NEOTT/E^— EPIPACTIS 57 



Sub-tribe EPIPACTINM 

 Genus III EPIPACTIS Adanson 



Labellum of two dissimilar parts, basal half (hypochile) cup-like, apical half (epichile) 

 cordate or triangular. Stigma quadrangular, rostellum nearly globular on upper 

 edge of stigma. Anther leaning over a shallow cup (clinandrium). Pollinia two, 

 without caudicles. 



Herbs with numerous fleshy roots, with orbicular to lanceolate leaves, and usually 

 one-sided raceme of dull-coloured or greenish flowers. 



SECTIONS 



Arthrochilium Irmisch. 



Hypochile large, oval, petaloid, with two ears. Epichile broad, frilled, with raised 

 yellow plate at base, joined to hypochile by an elastic spring-hinge. Stigma bi-lobed. 



Eu-epipactis Irmisch. 



Hypochile cup-shaped. Epichile only separated by a fold, rigid, with bosses at 

 the base. Stigma not bi-lobed. 



The genus Epipactis is remarkable for the open cup, glistening with nectar, forming 

 the basal half of the hp, resembling that of Goodyera, but the latter is deeper and more 

 pouch-like. The triangular forepart of the lip is also like that of Goodyera, but that 

 of E. palustris more resembles the broad frilled lip of Spiranthes. Another peculiarity 

 is the shallow cup (clinandrium) at the top of the column, over which the anther leans 

 forward, and on its opening by the turning back of a flap on each side, deposits the 

 two pollinia leaning against the back wall of the stigma, their upper ends becoming 

 attached to the rostellum, or viscid gland. The latter is remarkable for its compara- 

 tively large size and simple construction. In early bud it is rough outside and consists 

 of a mass of cells, but develops later into a soft smooth membrane, lined inside with 

 extremely adhesive matter, which sets hard in from 5 to 10 minutes on exposure to 

 the air. It is therefore one of the simplest and oldest forms of rostellum extant, being 

 only a mass of viscid material enclosed in a skin so tender that it can be pierced by a 

 human hair. The globular granules of pollen cohere in fours, but without affecting 

 their shape — the first stage towards the compression of the pollen-grains into tightly 

 packed groups of four (tetrads) to secure economy of space for transport. Cephalan- 

 thera is a still older form in which the grains of pollen are quite separate. Epipactis 

 appears to follow it next in order of sequence with its primitive rostellum, including 

 two or three species in which the rostellum disappears soon after the flower opens, 

 or is even altogether absent. 



