436 



HUTCHINSON'S POPULAR BOTANY 



tridentatum and its female, the Monachanthus,* are further examples (fig. 507), 

 The cup or labdlum which in other species is usually the nectar receptacle 

 is singularly inverted in the varieties specified, and thus is altogether 

 precluded from fulfilling that purpose. Yet, since the sexes stand on 



separate plants, insects must be 

 attracted to the flowers in order 

 to secure pollination ; and insects, 

 like beings of a higher order, will 

 not work except for reward. Dar- 

 win was the first to point out that 

 the labellum itself, which in these 

 varieties is thick and fleshy and 

 of " a pleasant nutritious taste," 

 probably affords food to its insect 

 visitors, and thus answers the pur- 

 pose of nectar, just as do the tubes 

 in Orchis maculatci and 0. mascula. 

 His surmises have been abundantly 

 verified. 



Darwin regarded the genus 

 Catasetum as " the most remark- 

 able of all Orchids." They possess 

 the extraordinary power of forcibly 

 expelling their pollinia when a 

 certain part of the flower the 

 horns or anteniice of the column 

 (fig. 508, an) is touched; and 

 therein lies their extraordinary 

 interest. Observe how the band 

 or pedicel of the pollinium (6), 

 which connects the disc (d) with 

 the pollen-masses (p\ is curved 

 about the projecting rostellum. 

 This pedicel is in a high state of 

 tension. When either of the taper- 



^^^^^^^mi^^^fmsaaa^mammfm^^f^mmm 

 Phol 



[E. Step. 

 FIG. 539. GREEN-WINGED ORCHIS 



(Orchis morio). 



A plant frequently mistaken for the Purple Orchis, but distin- 

 guished at a glance by the parallel green lines along the sepals, 

 and absence of purple spot* from the leave?. 



* So dissimilar is the female flower of 

 Catasetum tridentatum from the male 

 that it was long regarded as belonging 

 to a distinct genus, Monachanthus, and 

 styled M. viridis. Singularly enough, C. 

 tridentatum also bears hermaphrodite flowers, which differ no less in appearance from 

 the male and female forms than do those from one another. Hence the plants producing 

 them were classed with a third genus, Myanthus, under the specific name barbatus. But 

 a plant was discovered bearing flowers of the three supposed genera on one spike, and so 

 the true state of things was recognised, and revision of names made accordingly. 



