45 



By the side of the former species in which every part insures crossing by extraneous 

 aid, it is surprising to find two others which are self-fertilising : H. hyperborea, which 

 morphologically is most similar to H. dilatata, and the very-small-flowered H. tridentata. 

 The pollinia of the former, having very weak and attenuated caudicles, very commonly 

 fall out of the anther cells, while the lip is not yet expanded, or even in the closed bud, 

 and, when the flower opens, they topple over and fall upon the broad stigma beneath. 

 In the other species, the pollinia do not fall bodily out of the cells, but packets of pollen 

 are found detached from them even in the bud, having already fallen down on three 

 clavate and viscid processes of the rostellum into whose substance the pollen sends down 

 copious tubes. The rostellum seems, therefore, to act as a true stigma ; hence it is less 

 extraordinary that the normal stigmatic surface under it should to all appearance be 

 functionless. In both species, however, the glands are perfect, and stick fast to a bristle 

 brought against them, when the pollinia, or what may be left of them, is easily drawn away ; 

 thus crossing is still possible. Mr. J. Fletcher has indeed found as many as three weevils 

 (Stethobaris tubulatus. Say) on flowers of H. hyperborea ; Mr. W. H. Harrington caught 

 also one of the same species on a flower of H. p>sycodes. This .weevil may, therefore f 

 occasionally at least pollinise the stigmas. 



The larger-flowered Habenaria orbiculata, ciliaris, blephariglottis, lacera, psycodes, 

 and Jimbriata have a very long thread-like spur, reaching in the first species to a length 

 of an inch and a half. The nectar can evidently be obtained by long-tongued Lepidoptera ; 

 the pendant lip shows that they must be hawk-moths which feed without alighting. The 

 prompt movement of depression of the pollinia when drawn out of their cells corresponds 

 to the rapid flight of the moths darting from flower to flower. The moth figured in Prof. 

 Gray's Botanical Text-Book, Sphinx drupiferarum, carries two pollinia of H. orbiculata, 

 attached to its eyes, proof positive of a previous visit to a flower. But direct observations 

 were made already in 1863 by Prof. S. I. Smith. He watched a Sesia Thysbe, and on 

 another day a S. diffinis sucking nectar from flowers of H. psycodes.* "They commenced 

 at the bottom of the spike, and, proceeding spirally upward, visited every opened flower 

 in turn. When caught they had twenty to thirty pollinia sticking to the proboscides 

 near the base." The same observer took also a Papilio asterias similarly loaded, and 

 frequently saw "the orthopterous insect, Phaneroptera curvicauda, 8 er v., feeding upon 

 the flowers of the Orchid; but could not find that it ever effected fertilisation in any way, 

 although pollinia were several times found attached to its feet." 



The anther-cells of Habenaria Hookeri are wider apart than in the above species, and 

 consequently a moth arriving in front could easily obtain nectar without touching either 

 gland, but an examination of the flower convinces one that the insect must approach from 

 the side; for the lip curves its point upward, while its edges are turned down on both sides 

 and the lateral sepals are thrown backward. Above all, the orifice of the nectary is heart- 

 shaped, in order to guide more surely an insect's proboscis against the gland above. 



Before leaving the genus Habenaria, I .shall mention the surprising contrast of 

 another species of this continent with the preceding. H nivea of Delaware has like Galo- 

 pogon an untwisted ovary and consequently the spur is turned upward (Gray's Manual, 

 5th Ed. page 681). How pollination takes place with this inverted disposition, is indeed 

 a puzzling question. The legs of an insect will very likely be found to be the means of 

 cross-fertilisation. 



Tribe Cypripedieae. — (Cypyripedium.) 



The large inflated lip in the flowers of the Lady's slippers presents an opening above, 

 while its basal portion is narrower and folded towards the column on both sides so as to 

 form a tube, the roof of which is composed of the sterile stamen or staminodes and the 

 stigma. The edges of the lip overarch all round, except near its base where they leave 

 two symmetrical openings under the two anthers on either side of the base of the column. 

 The pollen is too glutinous to become detached spontaneously from the anthers, and 

 moreover the stigmatic surface is directed downward as if to prevent anything falling 

 upon it. It requires, therefore, a peculiar agent for the pollination. 



* See also Mr. Gibson's article in Harper's Magazine, Dec. 1881, where the plant and a hawk-moth are 

 figured in the usual tasteful style of that publication. 



