ORCHIDEAE 395 



perfectly fresh for 30-40, and in some cases for 70 or 80 days, if they are not 

 pollinated. Opportunity for pollination is thus offered to insects for a long time. 

 A flower which has been pollinated, however, fades very quickly, as there is no 

 further need for its remaining fresh. Large numbers of flowers open simultaneously 

 as a rule. In the case of Paphiopedilum and others it also happens sometimes, 

 however, that on a long raceme only one flower is open at a time. As this remains 

 fresh for about a month, the plant can offer a flower to insects for years without 

 intermission. 



Maury (C.-R. Acad. Sci., Paris, ciii, 1886, pp. 357-9) states that the flowering 

 season in our native species usually lasts only ^-2 months. 



Pfitzer goes on to say that insects are attracted to visit the flower partly by its 

 size and beautiful colouring, and partly by particular odours, and there are not only 

 many very fragrant species, but also others which attract carrion flies by their smell 

 of putrefying flesh : Bulbophyllum Beccarii Reichb. f. surpasses the Aroids and 

 Stapelias in this respect. 



Nectar is concealed in very various ways, usually at the base of a spur; this, 

 however, sometimes does not contain free nectar, the secretion being attainable by 

 boring only (e.g. Orchis). 



In order to afford flying insects a convenient alighting-platform, most orchids 

 undergo torsion in the bud through 180 so as to bring the originally upwardly 

 directed labellum to the under-side. 



Some species possess two forms of flowers, e. g. Renanthera Lowei Reichb./., 

 in which the upper flowers of the very long inflorescences are yellow with small 

 brown spots, while the rest are ahnost entirely brown and of a different shape. 

 This peculiarity is most striking in Catasetum, where the same plant sometimes 

 bears flowers of different form in different years, and sometimes all the forms on the 

 same inflorescence. (Justs bot. Jahresber., Leipzig, xvi, (1888) 1890, p. 561.) 



Not only do the visitors to our native orchids belong to the most various 

 groups of insects, but perhaps (in species of Cypripedium) snails sometimes serve 

 as pollinators. Of the better known species the following are pollinated as 

 follows: by humble-bees, species of Orchis, Epipogum aphyllum Sw., Goodyera 

 repens R. Br., Spiranthes autumnalis Rich. ; by bees, species of Orchis, Epipactis 

 palustris Crantz, species of Cypripedium ; by wasps, Epipactis latifolia All. ; by 

 ichneumon-flies, Listera ovata R. Br.; by moths, Habenaria bifolia R. Br., H. 

 conopsea Benth. ; by flies, species of Orchis, Epipactis palustris Crantz, Neottia 

 Nidus-avis Rich. ; by beetles, Listerata ovata R. Br. 



The foundations of the study of orchid flower mechanism have been laid down 

 by Darwin in his classical pioneer work, 'The Various Contrivances by which 

 British and Foreign Orchids are FertiHzed by Insects' (ist Ed., London, 1862), 

 which must be read by every one desirous of understanding the flower mechanisms 

 of this order. In what follows, therefore, I simply give a brief account of the 

 mechanisms of European species. 



817. Orchis L. 



As in many other genera of this order, the three sepals, and the two upper 

 petals form a protecting roof for the central part of the flower. The labellum, 



