TET, OR CEN ree prem 
DISSEMINATION AND LEAF REFLEXION OF YUCCA. 103 
plant at a distance of about a meter, having been thrown 
there in falling by the action of the reflexed leaves. 
While this is not the main method of dissemination, I 
think that it may reasonably be claimed to form a second- 
ary method of considerable importance. 
After reaching maturity the fruits remain fresh and soft 
for a few weeks but gradually dry up until nothing remains 
but a dried fragment of the pulp which cements the seeds 
together into a small light mass. Long before they have 
reached this thoroughly dry condition they have passed 
the stage when the birds will eat them. Sometimes the 
dried fruits are broken off as a whole and these, falling, 
strike the reflexed leaves and are thrown outward to some 
distance as they fall to the ground. The fruits may now 
be knocked about by man or animals or may become disin- 
tegrated in the place where they fall. This would also serve 
to disseminate the seeds to some extent. Many of the seeds 
still remain sound and evidently capable of germination. 
A still more peculiar aid to dissemination is found in the 
larvee of the Bogus Yucca Moth (Prodoxus decipiens Riley) 
which is very common here and probably throughout the 
aloifolia region. 
The eggs of Prodoxus are deposited principally in the 
young flower stem, though it is said by Riley * that 
they are also found frequently breeding in the fruits of the 
indehiscent Yuccas like aloifolia. I have never observed 
them in the fruits of aloifolia, though I have made no 
special attempt to find them. The incision on the young 
peduncle made by the ovipositor leaves a discoloration 
and forms ultimately a sort of cicatrice which remains dis- 
tinctly visible and as the stem dries becomes slightly 
elevated (Plate 47, fig. 3, b). The larva burrows in 
the tissue of the peduncle, molts according to Riley three 
times, and acquires full growth in a month. ‘ It pre- 
pares for hibernation in the autumn, a cocoon of white 
* Riley, C. V., “Yucca Moth and Yucca Pollination,’? Mo. Bot. 
Garden, 3d Annual Report (St. Louis, 1892), p. 128. 
