580 MIMOSACEAE 



linear-lanceolate to linear-oblong, 2-5 mm. long, acute, not reticulated : peduncles 1.5-2 

 cm. long, shorter than the subtending leaves : spikes smaller than those of A. Illinoensis: 

 pods few, linear, 5-8 cm. long, straight or nearly so, acuminate at the apex. 



On prairies, Kansas to Texas. Summer. 



3. Acuan Jam&sii (T. & G. ) Kuntze. Stems branched at the base, the branches 

 spreading, 1-5 dm. long, glabrous or nearly so : leaves with 4-12. usually 8-10 pinnae ; 

 leaflets 16-28, the blades oblong, 3-5 mm. long, not reticulated, more or less strongly apic- 

 ulate : peduncles 1-2 cm. long, much shorter than the subtending bracts : spikes about 1 

 cm. in diameter : pods linear, 3.5-8 cm. long, slightly curved, acuminate at the apex. 



In dry soil, the Indian Territory to Texas and Arizona. Spring and summer. 



4 Acuan velutina (Scheele) Kuntze. Stems branched at the base, the branches 

 ascending or prostrate, 2-6 dm. long, finely canescent : leaves with 4-12 or usually 8-10 



Einnae ; leaflets numerous, the blades oblong, 2-5 mm. long, obtuse or acutish, not reticu- 

 ited : peduncles 2.5-6.5 cm. long, shorter than the subtending leaves or longer: spikes 

 about 1.5 cm. in diameter : pods linear, 2-6 cm. long, straight or nearly so, acuminate at 

 both ends. 



In dry soil, southern and western Texas. Spring and summer. 



5. Acuan deprdssa (Willd. ) Kuntze. Stems branched at the base, the branches 

 prostrate, 3-8 dm. long, glabrous or nearly so : leaves with 2-8 pinnae ; leaflets numerous, 

 the blades narrowly oblong, 2-5 mm. long, obtuse or acutish, not reticulated : peduncles 

 as long as the subtending bracts or shorter : pods linear, 4-6 mm. long, acuminate, straight. 



In sandy soil, near the coast, Florida to Texas and Mexico. Spring and summer. 



6. Acuan acuminata ( Benth. ) Kuntze. Stems branched at the base, the branches 

 spreading or prostrate, sparingly pubescent : leaves with 4-8 pinnae ; leaflets 14-20, the 

 blades oblong, 2-4 mm. long, acute, not reticulated, ciliate : peduncles 1-1.5 cm. long, 

 shorter than the subtending bracts : pods linear, 3-4 cm. long, slightly curved, acuminate. 



In dry soil, southern Texas. Spring and summer. 



7. Acuan reticulata (Benth.) Kuntze. Stems branched at the base, the branches 

 ascending or prostrate, 2-8 dm. long, sparingly pubescent : leaves with 4-8, usually 6 pin- 

 nae : leaflets 8-20, the blades oblong to obovate, 3-5 mm. long, very oblique at the base, 

 prominently reticulated, acute or acutish : peduncles elongated, 7-10 cm. long, surpassing 

 the subtending bracts : spikes few-flowered, 1.5-2 cm. in diameter : pods linear, straight, 

 4-6 cm. long, acuminate. 



In dry soil, southern Texas. Spring and summer. 



8. Acuan fallax Small. Stems branched at the base, the branches spreading or 

 prostrate, 1-2 dm. long, finely canescent, angled. Leaves with 4-8 pinnae : leaflets mostly 

 20-28, the blades oblong, slightly inequilateral, 3-5 mm. long, rather obscurely reticulated, 

 acutish : peduncles elongated, 3-7 cm. long, surpassing the subtending bracts : spikes 

 about 1 cm. in diameter : pods linear, 3-4 cm. long, slightly curved, acute. 



In dry soil, San Diego, Texas. Spring and summer. 



10. MORONGIA Britton. 1 



Perennial herbs, or shrubby plants, mostly with spreading or prostrate prickle-armed 

 stems. Leaves usually sensitive : blades 2-pinnate : leaflets numerous, relatively small : 

 stipels setaceous. Flowers perfect or polygamous, in axillary head-like spikes. Calyx 

 4-5-lobed. Corolla of 4-5 petals united to about the middle. Stamens 8-10, exserted : 

 filaments distinct or nearly so. Ovary nearly sessile. Ovules numerous. Pods narrow, 

 prickly all over, 4-angled, or with broad margins, finally 4-valved by the valves separating 

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



Leaflets prominently nerved beneath. 1. M. uncinata. 



Leaflets scarcely, if at all, nerved. 



Sides and margins of the pods with similar or nearly similar prickles. 2. M. angustata. 



Sides and margins of the pods with conspicuously dissimilar prickles. 



Pods scarcely flattened, the sides with long and broad prickles, the margins 



nearly unarmed ; beak 10-15 mm. long. 3. M. latidens. 



Pods markedly flattened, the sides with very fine prickles, the margins with 



stouter prickles ; beak 4-5 mm. long. 4. M. Roemeriana* 



1. Morongia uncinata (Willd.) Britton. Stems armed with recurved prickles, 3-15 

 dm. long : leaves with 6-12 pinnae ; leaflets many, the blades oblong, 3-7 mm. long, 



1 A Mexican species, Morongia aculeata, has been reported from Texas, but I have not 

 yet been able to examine authentic or satisfactory specimens. Species additional to those 

 here recognized have been described by Michaux and Chapman. 



