DICOTYLEDONS : ARCHICHLAMYDEAE 235 



The Dicotyledons are divided into two great divisions. 

 The first, Archichlamydeae, includes plants which have 

 a relatively simple type of flower. The natural orders of 

 this division embrace flowers increasing in complexity 

 from primitive forms like Willows and Buttercups, with 

 many stamens and much pollen, up to the more highly 

 specialized forms like the Sweet-Pea and Violet, or, as in 

 the Hogweed and Chervil, to small epigynous flowers 

 rendered attractive by being massed into compact inflo- 

 rescences. The second division, Metachlamydeae, is charac- 

 terized by the petals being joined into a flower-tube, as 

 in the Heath and Primrose, accompanied by reduction 

 in the number of stamens and greater economy in the 

 production of pollen and honey, culminating in the aggre- 

 gate flower-heads of the Daisy and Dandelion. In this 

 chapter we shall deal only with the first division. 



(A.) Archichlamydeae. The distinctive features of this 

 division are : the parts of the perianth are either absent, 

 or in one or two whorls ; the inner whorl of petals is free 

 (i. e. the flowers are polypetalous). 



Order Salicaceae. Trees with unisexual flowers in 

 catkins, flowers dioecious, perianth absent. Flowers 

 of the male catkins have two or more stamens in the 

 axil of a bract. Flowers of the female catkins have 

 two carpels in the axil of a bract ; syncarpous ; ovules 

 indefinite. Fruit a capsule. Seeds with a tuft of 

 hairs at the base (see Fig. 185, p. 278). 



The Willows, Sallows, and Osiers are abundant in the 

 North Temperate region, especially in low-lying, wet 

 areas. Many are pollarded (Salix alba, &c.) ; others are 

 coppiced (S. viminalis), and used for basket-making 

 (see p. 277). On mountains in Britain, in the Alps, and in 

 Arctic regions, very small creeping forms occur, only one 

 or two inches high, e. g. Salix herbacea and S. reticulata. 



