﻿ADDITIONS TO THE GENUS YUCCA. 



BY WILLIAM TRELEASE. 



Since the publication of my revision of the Yucccae in 1902,* 

 three spontaneous Yuccas worthy of recognition have been 

 discovered. Opportunity to see Uving material of Y. valida 

 from Lower California has led to a re-examination entirely 

 changing my opinion as to the distribution of that species. 

 I have also had opportunity for repeated field observation 

 on a very characteristic arborescent species common in the 

 region about Tehuacan but not represented in the herbaria 

 to which I have had earlier access. The conclusions on 

 these species are embodied in the following annotated de- 

 scriptions : 



ChAENO YUCCA. 



Yucca Harrimaniae Gilbertiana n. var. 



Acaulescent. Leaves 2 cm. wide, about 45 cm. long, openly concave, 

 drying striate, much roughened with prominent points on both faces, 

 very light or blue green appearing almost as if glaucous, with stout straw- 

 colored point; margin brown, with long rather straight and stout pale 

 detached fibers. Flowers about 4 cm. long with narrow acute segments: 

 filaments covered with long thick white papillae: ovary seemingly low- 

 papillate, with oblong pale style. — Plate 12. 



North end of Fish Spring or House Range, western Utah, 

 G. K. Gilbert, Aug. 4, 1901. A little colony on a gravel 

 slope of northern exposure, facing the Salt Lake Desert. 

 Leaf material, slender stiff bracts and detached flowers occur 

 in the U. S. National Herbarium, as well as the remains of a 

 small sterile plant cultivated for a time at the Missouri Botan- 

 ical Garden, from which a few leaves were removed for the 

 Garden herbarium. 



A rather striking form in its very rough papillate leaves, 

 those of the typef being entirely smooth or with a few mostly 

 low papillae near the apex. 



* Rept. Mo. Bot. Garden. 13 : 27. 



t Rept. Mo. Bot. Gard. 13: 59. pZ 28, 29, 83 /. 10, 93. 



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