204. PARKINSONIA MICBOPHYLLA MOUNTAIN PALOYEBDE. 23 



204. PARKINSONIA MICROPHYLLA, TORR. 



MOUNTAIN PALO VERDE, SMALL-LEAF HORSE BEAN. 



Ger., Gebirgspaloverde ; Fr., Palo Verde de montagne ; Sp., Palo 



Verde de montana. 



SPECIFIC CHARACTERS: Leaves deciduous within a few weeks after their 

 appearance, with common petiole very short or wanting, the pinnae about 1 m. 

 long, pubescent, with terete rachises and 4-6 pairs of small glaucous sessile entire 

 oblong-orbicular leaflets which are obtuse or somewhat acute at apex, oblique at 

 base and about in. long ; branchlets stout, rigid and terminating in stout spines. 

 Flowers May to June, before the leaves, about a half inch across when expanded, 

 in slender racemes 1 in. or less in length, from the axils of leaves of the previous 

 season, the pedicels jointed a little below the flower ; petals yellow, the upper 

 one whitish ; stamens exserted, with orange colored anthers ; ovary appressed- 

 silky. Fruit 1-3-seeded legumes 2-3 in. long, slightly puberulent, attenuate at 

 both ends, contracted between the seeds, which are about | in. in length, with 

 pale brown testa, horny albumen and bright green embryo. 



(The specific name is from two Greek words meaning small leaves.) 



A low tree sometimes attaining the height of 20 ft. (6 m.) with 

 short trunk rarely over 1 ft. (0.30 m.) in diameter, and this dividing 

 near the ground into large crooked sprawling branches, clothed with 

 smooth light yellowish green bark. It forms a wide dome-shaped top 

 close to the ground with a profusion of line pea-green branchlets and 

 scant glaucous foliage. In many localities it is only known as a 

 sturdy shrub. 



HABITAT. The desert regions of southeastern California, central 

 and southern Arizona and southward into northern Mexico. It is 

 known as a tree only in central Arizona, its nature seeming to demand 

 the heat and conditions of those arid regions which few other trees 

 c in endure without irrigation. 



PHYSICAL PROPERTIES. The wood of this tree is rather hard, 

 close-grained, heavy, with poorly denned annual rings and ducts 

 mostly filled with some orange-colored substance making fine 

 reddish dots and streaks in the surface of the finished wood. The 

 heart- wood is of a pale brown color and the abundant sap-wood con- 

 spicuously light yellow. Specific Gravity, 0.744:9; Percentage of 

 Ask, 3.64; Relative Approximate Fuel Value, 0.7178; Weight of 

 a Cubic Foot in Pounds, 46.42. 



USES. Poorly adapted to any use except fuel, for which it is 

 employed in the mining regions of Arizona, and its young branches, 

 serving as very good browse, furnish partial subsistence to herbiverous 

 animals within its arid range. 



GENUS PROSOPIS, LINN^US. 



Leaves bipinnate with one or two (sometimes more) pairs of pinnae, each with 

 several small, entire, rather rigid leaflets; stipules none and petioles, etc.. usually 



