RUTACEAE 439 



Field note. — In the deserts the Creosote Bush is on the whole the most conspicuous woody 

 plant. Vast areas are uniformly dotted with its dark clumps which give a green aspect to the 

 landscape. Sometimes it occurs without marked admixture of other f rutescent species ; fre- 

 quently it is associated with Eurotia lanata Moq., Atriplex confertifolia Wats., A. polycarpa 

 Wats., A. torreyi Wats., Lycium andersonii Gray, Thamnosma moutana Torr. & Frem., Hymen- 

 oclea salsola T. & G., Grayia spinosa Moq., or Ephedra nevadensis Wats., or most often with 

 Franseria dumosa Gray. On the average the individuals of Franseria dumosa outnumber those 

 of the Creosote Bush 10 or 20 to one, but the low gray bushes of the former species make no such 

 show at a little distance, because melting so readily into the desert background. 



Larrea tridentata var. glutinosa is an important zone indicator (Lower Sonoran), its limits 

 being about as follows. On the western Mohave Desert it occurs in the Antelope Valley; on the 

 southern side it is found at Hesperia and the desert end of Cajon Pass ; the northern limits are 

 about Cameron. In Inyo Co. it reaches north to the southerly end of Owens Lake. In eastern 

 Inyo Co. it occurs in Death Valley and in the Panamint Range and Funeral Mts., but commonly 

 is rare though widely distributed. In the Emigrant Canon wash, however, it is abundant. In 

 the Colorado Desert it ranges westward to the foothills of the San Jacinto, Santa Rosa and 

 Laguna mountains (San Gorgonio Pass, Collins Valley, San Felipe Valley, Vallecito) ; eastward 

 it spreads widely over the vast level and is impressively abundant on the great plain which 

 stretches from Holtville to the Algodones Sandhills near Fort Yuma on the Colorado River. A 

 solitary bush or two have been reported from the "Tulare plains" in the upper San Joaquin 

 Valley. This species is one of many in the desert called GreaseAvood. 



To the traveler the distinctive odor of the herbage is its most striking character. To some 

 it is aromatic, to others it is foul, explaining the Mexican name Hideondo. The essential prin- 

 ciple in any event completely protects the bush from grazing animals. The branches occasionally 

 secrete on the surface a sort of gum which the native tribesmen in Southern California and Ari- 

 zona employ for cementing broken pottery and making water-tight their woven baskets. (Pac. 

 Eur. Press 19:178). An analysis of the gum made by J. M. Stillman in 1880 shows three per 

 cent of lac dye and 61.7 per cent of gum lac (Am. Chem. Journ. 2:36). Teamsters in the desert 

 employ a hot-water decoction of the herbage as a liniment for treating collar sores in draft horses. 

 For use as a fuel, desert miners disfavor the entire top of the bush, the whole of which is cut 

 away and the root-crowns then lifted with a crowbar. These compact root masses burn much 

 like bituminous coal or pitchy pine blocks. The stems, on the other hand, which make a quick 

 hot fire, are often the only available resource of the desert traveler, who soon finds that the green 

 ones burn as well as dead ones. 



Locs. — Inyo Co.: Owens Lake (s. end), Jepson; Emigrant Canon Wash, Jepson; Hanaupali 

 Canon, Panamint Range, Jepson 6945 ; Funeral Mts., Jepson. Mohave Desert : Needles, Jepson 

 5487; Riverside Mt., Colorado River, J. Grinnell; Coolgardie yucca mesa, Jepson; Barstow, 

 Jepson 4774; Ord Mt., Jepson; Stoddards Well, Jepson; Old Woman Sprs., Jepson; Victorville, 

 Jepson 5609; Rosamond, w. Mohave Desert, Davy 2929. Colorado Desert: Chuckwalla bench, e. 

 Riverside Co., Schellenger 28; Cottonwood Spr. (Cottonwood Mts.), Jepson; Pinto basin, Jepson; 

 Thousand Palms Canon, nw. of Indio, Jepson 6046 ; Palm Canon of San Jacinto, Jepson 1347 ; 

 Brawley, S. W. Cliilds; Borrego Valley, Jepson; Sentenac Valley, Jepson 12,476; San Felipe 

 Valley, Jepson; Vallecito, Jepson 8582 ; Mason Valley, e. San Diego Co., Jepson. 



Refs. — Larrea tridentata Cov. Contrib. U. S. Nat. Herb. 4:75 (1893). ZygopTiyllum 

 tridentatum Moc. & Ses.; DC. Prod. 1:706 (1824), type from Mexico. Var. glutinosa Jepson, 

 Man. 604, tig. 596 (1925). L. ^^Zwitnosa Engelm. ; Wisliz. Exp. 93 (1848), OUa and Fray Cristobal, 

 N. Mex. Zygophyllum californicum Torr. & Frem.; Frem. Rep. 257 (1845), type loc. western 

 Mohave Desert, Fremont, but a nomen subnudum. Covillea divaricata Vail, Bull. Torr. Club 22: 

 229 (1895) . C. glutinosa Rydb. N. Am. Fl. 25 : 108 (1910) . Schroeterella glutinosa Briq. Veroff. 

 Geobot. Inst. Rubel 3:664 (1925). Neoschroetera glutinosa Briq. Candollea 2:514 (1926). 



RUTACEAE. Eue Family 



Ours shrubs or small trees, with glandular-dotted or aromatic leaves. Flowers 

 regular and symmetrical, or nearly symmetrical. Sepals and petals 4 or 5. Sta- 

 mens (in ours) as many or twice as many, inserted on or outside of a hypogynous 

 disk. Ovary superior, seated on this disk or its base encircled by it. Style 1. — 

 Genera about 111, species about 600, all continents, chiefly tropical and warm 

 temperate. 



Bibliog. — Greene, E. L., The genus Ptelea in the w. and sw. U. S. and Mex. (Contrib. U. S. 

 Nat. Herb. 10:49-78,-1906). Wilson, P., Rutaceae in N. Am. Fl. 25:173-224 (1911). 



Leaves simple. 



Fruit a deeply 2-lobed capsule; leaves alternate 1. Thamnosma. 



Fruit globose, drupe-like; leaves opposite 2. Cneoriditjm. 



Leaves compound; fruit a circular samara 3. Ptelea. 



