118 SUMMER FLOWERS. 



Separated by some botanists from the great group of Mono- 

 cotyledons, with which they are associated by others, is a 

 small intermediate group, called Dictyogens, the peculiar fea- 

 tures of which are, that they combine with the floral structure 

 of Endogens (Monocotyledons) the netted venation and woody 

 structure of Exogens (Dicotyledons). Of this group we have 

 two illustrations. 



First, of the family of Dioscoreaceous plants, which con- 

 tains the Yam, we have a native species, the Black Bryony,"^ 

 which bears very much the general aspect of the plants of this 

 family. This Black Bryony, like the cultivated Yams, has thick 

 tuberous root-stocks, and rather slender stems, which twine 

 over hedges and bushes to a considerable extent, in many parts 

 of the country. It is rather an elegant plant in its general 

 aspect, though wanting in beauty of inflorescence. The stems 

 are quite smooth, and furnished with alternate glossy bright 

 green leaves of a heart-shaped figure, tapering to a slender 

 point, and attached by longish stalks. These leaves are tra- 

 versed by a few longitudinal strongly-marked ribs, between 

 which they are occupied by a network of smaller veins. The 

 plant is dioecious, that is, it bears only staminiferous flowers 

 on one plant, and pistilliferous or fertile ones on another. The 

 former grow in long slender racemes, which are often branched 

 and longer than the leaves ; they are individually small, con- 

 sisting of a perianth of six small green segments, and six 

 stamens — quite inconspicuous. The latter, which are equally 

 wanting in attractiveness, and are even less striking on ac- 

 count of their growing in much shorter and less elegant 

 racemes, consist of six segments and a three-branched style, 

 the ovary being inferior; these however are succeeded by 

 bright scarlet berries of globular form. 



* Tamus communis — Plate 19 D. 



