ROSE—-MEXICAN AND CENTRAL AMERICAN PLANTS. 31 
MIMOSACEAE. 
NEW SPECIES OF ACACIA, MIMOSA, AND PITHECOLOBIUM. 
Acacia ambigua Rose, sp. nov. Figure 7, 
Low, somewhat diffuse shrubs, 12 to 20 dm. high, pubescent (even on the old 
wood and thorns), infrastipular spines long and slender; compound leaves much 
reduced, subsessile; pinnze 1 pair; leaf- 
lets 1 pair, 8 mm. long, oblong, obtuse, 
slightly pubescent; flowers in slender 
spikes; legumes linear, 7 to 8 em. long, 
densely silky pubescent. 
Collected on the hills about Matamo- 
ras, Puebla, where it is Common, by J. 
N. Rose and Walter Hough, June 26, 
1899 (no. 4698, type), and near Yautepec, 
Morelos, by J. N. Rose, July 5, 1901 
(no. 5842). 
This species belongs to the amentacea 
group but differs from all the related 
species in its silky pods, ete. 
Acacia compacta Rose, sp. nov. 
A large, round bush 2 to 3 meters 
high; old branches shining, reddish 
brown; young branches grayish pubes- 
cent; leaves rather small; rachis and 
under surface of leaflets somewhat silky 
pubescent; pinme 2 to 5 pairs, 8 to 12 
mm. long; leaflets 12 to 15 pairs, nar- 
rowly oblong, 1 to 1.5 mm. long, obtuse; flowers yellow in dense spikes 2.5 to 3 em, 
Fic. 7.—Pods of Acacia ambigua, 
long; spikes solitary or in pairs forming short naked racemes; calyx minute, silky; 
corolla twice as long as calyx; stamens numerous, distinct; legume oblong, flat and 
thin, | dim, long, 16 mm. broad, acute at apex, shortly stipitate. 
Collected by J. N. Rose and Walter Hough in Tomellin Canyon, Oaxaca, June 24, 
1899 (no. 4680). 
No fruit could be found on the plant, but a single pod, as above described, was 
picked up under the bush. It appeared to belong to it, but I realize that there is 
always more or less risk in collecting and describing detached fruit of any of the 
Mimosae. It is a rule of the writer always to take fruit and flowers when possible 
from the same shrub. This species seems to be related to of. acatlensis Benth., but 
differs in several important respects. It seems best to describe the plant as new. 
Acacia sonorensis Rose, sp. nov. 
Shrubs; branches pubescent; pinnie 1 pair; petiole (very short) and rachis pubes- 
cent; leaflets 2 or 3 pairs, oblong, obtuse, slightly pubescent, 6 to 12 mm. long; 
spikes slender, with very hairy rachis, 2.5 to 3 em. long; legume (immature) linear, 
becoming glabrate. 
Collected by J. N. Rose, near Guaymas, Sonora, June 5 to 11, 1897 (no. 1247). 
Similar to A. amentacea but of different range, with pubescent leaves, ete. 
Acacia macilenta Rose, sp. nov. 
A handsome tree, 6 meters high; the trunk 7.5 to 12.5 em. in diameter; leaves 
large, often with 25 pairs of pinnie; petioles short, bearing a large oblong gland; 
spikes 10 to 12 em. long, in pairs, often forming terminal racemes 2.5 dim. long; 
flowers sweet-sgented; legume with thin valves covered with a close tomentum, 
