FURTHER STUDIES OF YUCCAS. 191 



tion the namejZt/ra for the large Mexican " palma " with 

 drooping panicle, for it has satisfied me that the greater 

 part of Engelmann's Yucca baccata, var. australis consists 

 of another form (from which perhaps one other species with 

 erect panicle, in the upper Mexican plateau, may be sepa- 

 rated ultimately). Y. australis is the large Yucca 

 collected by Thurber about Parras, Coahuila, in November, 

 1852 (no. 1857, in Herb. Torrey.),* and said to become 

 sometimes thirty feet high and two or three feet in 

 diameter, by Bartlett,f who figures a much branched large 

 specimen. It is also mentioned by Baker in the Gar- 

 deners' Chronicle for 1870, p. 1088, under the number 

 26, but without name; and by Engelmann (cf. Col- 

 lected Writings, p. 292), as a variety under baccata. So 

 far as I can judge from herbarium material, it was 

 collected in Mexico by Coulter (no. 1571 in Hb. Gray.), 

 and it appears to be the plant collected in the Carneros 

 Pass, Coahuila, by Pringle in 1889 (no. 2841 ) and 1891 (no. 

 3912). It appears, therefore, to be a species of the 

 northern high lands of Mexico, extending into the elevated 

 Sierra Blanca region of Texas, where it is associated with 

 other southern plants like Agave applanata and A. Posel- 

 gerii. Its nearest described allies, which Mr. Baker tells 

 me have narrow leaves, are Y. periculosa, Baker, and Y. 

 circinata, Baker, both of which, like the present species, 

 have been referred usually to baccata, and which are yet 

 imperfectly known. 



Seedling plants have the blue-green leaves of Treculeana, 

 and possess a cluster of rather fleshy fusiform roots be- 

 coming as thick as one's finger, but no central tap root. 

 With age these roots are replaced by long, tough, cord-like 

 roots as thick as a lead pencil. The trunks at length be- 

 come a foot or two thick, and generally from ten to fifteen 

 feet high, where my observations were made. Though 



* Torrey, Bot. Mex. Bound. 221-2. 

 t Personal Narrative, ii. 490. 



