oct.iflw.] H. TAKEDA.—ON THE GENU& IC'J it*' 



each of which consists of a normal flower and one or sometimes 

 two imperfect flowers borne on the side of the torus of the 

 former. These imperfect flowers consist either of three stamens 

 and a rudimentary pistil, of six stamens and a rudimentary pistil 

 or even six stamens and an abortive pistil, (pi. VII, figs. 1— t, 

 22-27). These facts account for the disagreement among 

 botanists as to the number of stamens present in a single flower. 



The Fruit. 



The fruit is an achene ; the pericarp is cartilaginous, dark- 

 brown in colour, and smooth. It is 3—4? mm. long and of the 

 same bredth, nearly reniform, and is strongly convex on the 

 dorsal side and concave on the ventral side with a longitudinally 

 wrinkled ridge or column (pi. VII, figs. 28-29, 34-36). 



As a rule a comparatively small proportion of the flowers 

 are fertilized, so that only a few achenes are produced in a spike 

 (text-fig. Ill, 2 and 3). 



The seed is erect, covered with a thin testa, albuminous, 

 and contains a small embryo. 



The Species of this Genus. 



It has already been mentioned that only two species have 

 up to the present been described, and one of these has been 

 reduced to the other as a variety. Since both the foliar and 

 floral characters are so much alike and so very much reduced, 

 it is not an easy task to discriminate species. Pro's reason tor 

 his reduction of A. japonica to A. triphylla is that these plants 

 differ only in size (11, p. 435) X) . If we, however, closely examine 

 these two plants we find certain other important features by 

 means of which we can distinguish them as two distinct species. 

 In A. triphylla the terminal leaflet, when very well developed, 

 always produces a number of larger and smaller shallow tri- 



1) Ito's description of the leaflets is unintelligible. It appears, however, he 

 that the terminal leaflet is trilobed at the apex and otherwise entire. 



