LEGUMINOSZ. SILVA OF NORTH AMERICA. 49 
OLNEYA TESOTA. 
Iron Wood. Arbol de Hierro. 
Olneya Tesota, Gray, Mem. Am. Acad. n. ser. v. 313 (Pi. 265. — Brewer & Watson, Bot. Cal. i. 157. — Hemsley, 
Thurber.) ; Ives’ Rep. 11.— Torrey, Pacific R. R. Rep. Bot. Biol. Am. Cent. i. 260.— Sargent, Forest Trees N. 
iv. 82; vii. 10, t.5; Bot. Mex. Bound. Surv. 58. — Wal- Am. 10th Census U. S. ix. 56. 
pers, Ann. iv. 587.— Cooper, Smithsonian Rep. 1858, Tesota, Mueller, Walp. Ann. iv. 479. 
Olneya Tesota sometimes grows to the height of twenty-five or thirty feet, with a short trunk 
occasionally eighteen inches in diameter and usually divided, four or six feet from the ground, into a 
number of stout upright branches. The bark of the trunk exfoliates in long longitudinal dark red- 
brown scales. The branchlets are at first thickly coated with hoary-canescent pubescence which 
disappears early in their second year, when they are pale green and more or less spotted and streaked 
with red, becoming pale brown in their third season. The spines, which are often developed in pairs 
below the leaves, are straight or slightly curved, very sharp and rigid, from an eighth to a quarter of 
an inch in length, and persistent during at least two years. The leaves are from one to two and a 
half inches in length, with grooved petioles, and leaflets which are from half to three quarters of an 
inch long. They appear with the flowers early in June, those of the previous year apparently falling 
at the same time. The fruit, which is light brown and very glandular, is fully grown in midsummer 
and ripens before the end of August. 
Olneya Tesota is widely distributed through the arid regions of the southwestern part of the 
continent, from the valley of the Colorado River south of the Mohave Mountains of California to 
southwestern Arizona, the adjacent portions of Sonora, and Lower California.’ It occupies the sides 
of low depressions and arroyos in the desert, and in some portions of its range, especially in Sonora, 
where it is more abundant and grows to a larger size than in any part of the United States, it is a 
common tree. No other desert tree is more beautiful than the Tesota when its abundant racemes of 
large bright flowers are clustered on the end of the branches; and in recent years a number of attempts 
have been made to introduce it into the gardens of southern Europe, where, however, it has resisted 
every effort at domestication.’ 
The specific name Zesota is that by which this tree, the Arbol de Hierro of the Spaniards in 
Mexico, was known to the inhabitants of Sonora at the time of its discovery. 
1 It was found in Lower California by T. S. Brandegee between 2 The seed germinates readily, but the seedling plants soon be- 
Comondu and Calamujuet (Proc. Cal. Acad. ser. 2, ii. 149 [Pl. Baja come sickly, and perish at the end of a few weeks (Naudin, Garden 
Cal.]). and Forest, iv. 324). 
