THE TUCCEAE. 85 



frequent vestiges of the marginal characters of both ; while 

 in the color, shape and texture of the perianth, the slight 

 stipe at base of the ovary, the sometimes rather short 

 shouldered style, the mostly pendent indehiscent fruit with 

 thin exocarp drying about a papery core, and the often 

 venously grooved if not truly ruminated seeds, Y. gloriosa 

 holds even more nearly the mean between the two species 

 named. 



The suggestion of a spontaneous hybrid origin of Y. 

 gloriosa offered by this blending in it of the characters of 

 the two other species with which it is most closely associ- 

 ated, would be less strong if Y. gloriosa behaved in general 

 like a normal species of the genus, if it were of greater 

 geographic distribution, or if it occurred in places thor- 

 oughly isolated from the assumed parents. 



As has been said, though locally rather abundant, 

 Y. gloriosa as a spontaneous plant is limited, so far as is now 

 known, to a very restricted region about the Carolina 

 and Georgia coast. It is, moreover, a very unusual species 

 in its life processes. In the arid region of the Mexican 

 table-land, the Yuccas are known to be largely dependent 

 for their blooming season upon necessary rainfall, so that 

 a given species, though usually fairly regular, may bloom 

 in aberrant years at any time between midwinter and mid- 

 summer, and the Pronuba moth which serves as pollinator 

 appears to show a similar susceptibility to moisture in the 

 soil, and commonly emerges from the pupa state synchron- 

 ously with the flowering of the Yuccas. Y. gloriosa, how- 

 ever, growing in a region where the other Yuccas bloom 

 pretty regularly during a rather limited part of the 

 spring, when the Pronuba flies, differs from these species 

 in flowering usually in late summer and autumn, though 

 exceptional flower clusters appear to be developed at almost 

 any season of the year, and the only instances that I cer- 

 tainly know of in which its fruit has been observed were 

 once when early blooming plants cultivated in Washington 



