MACLOSKIE I LEGUMINOS/E. 489 



blade. Pinnae with 8-n pairs of leaflets, and the rachis prolonged. 

 Leaflets broad-elliptical, or elliptic-lanceolate. Flower-heads axillary, 

 peduncled, globose, is-iy-flowered; one head on the peduncle. Flowers 

 4-merous, 4 mm. long. Legume i-4-seeded, in joints. 

 (Sierra de la Ventana, near Bahia Blanca) ; N. Patagon. 



2. PROSOPIS Linn. Algaroba. 



Trees or shrubs, with bipinnate leaves, spinose or unarmed ; and small, 

 regular, 5-merous flowers in heads or spikes. Petals united halfway. 

 Anthers mostly with a deciduous gland. Legume straight or twisted, with 

 internal cross-septa. 



Species 30, curious both in structure and distribution. Most of the 

 species are in S. Amer., 10 of these in Argentina, and several in Pata- 

 gonia; also 4 species in Mexico, Texas and Calif, i in trop. Africa; i 

 in the Caucasian and Himalayan regions. 



Some species, as P. dulcis and P. horrida of Peru, have pods with sweet 

 mucilage, and form "pastures" which serve as food for cattle. The 

 Mesquit-tree of Texas, P. juliflora DC., yields gum, and is valuable for 

 its hard wood. 



KEY TO THE SPECIES. 

 a. Legume straight or falcate. 



b. Leaves abortive or rudimentary. Spines axillary. humilis. 



b2. Leaf-pinnules i pair. Extra-axillary spines. patagonua. 



b$. Pinnules 2-3 pairs. Apically spinescent. striata. 



bAf. Pinnules 23 pairs. Branches flexuose. denudans. 



5. Pinnules 6-12 pairs. Stipular spines. campestris. 



b6. Pinnules 13-20 pairs. Stipular spines. siliquastriiin. 



a2. Legume contorted. strombulifera. 



i. P. CAMPESTRIS Griseb. Algaroba. 



Shrub, tortuosely intertwined, hirtellous. Stipular spines strong, at 

 length exceeding the fasciculate leaves. Pinna i, rarely 2 pairs, with 

 minute glands between, opposite the dorsal stipel. Leaflets 6-12 pairs, 

 approximate, minute, oblong-linear, obtuse, pilose-margined. Spikes 

 lateral, briefly oblong-cylindric. Pale yellow corolla, puberulous at base. 

 Poof long, 7- 1 1 -seeded. 



(Argentina); Patagon. 



