452 AMYGDALACEAE 



mm. long; fruit globose, 8-10 mm. in diameter, purplish or red. Cerasus demissa 

 Nutt. River banks: B.C. Ida. Calif.; apparently also Black Hills of S. D., 

 but there a mere low shrub (f. Rydbergii Koehne) . Submont. My-Je. 



12. P. melanocarpa (A. Nels.) Rydb. Tree or shrub up to 10 m. high; 

 twigs reddish brown, glabrous; leaves obovate or oval, abruptly acuminate at 

 the apex, mostly rounded at the base, rather firm, paler beneath, glabrous on 

 both sides; peduncles slender, glabrous or rarely minutely puberulent, many- 

 flowered; petals about 6 mm. long; fruit dark purple or black, 6-8 mm. thick, 

 sweet, slightly astringent, shorter than the pedicels. Cerasus demissa melano- 

 carpa A. Nels. Hills and river banks: Alta. N.D. Kans. N.M. Calif. 

 B.C. Plain Submont. My-Je. 



2. EMPLECTOCLADUS Torr. WILD ALMONDS. 



Low shrubs, with divaricate, spinescent branches. Leaves fasciculate on 

 short branchlets, entire. Flowers 1-3, in axillary umbels, perfect. Hypanthium 

 campanulate, hairy within. Sepals and petals 5, imbricate. Stamens 10-15; 

 filaments slender, distinct. Drupe pubescent, with rather dry exocarp, which 

 splits on one side. Stone bony, flattened. 



1. E. fasciculatus Torr. A shrub 0.5-1 m. high, with divaricate branches, 

 more or less spinescent ; leaves fascicled on short branchlets, spatulate, nearly sessile, 

 5-10 mm. long, finely puberulent or glabrate; flowers sessile or nearly so; petals 

 linear-oblanceolate, white, 3 mm. long; stamens 10-15; fruit subglobose, pubes- 

 cent, about 1 cm. long. Prunus fasciculata A. Gray. Amygdalus fasciculatus 

 Greene. Desert regions: Calif. s Utah Ariz. L. Son. Mr-Ap. 



FAMILY 63. MIMOSACEAE. MIMOSA FAMILY. 



Herbs, shrubs, or trees, usually with twice or thrice pinnately compound 

 leaves, with stipules, the latter often modified into spines. Flowers mostly 

 perfect, regular, in heads or spikes. Sepals 3-6, partly united, valvate. 

 Petals as many, valvate, distinct or partly united. Stamens of the same 

 number, twice as many, or numerous. Pistil solitary, in fruit becoming a 

 legume. 



Legumes flat; valves not separating from the continuous margins. 1. ACUAN. 



Legumes 4-angled; valves separating from the continuous margins. 2. MOBONGIA. 



1. ACUAN Medic. PRAIRIE MIMOSA. 



Perennial unarmed herbs, rarely somewhat shrubby. Leaves bipinnate, with 

 numerous leaflets. Flowers in peduncled heads or head-like spikes, perfect or 

 the lower ones staminate, sometimes without petals. Calyx 5-lobed. Petals 

 5, distinct, or slightly united at the base. Stamens 5 or 10, exserted; filaments 

 distinct or nearly so. Ovules numerous. Pod elongate, unarmed. [Desmanthus 

 Willd.] 



1. A. illinoensis (Michx.) Kuntze. Erect or ascending herb, 3-10 dm. 

 high, glabrous or nearly so; leaves bipinnate, with 20-30 pinnae; leaflets numer- 

 ous, linear-oblong, 2.5-3.5 mm. long; peduncles 2.5-8 cm. long, longer than the 

 pods; stamens 5; pods 4-6 mm. wide, in compact heads, slightly spirally twisted. 

 Desmanthus brachylobus (Willd.) Benth. River banks: Tenn. Fla. Tex. 

 N.M. S.D. Plain. My-Je. 



2. MORONGIA Britton. SENSITIVE BRIER. 



Perennial herbs or shrubs, with spreading prickly stems. Leaves bipinnate, 

 usually sensitive; leaflets numerous, usually small. Flowers perfect or polyga- 

 mous, in axillary peduncled heads. Calyx 4- or 5-lobed. Petals 4 or 5, united 

 to about the middle. Stamens 8-10, exserted; filaments distinct or nearly so. 

 Ovules numerous. Pod narrow, 4-angled, prickly all over, finally 4-valved, the 

 valves separating from the margins. [Schrankia Willd., not Medic.] 



