so ARETHUSE.E. CJiiap. IlL 



Cephalaiithera offers onlv a partial exception to the 

 '•ule that tlie flowers of Orchids are jrenerailv fertilised 

 by pollen from another plant. 



Cei)lialanthera ensifolia. — According to Delpino,* the 

 flowers of this species are visited by insects, as shown 

 by the removal of the pollen-masses. He believes that 

 this is effected by their bodies being first rendered sticky 

 bv means of the stio;matic secretion. It is not clear 

 ■vviiether the flowers also fertilise themselves. Each 

 j)ollen-mass is divided into two, instead of being merely 

 sub-divided, so that there are four distinct jDollen-masses. 



Fogonia ophioglosscides. — The flowers of this plant, 

 an inhabitant of the United States, resemble, as 

 described by Mr. Scndder, f those of Cephalanthera in 

 not having a rostellum, and in the pollen-masses not 

 being furnished with candicles. The jDollen consists of 

 powdery grains not united by threads. Self-fertilisation 

 seems to be effectually prevented ; and the flowers on 

 distinct plants must intercross, for each plant generally 

 bears only a single flower. 



'■Bterostylis trulh'folia and Jongifolia. — I may here 

 briefly mention some Orchids, inhabitants of Australia 

 hnd' New Zealand, which are included by Lindley in 

 'the same family of the Arethuscre with Cephalanthera 

 and Pogonia, and are remarkable from their labella 

 Ijeing extremely sensitive or irritable. Two of the 

 j^etals and one of the serials form a hood which encloses 

 the column, as may be seen at A in the accompanying 

 figure of Pterostylis Jongifolia. 



The distal portion of the labellum affords a landing- 

 place for insects, in nearly the same manner as with 

 Cephalanthera; but when this organ is touched it 

 rapidly springs up, carrying with it the touching insect, 



* ' Ult. Osservaz. stilla Dico- t ' Vice. P.oston Soc. Nat. Hist 



gamin,' part ii. 1875, p. 149. vol. ix. \^i!)'d, p. 182. 



