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American Midland Naturalist Monograph No. 4 



has also been called heart-nut because of the fruits which are sometimes heart- 

 shaped at the base. These bur-hke pods may cUng to the coats of grazing 

 animals which thus aid in the distribution of the species. 



OccuTTence. — ZION. GRAND CANYON, in the bottom of the canyon. 



Hairy Senna {Cassia Covesi Gray), fig. 

 81. — Low spreading shrub 1 to 2 feet high, 

 the herbage finely velvety; leaves divided into 

 2 or 3 pairs of opposite leaflets, the leaflets 

 oval to elliptic or oblong, I/2 to 1 inch long; 

 flowers few at the ends of the flowering 

 branches; petals 5, yellow, about i^ inch long; 

 pods oblong, % to li^ inches long, about I/4 

 inch wide; splitting down both sides; seeds 

 several. 



Occurrence. — grand canyon, in the canyon, 

 2,500 to 4,000 feet: Colorado River near suspension 

 bridge; Clear Creek trail above Phantom Ranch. 



Honey Mesquite (Prosopis chilensis 

 (Mol.) Stuntz. subsp. glandulosa (Torr.) 

 Standi.). — Much-branched shrub 6 to 10 feet 

 high or a small tree; stems armed with straight 

 sharp spines, these usually borne in pairs at 

 the base of the leaves; leaves divided into 2 

 (or 4) leaflets, these again divided into 9 to 18 

 pairs of small oblong leaflets ^ to I/2 inch 

 long; flowers tiny, yellowish, borne in slender 

 cylindrical clusters 2 to 31/2 inches long, the clusters usually nodding or 

 drooping from the leaf -axils; pods flattened, linear, 3 to 8 inches long, curved, 

 somewhat constricted between the seeds, borne in drooping clusters of 1 to 

 several. (Syn. P. jiiliflora DC. var. glandulosa Torr.). 



Honey mesquite is a characteristic plant of the desert regions. It is excep- 

 tionally drought-enduring and is valuable as a soil binder in erosion control 

 work. The flowers are an important source of a fine quality honey, hence 

 the common name, honey mesquite. The fleshy pods, which are sweet and 

 nutritious, were gathered by the Indians of the Southwest, who ground them 

 into a meal (pinole) which was used for making a mush. Growing as it is 

 in an area where wood is scarce, the roots and stems of this species are highly 

 valued as fuel. Although the leaflets are small and of little value as food 

 for animals, the young twigs are browsed in early Spring. 



Occurrence. — ziON. GRAND CANYON, in the canyon, 2,000 to 3,500 feet: Phantom 

 Ranch; Colorado River near suspension bridge; Havasu Canyon. 



Catclaw Acacia {Acacia Greggi Gray), fig. 82. — Usually a straggly 

 shrub, or sometimes a small much-branched tree up to 20 feet high with a 

 short trunk sometimes 8 inches in diameter; stems armed with stiff back- 

 wardly-curved claw-like spines; leaves twice pinnately divided into very small 



Fig. 81. Hairy senna {Cassia 

 Coves'i). 



