TREES AND SHRUBS 



95 



united; fruit a more or less flattened dehiscent or indehiscent le- 

 gume. 



1. ACACIA. 



Strombocarpa. 



Prosopis. 



ACUA.N. 



Mimosa. 



Stamens numerous, always more than 10; cor- 

 olla polypetalous; stamens distinct. 

 Stamens 5 or 10, distinct. 



Flowers 5-merous, anthers tipped with a 

 gland; pods indehiscent, large shrubs. 

 Pod spirally coiled; flowers yellow. 

 Pods elongated, not coiled; flowers green- 

 ish. 

 Flowers 4- to 5-merous; anthers not gland 

 tipped; pods dehiscent, flatterend; leases 

 not sensitive or at most, tardily so; plants 

 erect or spreading. 

 Plants without spines of any kind; stems 



mostly herbaceous. 

 Plants armed with numerous, short, re- 

 curved triangular spines; shrubs with 

 woody stems. 



I. ACACIA L. 



Shrubs or low trees with armed or smooth stems and bipin- 

 nate leaves with numerous very small leaflets; flowers small, reg- 

 ular, in spikes or heads on axillary peduncles; corolla valvate, of 

 4 or 5 similar petals; >tamens numerous, distinct, exserted; pod 

 flattened or terete. 2-valved, dehiscent. 



Flowers in elongated spikes; pods flat, % to ; ;4 



inch wide: curved; spines short and hooked. 1. A. greggii. 



Flowers in globose heads; pods terete, or if flat 



less than u inch wide, straight; spines 



straight and slender or none. 



Spiny shrub 3 feet high or more; flowers 



bright yellow, sweet-scented; pods terete, 



constricted between the seeds. -. A. constricta. 



Unarmed shrubs less than 3 feet high; flow- 

 ers whitish, odorless; pods flat and thin. 

 Leaflets 8 to 13 pairs, obtuse; inflorescence 



nearly always axillary. 3. A. cuspidata. 



Leaflets 18 pairs or more, acute; inflores- 

 cence becoming paniculate, sometimes 

 axillary. 4. A. filicioides. 



2. STROMBOCARPA A. Gray. Screwbean Tornillo 



A tall gracefully spreading shrub 15 feet high or less, branch- 

 ing from the base, with dense, dark-colored wood; leaves small, 

 bipinnate, with 1 or 2 pairs of pinnae: leaflets 5 to 8 pairs, short- 

 oblong; young parts pubescent: stipular spines rigid, % inch long 



