87 
LEGUMINOSZ. SILVA OF NORTH AMERICA. 
PARKINSONTIA. 
FLoweErs perfect, in axillary racemes ; calyx disciferous, 5-lobed, the lobes slightly 
imbricated or subvalvate in estivation ; petals 5, nearly equal, narrowly imbricated or 
valvate in estivation ; Ovary many-ovuled. Leaves abruptly bipinnate. 
Endlicher, Gen. 1314.— Bentham & Hooker, Gen. i. 
570. — Baillon, Hist. Pl. ii. 171. 
Parkinsonia, Linneus, Gen. 342.— Adanson, Fam. Pl. ii. 
318. — A. L. de Jussieu, Gen. 347. — Meisner, Gen. 98. — 
Trees or shrubs, with smooth thin bark and terete branches often armed with simple or three- 
forked spines. Leaves alternate or fascicled from earlier axils, short-petiolate, the rachis short and 
spinescent with two to four secondary elongated rachises bearing numerous minute opposite entire 
leaflets without stipels ; stipules short, spinescent, persistent, or caducous. 
jointed pedicels developed from the axils of minute caducous bracts, in slender axillary solitary or 
Flowers on thin elongated 
fascicled racemes. Calyx shortly campanulate, the narrow membranaceous lobes nearly equal, reflexed 
at maturity, deciduous. Petals bright yellow, unguiculate, much longer than the lobes of the calyx, 
spreading, the upper one rather broader than the others and glandular at the base of the claw. Stamens 
ten, inserted in two rows on the margin of the disk, free, slightly declinate, included or exserted, those 
of the outer row opposite the sepals and rather longer than the others; filaments villose below the 
middle, the upper one enlarged at the base and gibbous on the upper side; anthers uniform, attached 
on the back below the middle, versatile, two-celled, the cells opening longitudinally. Ovary inserted 
at the base of the calyx-tube, shortly stipitate, pilose, many-ovuled, contracted into a slender filiform 
incurved style infolded in the bud and tipped with a minute stigma; ovules suspended from the inner 
angle of the ovary, two-ranked, anatropous, the micropyle superior. Legume linear, torulose, acumi- 
nate at the two ends, two-valved, the valves thin and coriaceous, convex by the growth of the seeds, 
contracted between and beyond them, and longitudinally striate, the endocarp readily separable from 
the exocarp at maturity. Seed oblong, suspended longitudinally by a slender funicle, the hilum minute, 
near the apex; testa thin, crustaceous, light brown. Embryo inclosed on the sides only by thick layers 
of horny albumen; cotyledons oval, flat, slightly fleshy, the radicle very short and straight. 
The genus Parkinsonia, which contains three species, is confined to the warmer parts of America 
and to southern Africa, where a single species’ occurs. The American species are small trees found 
within the territory of the United States, one in the mountains of Arizona, and the other, Parkinsonia 
aculeata, the type of the genus, along our southern border, where it sometimes has the appearance of 
having grown without the agency of man.’ 
The American species furnish hard close-grained wood. Parkinsonia aculeata has long been 
used in many tropical countries to form hedges, its stout well-armed branches, rapid growth, and indif- 
ference to heat and drought making it valuable for this purpose. 
are cut as food for goats,* and it is said to have supplied the natives of Mexico with a febrifuge and 
In some parts of India the branches 
1 Parkinsonia Africana, Sonder, Linnea, xxiii. 38.— Harvey & recent years. If it is American, it is probably indigenous in the 
Sonder, Fl. Cap. ii. 269. 
2 Parkinsonia aculeata has become widely naturalized through 
the warmer and tropical parts of the world, and its native country 
is uncertain (A. de Candolle, Géographie Botanique, ii. 770). Ac- 
cording to Browne (Nat. Hist. Jam. 222) it was introduced into 
Jamaica from the mainland, and students of botanical geography 
believe that it has only appeared in Asia and Africa in comparatively 
basin of the Rio Grande and on the Mexican plateau, or in some 
high country of western South America, as it is scarcely possible 
that if it had originated in the warm climate of southern Mexico 
or of Central America it would have been able to establish itself 
and spread as widely as it has in a region of such severe cold and 
serious climatic changes as western Texas. 
8 Brandis, Forest Fl. Brit. Ind. 158. 
