1904] BILLINGS—TILLANDSIA USNEOIDES IIt 
stretch of the imagination to consider the growth in question asheath, 
there is at least one objection to this solution of the problem. The 
development of the sheath shows that it appears as a bifurcated 
organ almost from its incipiency, and that the base, at first narrow, 
subsequently increases greatly in width. Quite the reverse would 
be true in the embryo if the organ enclosing the growing point were 
regarded as a sheath, for the basal portion is first enormously devel- 
oped, leaving the upper bifurcated portion to appear comparatively 
late. 
The stages in germination are shown in figs. 45-48, which should 
be compared with jig. 49. The latter exhibits a difference in rela- 
tive time of differentiation of stem and leaf apex as compared with 
the seedling. In the mature plant the leaf is still quite small when 
the stem apex becomes distinguishable at its base, while in the seed- 
ling the leaf first attains considerable size. 
THE FLOWER. 
The flowers, which are produced in considerable quantity in May 
and June, present little of special interest. Each flower has a calyx 
of three sepals, and a corolla of three green petals. Having a fra- 
grant odor, it is possible that it is visited by insects, though no infor- 
mation has been collected by me on the subject. Thrips, however, 
inhabit many of the flowers and puncture the style in order to 
deposit an egg at its base. It is possible, therefore, that they may 
serve in cross pollination. 
Although the flower appears to be terminal, it is regarded by 
Mez (6) as a reduced indeterminate inflorescence. An examination 
of preparations made longitudinally through buds bears him out in 
his statement, for a growing point of considerable size is present, 
though having dead meristem tissue. 
THE LEAVES. 
The leaves of T. usneoides are acicular and with an approximately 
semicircular cross section. The epidermal cells do not have specially 
heavy walls, nor are the inner ones thicker than the outer, as in certain 
other Bromeliaceae. Sections through the leaf show it to have three 
fibrovascular bundles, each surrounded by a tissue composed of thick- 
walled sclerenchyma fibers (jigs. 50, 51). The principal portion 
