NATIVE AMERICAN 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. 
Prunus 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 em. 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 
elandular 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 within 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 in the vicinity 
of Denison, 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 flowers are glabrous or nearly so, while 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 
no promise: whatever. Its rare- occurrence as well as its general 
character suggests that it may possibly be of hybrid origin, and if so, 
the species concerned are P. gracilis and P. reverchonit. 
