DISSEMINATION AND LEAF REFLEXION OF YUCCA. 107 
As the leaves of this phytomeroid become reflexed these 
fruits would be freed and fall to the ground. 
Dr. Merriam * mentions the reflexed leaves of arborescens 
(brevifolia) as effectually preventing most animals from 
climbing up the trunk from below. Dr. Merriam informs 
me, however, that the wood rat succeeds in ascending the 
trunk. I quote the following from a letter of February 6th, 
1894: ‘*Mr. Vernon Bailey and I have examined many 
trunks of the tree Yucca ( Y. arborescens) which had been 
ascended by a small desert mammal known as the wood rat 
(Neotoma Mexicana). The wood rats cut off the leaves of 
the Yucca at the base and thus form a spiral groove or ladder 
around the trunk. The leaves are used by the rats in the con- 
struction of their bulky nests which are commonly made up 
of spiny materials such as sharp splinters of rock, parts of 
cactus, leaves of Yuccas, branches of spiny desert shrubs and 
thelike. The heaps of rubbish thus formed over the mouths 
of their burrows constitute a protection against coyotes and 
other enemies.’’ This wood rat which is the only animal 
known to ascend the Yucca trunk, may not have as its 
main object the fruits to be found there. Dr. Merriam 
informs me that he has found freshly cut leaves at a time 
when there were no fruits on the plant: They may merely 
‘desire the leaves for their nests or may feed on the tissue 
of the base of the leaf. 
The habit of certain of the cored species of Sarcoyuccas 
in dropping their fruits as soon as mature, which was dis- 
cussed in the early part of this paper, must be remembered 
here. In these species, baccata, valida, and Guatemalensis, 
the reflexed leaves could hardly be considered as a protec- 
tion to the fruits when these, as soon as they mature and 
become desirable, drop to the ground, — as we suspect in 
order to be gathered and eaten by certain of those animals 
which cannot climb the trunk, the core serving to protect 
* Merriam, C. Hart, “‘ Notes on the Geographical and Vertical Distri- 
bution of Cactuses, Yuccas and Agave in the Deserts of Southern 
California * * * etc.,” 1. c., p. 353. 
