SECT. XIH. 



LISTERA OVATA. 



399 



fig. 84, c represents a section of the Epipactis, and D 

 is a front view of the column. 



Of all the British Orchids, the Listera ovata, or 

 Twajblade (fig. 85), has the 

 most curious structure. It 

 grows in woods and pas- 

 tures, has a creeping root, 

 oyal leaves, a downy stem, 

 andyellowish green flowers. 

 Pig. 85 represents a lateral 

 view of a blossom, with all 

 the sepals and petals re- 

 moved, except the labellum. 

 In this plant the rostellum 

 (r) is large, thin, convex in 

 front, concave behind, and 

 arches over () the stigmatic 

 surface. When the flower 

 is full blown, the anther 

 cells (a) are already open, 

 and the naked and friable 

 pollen grains united by a 

 few threads, which form 

 the pointed tips of the 

 pollinia, rest upon the con- 

 cave back of the rostellum. 

 The labellum, which is 

 contracted it the base, is 

 exceedingly long, hanging Fig . 85 . . Listera ovata : _s ide view of flower> 



A nxtm 1 i Ir^ a n * t-rn w ri Khrm with se ^ 3 and P 6 *^ cut awa ^ : a > anther ; 

 down HKe a narrow riUUOIl. wl summit of column ; p, pollen; r, ros- 



It is divided half-way up, 2S g ^ ^ a ; ' M 



and furrowed along the 



middle, from the bifurcation close up to the base of 



the stigmatic surface (s). The borders of the furrow are 



globular, and secrete much nectar. The rostellum is 



internally divided into a series of longitudinal cells, or 



