34 FAMILIAR WILD FLOWERS. 



specific value, while other botanists, less convinced o the 

 reality and permanency of the modification, regard it merely 

 as a variation more or less fleeting and valueless, and consider 

 the plant thus distinguished as but a sub-species at most, 

 or a variety from the true typical form. We may see 

 this very plainly in some other cases ; the number of species 

 of roses, brambles, or willows, for example, differs most 

 widely according as the classification of one or another 

 authority is taken up and adhered to. 



The pink persicaria has long fibrous roots. The stems 

 are numerous, in general growth erect, but freely branch- 

 ing, sometimes indeed so freely as to give the plant a 

 rambling and spreading appearance, though more ordinarily 

 the general growth has a decidedly upward tendency, as we 

 have indicated in our drawing. The stems are often more 

 or less reddish in tint, and at the points where a lateral stem 

 branches off swell very considerably, hence the generic 

 name, derived from two Greek words, signifying many 

 knees or joints, the expansion of the stem and the angle 

 it makes at each point of branching being very suggestive 

 of the knee-joint. At these points the plant is particularly 

 brittle, and snaps very readily. The leaves are lanceolate in 

 form, the lower ones stalked, the upper ones springing direct 

 from the stem, and having at their bases sheathing stipules. 

 The foliage is generally glabrous, i.e., without hairs of any 

 kind, but a variety with hairy leaves is occasionally met 

 with, which has been by some writers elevated to the 

 dignity of a distinct species, under the name of Polygonum 

 incamim. The leaves are very frequently marked with a 

 large dark spot or blotch of purplish-black in their 

 centres, a feature that has procured for the plant its 

 name of spotted persicaria. The numerous little blossoms, 



