GROUP IV. PHANEROGAMIA : ANGTOSPERM^ : MONOCOTYLEDONES. 565 



of sticky mucilage (retinacula) are formed, and are frequently 

 enclosed in one or two pouches (bursiculce) formed by the rest of 

 the tissue of the rostellum. The pollinia adhere to the retinacula 

 by the caudicle, when present, and are removed, in pollination, by 



Fio. 371. Tubers (A) of Orchis Morio ; B of tiymnadenia Conopsea : s the peduncle ; 1 this 

 year's tuber ; 2 next year's tuber ; fc the bud ; w and w' roots (nat. size). 



the adhesion of the retinacula to the proboscis of the insect (see 

 p. 456). 



Most of the indigenous species have underground rhizomes or 

 tubers. In the latter case, two 

 tubers are usually present : the older 

 one, which, at the time of flowering, 

 becomes flaccid (Fig. 371 A and J5, 1), 

 throws up the flowering scape (s} 

 or, in young plants, a short under- 

 ground stem which produces only 

 leaves above ground. At the upper 

 end of this tuber another much 

 firmer tuber is formed (Fig. 371), 

 bearing at its apex the bud of the 

 next year's stem (K). The tuber is 

 to be regarded as a lateral bud 

 which coalesces with its first root 

 (or more than one, Fig. 371 B) and 

 then increases in bulk : the lower 

 end of an undivided tuber, as well 

 as the ends of palmate tubers, has, 

 in the young state at least, the same 

 structure as the apex of a true root. 



FIG. 372. Flower of C[/jmj>edium 

 Calceolus ; p p the leaves of the peri- 

 anth have been cut away. A Side 

 view. B Back view. C Front view; 

 / ovary; gs gynostemium ; a a the 

 two fertile stamens ; s staminode j n 

 stigma. (After Sachs.) 



