28 SILVA OF NORTH AMERICA. LILIACEE. 
ol 
broad brown bands on the inner surface; in ripening the capsule splits from top to bottom between the 
carpels and through their backs at the apex only where a triangular opening is made from which the 
seeds are gradually scattered, the empty capsule often persisting until the following season on the panicle, 
whose basé often remains for many years pressed close against the side of the lengthening stem of the 
plant. The seeds are one third of an inch wide and about one thirty-second of an inch thick, with a 
smooth testa, thin brittle wide margins to the rim, and uniform albumen. 
Yucca constricta inhabits high desert plateaus, and is distributed from southwestern Texas to 
southern Arizona and southward in northern Mexico. Rarely exceeding six feet in height in Texas, 
where it is less abundant than farther west, Yucca constricta grows in the greatest profusion and attains 
its largest size on the eastern slope of the low continental divide in southern New Mexico and along the 
northern rim of the Tucson Desert in Arizona, and is found scattered in countless millions over the high 
mesas of many of the valleys of southern New Mexico and Arizona.’ 
The wood of Yucca constricta is light, soft, spongy, and pale brown or yellow. The specific 
gravity of the absolutely dry wood is 0.4470, a cubic foot weighing 27.86 pounds. 
The young panicles, before their branches unfold, are eaten by Indians and Mexicans.’ 
Yucca constricta was discovered by Dr. A. Wislizenus* in the valley of the Rio Grande above 
El] Paso in July, 1846, and the following April it was found in flower by Mr. Josiah Gregg * near the 
city of Chihuahua. 
In appearance Yucca constricta is one of the most remarkable of North American trees, with its 
trunk slender below but thick above from the mass of dead leaves which inclose it, and its broad 
disheveled head of long narrow crowded leaves; and when its great flower-clusters, raised’ high in the 
air on long slender staffs, wave like snowy banners over the desert, it perhaps surpasses all other Yuccas 
in beauty. 
1 The narrow-leaved stemless Yucca of southeastern Utah, which the Colorado plateau, over which, in so far as I have been able to 
has been referred to this species (Engelmann, King’s Rep. v.497.— observe, Yucca constricta does not extend. 
Merriam, North American Fauna, No.7, 358 [Death Valley Exped. ii.]. 2 Palmer, Am. Nat. xii. 646. 
— Coville, Contrib. U. S. Nat. Herb. iv. 203 [ Bot. Death Valley Exped.] 3 See vi. 94. 
[as Yucca radiosa]), is probably an undescribed species common on * See vi. 33. 
EXPLANATION OF THE PLATE. 
Puate DIV. Yucca constricta. 
. Anend of a branch of the flowering panicle, natural size. 
. Vertical section of a flower, natural size. 
. A stamen, enlarged. 
. A pistil, divided transversely, enlarged. 
An ovule, enlarged. 
- The end of a branch of a fruiting panicle, natural size. 
. Portion of a capsule laid open. 
A seed divided transversely, natural size. 
CONATATR ON HB 
- Vertical section of a seed, enlarged. 
— 
oS 
. The base of a leaf, natural size. 
re 
- The point of a leaf, natural size. 
