

202 BOTANY OF THE DEATH VALLEY EXPEDITION. 



traversed by the expedition has been made the subject of detailed observations 

 by Dr. Merriam, 1 so tbat little need lie said about it bere. As a zonal plant it 

 is cbaracteristic of the upper altitudes of the Lower Monorail zone, where it; is 

 sometimes so abundant that large areas of it have been fitly called yucca forests. 

 The name 'Joshua tree/ by which it is rather jocularly known, is said to have 

 originated among the Mormons. The largest trunk measured was a stump found 

 between Cajon Pass and Hesperia. whose diameter was 58 em.; the tallest speci- 

 men, on the western slope of the Charleston Mountains, was 7.9 meters high. 



The plate of Yucca arborescent, used as the frontispiece of this report, was repro- 

 duced from a photograph taken by the writer in the Mohave Desert, a few kilome- 

 ters north of Victor. 



Yucca baccata Ton*. Bot. Mex. Hound. 221 (1859). Type locality, "High 

 table lands between the Eio Grande aud the Gila," New Mexico. 



In the original description of Y, baccata the following statements occur : "Accord- 

 ing to Dr. Bigelow it is a low species with a subterranean candex," aud "The 

 flowers * * * are larger than in any other species of Yucca here noticed; the 

 sepals being 1\ to 3 inches long, tapering to each end, and 6 to 7 Hues wide in the 

 middle." From these quotations it is clear that the type form of Y, baccata is not 

 1he plant with a stout, arborescent trunk, and flowers 3 to 4 cm. long, which ranges 

 from western Texas to southeastern California, and which goes under the simple 

 name of F, baccata. In the Charleston Mountains of Nevada the writer had excellent 

 opportunity to make a comparison in the held between this arborescent plant aud a 

 related but trunkless one, both of which are abundant in that locality. There is no 

 doubt that in this region the two are quite distinct, differing not only in their 

 stems and flowers but in the color of their leaves, those of the arborescent species 

 being yellowish green; of the trunkless species, glaucous. The latter answers the 

 description of tiue Y. baccata and is so referred, while the arborescent species 

 receives another name as printed below. (See Yucca macrocarpa.) 



Yucca baccata is a characteristic plant of the Upper Sonoran zone. It was observed 

 by the writer only iu the Charleston Mountains, Nevada (Nos. 310,377), but farther 

 eastward and northward Dr. Merriam and Mr. Bailey found it iu several localities, as 

 follows : Indian Spring Valley, Timpahute and Desert mountains, Pahranagat Valley, 

 Ilyko Mountains, Pahroc Mountains, Desert Mountains (No. 191)0), Highland Range, 

 and Juniper Mountains, in Nevada, and the upper Santa Clara Valley and Heaverdam 

 Mountains, in Utah. 



Yucca glauca Nutt. in Eraser, Cat, (1813). Type locality, " 1,(500 miles up the 

 Missourie, about hit. 49°." 



Near Panaca, Nevada (No. 1983). The. plant from Arizona and Utah, which has 

 been referred to this species, is probably different In some respects from the typical 

 form of the. Great Plains region. This is the Yucca angustifolia of Pursh. 



Yucca macrocarpa (Torr.) Bot. Mex. Bound. 222 (1859), as Y. baccata macrocarpa, 

 not Y. macrocarpa Engelm. - 



The smaller arborescent Yucca of the Mohave Desert region, which has passed 

 under the name Y. baccata, is easily distinguishable from the true Y. baccata by the 

 characters mentioned above under that species. The writer has not had an oppor- 

 tunity to investigate the identity of this Mohave Desert Yucca and the arborescent 

 bacciferouB Yucca of western Texas (which also has been called I", baccata, but which 

 is likewise different from that species), but they are supposed to be the same. 



Dr. Torrey wrote: 3 "On the plains of western Texas, near the Limpio, and in the 

 vicinity of Presidio del Norte, Dr. Bigelow found a yucca 10-15 feet high, with 

 eaves almost exactly like those of Y. baccata, but the fruit is longer, though not 



'North American Fauna, No. 7, pp. 353-358 (1893). 

 *Bot. Gaz. vi. 224 (1881). 

 »Bot. Mex. Bound 221 (1859). 



