174 
tuate their hissing. The growth of this plant is evident only in 
the development of its flowers and fruit, and in the lengthening 
of the shaft after the first two weeks of the rainy season, which 
commences about August 1. The flowers are trumpet shaped, 
green externally, with numerous white petals, and are produced 
at the tops of the stems (Fig. 27). The tube is always crowded 
with small insects, chiefly of two kinds, a beetle and a wasp. 
Although the size of the flower might lead one to expect that it 
would be pollinated by a larger form, it would appear that these 
litte insects are in part, if not wholly, saan sa or the opera- 
tion, The fruit when ripe is oval, about three inches in length and 
yellowish green in color and is surmounted by the long withered 
and hardened corolla tube. When fully mature, the pericarp 
bursts, exposing the crimson interior tissues. The cavity is filled 
with a pulp, derived from the long branched seed-stalks, in which 
are imbedded the numerous black seeds. The opened, highly 
colored fruits are more striking in appearance than the flowers, and 
at even a short distance readily deceive one unfamiliar with the 
ant who mistakes them to be flowers. At the time of mai 
and fruiting, the tops of the stems have a curious unkempt aps 
pearance. The fruit is much sought after by the Pree sank 
Indians as food. The pulp tastes somewhat like that of a fresh 
fig, but borders on the insipid. 
The ocotillo is a leafy shrub which attains a height of about 12 
feet and is readily noted by virtue of its peculiar habit. At the 
base there is a short thick stem from which arise twenty-five or 
thirty unbranched tapering stems which take an oblique position, 
giving to the whole plant the form of an inverted cone. During 
a period of drought, the stems are leafless, but after rain bey 
glaucous leaves. The stems then look like green cylindrical 
rods, easily swayed by the wind, and, with the giant cactus, give 
the most characteristic feature to the flora. I may here add that 
the ocotillo chiefly engaged my attention during the six weeks 
spent at the laboratory, my work being directed at the correlation 
of transpiration and stomatal action. 
