58 TRANS. ST. LOUIS ACAD. SCIEXCE. 



umbels is curiously constructed so that the pollen-masses, which 

 look like little flattened, ovoid pieces of wax. can only come in 

 contact with the stigma by artificial means ; and we find that they 

 hang by a bent stalk, attached to a flattened, ovoid, brown organ 

 having a cleft which catches the claws or tarsal hairs, or the fine 

 hairs surrounding the trophi, of insects climbing over the umbels. 



With most of the plants of this kind, now known, fructification 

 may be brought about by the aid of more than one species of in- 

 sect ; and none, perhaps, offer a more striking instance of depend- 

 ence, or more curious floral mechanism to allure, than do the 

 Orchids. They display an infinitude of curious contrivances and 

 adjustments for the purpose. In the genus Habenaria, for in- 

 stance, the peculiarities of which are described by Dr. Gray, we 

 find flowers that, in some cases, strongly recall butterflies ; a se- 

 parate pocket for the nectar ; the pollen bound together in masses 

 by elastic threads so as to lessen the chances of loss ; and the base 

 of the stamens forming flattened, sticky discs, placed in the best 

 possible position for adhering to the head parts of a moth or but- 

 terfly endeavoring to reach the nectar. In all these features, and 

 others that might be mentioned, there is remarkable adaptation ; 

 and the flowers of many species, as they unfold their petals, seem 

 not only to invite, but to court and crave, the intervention of some 

 scaly-winged marriage priest of "glorious color and glistening 

 eye" who shall at once procure a suitor and perform the nuptials. 



Yet here we have adaptation of the plant only, and except 

 in one or two rare instances, as, for instance, in that of a 

 Madagascar Orchis {Angrcecum sesqidpedale), where the nec- 

 tary is so deep that its nectar can only be reached by a moth 

 with a very long tongue, our Orchids are not dependent for 

 pollenation on any one Lepidopterous species, but may be 

 aided by many which have tongues of sufficient length. Our 

 Yuccas, on the contrary, seem to depend for assistance, so far 

 as we now know, on the single little Tineid which I have 

 described, and for this reason are among the most interesting of 

 entomophilous plants. At least such is the case with the cap- 

 sule-bearing species, i. e. those which have dry, dehiscent pods ; 

 and I will here premise that my observations have been made* 

 upon a filamentose-leaved species, in common cultivation about 



* The fructification of such Yuccas as bear fleshy, pulpy fruit, of which T. aloifolia may 

 be taken as the type, has not been studied; but, even with this last mentioned species, the 



