ROSE AND STANDLEY—PLANTS FROM THE PINACATE REGION, 15 
desert. They dry up, and they drop off—all but the midrib, which takes form as a 
big, woody thorn an inch or more in length. Then and thereafter each stem presents 
the most frightful array of thorns to be found on anything outside the cactus family. 
So far as cattle, burros, and wild animals are concerned, an ocotillo in a state of defence 
is practically impregnable. We saw only two stems that had been barked by food- 
seeking animals, and that work had been done by wild burros, at great trouble and 
expense, 
“Except on the plains dedicated to the creosote bush and mesquite, the ocotillo 
stayed with us from Tucson to the very foot of Pinacate Peak. It is the inseparable 
companion of the giant cactus, but, unlike the latter, it grows larger along the inter- 
national boundary than fifty miles farther north. On the night that three of us ‘laid 
out” on the slope of Pinacate, we found near our bivouac a large dead ocotillo whose 
rods of clean white wood burned with a brilliant light—too bright to last. These 
naked rods are used by the Papago Indians in building fences, and screens around the 
verandas of their adobe houses.”’ 
Petalonyx thurberi A. Gray, Mem. Amer. Acad. IT. 5: 319. 1855. 
Type locality, ‘‘ Valley of the Rio Gila.”’ 
Sandhills, Adair Bay, November 20, 1907, Sykes. 
Sympetaleia rupestris (Baill.) A. Gray; 8. Wats. Proc. Amer. Acad. 24: 50. 1889. 
Loasella rupestris Baill, Bull. Mens. Soc. Linn. Paris. 1: 650. 1886. 
Type locality not ascertained. 
Pinacate Mountains, November 21, 1907, MacDougal 74 
Carnegiea gigantea (Engelm.) Britton & Rose, Journ. N. Y. Bot. Gard. 9: 188. 
1908. PLATE 7. 
Cereus giganteus Engelm. in Emory, Mil. Reconn. 158. 1848. 
Type locality, along the Gila River, Arizona. 
No specimens were collected but many fine photographs were taken. The finest 
specimen seen is illustrated by Doctor Hornaday in a beautiful colored plate.' It was 
about 60 feet high and had 9 branches, an- unusually large number. The species was 
found to range from Tucson to the Pinacates, and from near sea level to an altitude of 
1,200 meters. 
EXPLANATION OF PLATE 7.—From a photograph by Dr. D. T. MacDougal. 
Echinocactus emoryi Engelm. in Emory, Mil. Reconn. 156. 1848. 
Type locality not specifically given; in southeastern Arizona, near the New Mexican 
line. 
A living specimen was collected in the Pinacate Mountains and sent to Washington. 
Echinocactus wislizeni Engelm. in Wisliz. Mem. North. Mex. 96. 1848. 
Type locality, ‘‘Dofiana,’’ New Mexico. 
No material of this species was taken but Doctor Hornaday gives an illustration ? 
of a very large plant from which water is being extracted. 
Echinocereus engelmanni (Parry) Riimpl.; Férst. Handb. Cact. ed. 2. 805. 1886. 
PLaATEs 8, 9. 
Cereus engelmanni Parry, Amer. Journ. Sci. II. 14: 338. 1852. 
Type locality, ‘Mountains about San Felipe,’’ California. 
A cluster of living specimens was collected on the Pinacate Mountains and sent to 
Washington. Doctor Hornaday illustrates a group of these.’ 
EXPLANATION OF PLATES 8, 9.—From photographs by Dr. D. T. MacDougal. 
1 << Camp-Fires,’’ facing page 72. 
2 Thid., facing page 216. 
3 Thid., facing page 236. 
