well as its gciiciiil 

 cliurucU'r suggests that it may jjossihly he of hybjid origin, and if so, 

 the Hpt^cics coiHciiicd arc /'. grdci/i.s and /^ rcvnrhonii. 



