LEGUMINOS&. SILVA OF NORTH AMERICA. 89 
PARKINSONIA ACULEATA. 
Retama. Horse Bean. 
FLowers in long slender racemes. Legumes 1 to 8-seeded. Leaves long, the 
rachises of the pinne flat, wing-margined, many-foliolate. Branches armed. 
Parkinsonia aculeata, Linneus, Spec. 375.— Miller, Dict. Bentham, Bot. Voy. Sulphur, 87.— Torrey, Bot. Mex. 
ed. 8, No. 1.— Lamarck, Jil. ii. 475, t. 336. — Persoon, Bound. Surv. 59. — Brewer & Watson, Bot. Cal. i. 162. — 
Syn. i. 459. — Willdenow, Spec. ii. 513. — De Candolle, Hemsley, Bot. Biol. Am. Cent. i. 327. — Sargent, Forest 
Mém. Légum. 119, t. 22, f. 112; Prodr. ii. 486. — Trees N. Am. 10th Census U. S. ix. 60.— Coulter, Con- 
Sprengel, Syst. ii. 345.— Don, Gen. Syst. ii. 434. — trib. U. S. Nat. Herb. ii. 94 (Man. Pl. W. Texas). 
Spach, Hist. Vég. i. 108.— Dietrich, Syn. ii. 1496. — 
A low tree, eighteen to thirty feet in height, with a trunk sometimes a foot in diameter, usually 
separating at six or eight feet from the ground into slender spreading slightly pendulous branches 
which form a wide graceful head. The bark of the trunk is brown tinged with red, and an eighth of 
an inch thick, the generally smooth surface being broken into small persistent plate-like scales. The 
branchlets, which are slightly zigzag, are covered with yellow-green puberulous bark during their first 
season, and are glabrous, gray, or light orange-colored, and often roughened with lenticels in their second 
and third years. The leaves are short-petiolate, persistent, light green, and glabrous except for a few 
hairs on the lower part of the young secondary rachises. The spinescent rachises of the leaves produced 
on the young branchlets bear two or four pinne, and develop into stout rigid persistent sharp-pointed 
chestnut-brown spines an inch or occasionally an inch and a half in length and marked near the base 
by the prominent scars left by the falling of the pinne. The stipules of the primary leaves are 
persistent, and appear on the spines as stout lateral spiny branches. In the axils of these enlarged 
rachises fascicles of leaves are produced, each with a short terete spinescent rachis bearing two pinne 
and furnished with minute caducous spinescent stipules. The rachises of the pinne of the primary 
and secondary leaves are flat, a sixteenth of an inch long, conspicuously wing-margined and acute 
at the apex, and bear from twenty-five to thirty pairs of leaflets which vary from a sixteenth to an 
eighth of an inch in length and are oval or obovate, minutely apiculate, and long or short-petiolu- 
late. The flower-buds are oval or obovate, dark orange-brown, a quarter of an inch long and shorter 
than the slender pedicels. The flowers are fragrant, an inch across when expanded, and produced 
in slender erect racemes which are five or six inches long and continue to appear on the growing 
branches during the spring and summer months, or in the tropics throughout the year. The petals 
are bright yellow, the upper one being marked near the base on the inner surface with conspicuous 
red spots, and are much longer than the stamens. The legumes hang in graceful racemes; they 
are from two to four inches in length, long-pointed, dark orange-brown, faintly pilose, and compressed 
between the remote seeds. These are a third of an inch long and nearly circular in section, with thick 
albumen and bright yellow embryos. 
Parkinsonia aculeata is generally distributed in Texas along the valley of the lower Rio Grande, 
where it selects open situations and low wet soil on the borders and around the ends of lagoons ; it 
is common in northern Mexico, in the valley of the Colorado River in Arizona and California, and in 
Lower California. 
It is now well established on Key West, and is widely naturalized in the Bahama and other West 
