346 BRITISH FLOWERING PLANTS chap. 



membranous, smooth, but not shining coat. They are 

 mixed indiscriminately on the panicle. The large brown 

 ones germinate much more quickly than the small black 

 ones, which would seem, under natural conditions, to be 

 more adapted to remain in a resting condition in the 

 ground during the winter and germinate in spring. If 

 such is the case they would enable the plant to exist in 

 a colder climate than the large ones would. ^ The plant 

 occurs in Britain as a garden escape. 



POLYGON A CE^. 



In this family also the flowers are small, but contain 

 nectar, and are often conspicuous by association. They 

 generally contain both anthers and pistil. Many species 

 are dimorphous. 



EuMEX (Dock) 



The British species are all perennials. The flowers 

 are generally reddish. The parts of the flower are in 

 threes. The Sorrels have hastate leaves. The true 

 Docks are generally distinguished by the form of the 

 perianth segments and the tubercles on them. The 

 function of these tubercles is not known, nor has any 

 suggestion been offered as to why some species (B. 

 aquaticus) should have none ; others {R. crispus and 

 B. sanguineus), one on one at least of the perianth seg- 

 ments, while R. conglomeratus, as a rule, has one on 

 each segment. 



R. crispus. — The leaves are much waved or crisped 

 at the edges. The flowers are protandrous, and the 

 pollen is wind-borne. Some are complete, some are 

 male, some female ; these last are generally small. 



R. obtusifolius. — Kirchner describes the flowers of this 

 species as resembling those of R. crispus. Kerner, how- 

 ever, found those examined by him to be protogynous. 



' Avebury (Lubbock), On Seedlings, vol. ii. 



