YUCCA MOTH AND YUCCA POLLINATION. tA 
sippi, with the blooming of filamentosa; while other culti- 
vated species which bloom either earlier or later, and which, 
therefore, do not receive the visits of the moth, I have as 
already stated, never known to bear seed. On the western 
plains, where Y. angustifolia is native, the moth’s season of 
appearance is adapted to the flowering of this particular 
Yucca. InCalifornia, Yucca whipple: is pollinized by Pro- 
nuba maculata, an invariably maculate species ; while on the 
Mojave desert, Yucca brevifolia is pollinized by Pronuba 
synthetica, a species still more abnormal than yuccasella and 
modified to fit it to the peculiarities of that peculiar species 
of Yucca. Inthe Gulf States the typical yuccasella occurs, 
and fertilizes not only the filamentose Yuccas, but, as al- 
ready shown, those individuals of the larger, fleshy-fruited 
species like aloifolia which happen to bloom about the same 
time of the year. 
Thus we find that some species of Pronuba is connected 
with all the Yuccas, so far studied in this connection, and I 
have no doubt that this will be found to be generally true, 
so far as the indigenous species are concerned, and that in 
the native home of any of the species we shall find that 
pollination depends upon some species of Pronuba. This 
is rendered certain by the fact that wherever I have 
been able to examine the mature or partially mature fruit of 
other Yuccas in herbaria, I have in almost every instance 
observed the constriction and in most instances seen traces 
of the puncture and the work of the larva. A large and 
interesting form of Pronuba may be expected from the 
Giant Tree Yucca of northeastern Mexico ( Yucca filifera 
Chabaud), the palma of the Mexicans, with its enormous 
pendulous panicles from four to six feet long. ‘The fruit 
is described as often constricted, a result doubtless of the 
work of Pronuba, and the only pod in the herbarium of the 
Department of Agriculture, shows this constriction. This 
baccate fruit is from 2 to 8 inches long and the stigma of 
the young fruit is farther removed from the anthers than 
in any other species. The long, thin, smooth and more 
