TWAY-BLADE 



109 



with a pair ol leaves, egg-shaped (hence the second Latin name), near 

 the base, acute, with five marked veins, opposite. 



The flowers are green, small, loosely arranged on a very long 

 narrow raceme or spike. The inner petals are narrower, with a lip 

 divided into two nearly to the base. The column has a crest or 

 appendage, on which the anther is placed. The anthers are yellow, 

 the sepals deep-green, and the petals yellow. When touched the 

 rostellum, one of the stigmas, emits a sticky fluid. 



The Tway-blade is about i ft. high. The flowers bloom in May 

 and June. This orchid is perennial, propagated by division of the root. 



The pollen is fri- 

 able, and if not aggre- 

 gated into a pollen 

 mass would not adhere. 

 It lies above the ros- 

 tellum, and when the 

 latter is touched it 

 exudes a clammy fluid 

 which rises to the level 

 of the pollen. All the 

 visitors are Ichneu- 

 mons except Gram- 

 mop *t 'era l&vis. They 

 attach the pollinia or 

 pollen masses to the 

 head, and apply them 



to fresh stigmas. Alighting on the lower part of the labellum or lip, 

 they creep up, licking the honey in the groove, and raising the head 

 they touch the rostellum, from the side of which fluid exudes. This 

 fluid which rises to the apex of the pollinia cements them to the head 

 of the insect which collects pollinia in each fresh flower. When touched 

 the rostellum bends down to protect the stigma, and while the groove 

 of the labellum is receiving fresh honey it rises, leaving the stigma 

 free for application of new pollinia. The pollinia are erect at first on 

 the insect's head, and then bent down, and they spread apart and so 

 touch the stigma. 



The seeds are light, and easily dispersed by the wind. 



Tway-blade is a clay-loving plant, common on clay soil in ash- 

 woods and in humus soil. 



The leaves of Tway-blade are liable to be attacked by a fungus, 

 Ctzoma orchidis. 



Photo. Flatters & Ga, 



TWAY-BLADE (Listera ovata, Br.) 



