240 BRITISH FLOWERING PLANTS chap. 



Matricaria 



M. Chamomilla (Wild Chamomile). — The receptacle, 

 as just mentioned, becomes considerably lengthened. 

 The plant can hardly be distinguished from A. Cotula, 

 except by the absence of scales between the florets. It 

 is glabrous. The achenes secrete mucus, which helps 

 to fix them to the ground and to ensure a definite 

 position for the seedling. 



Anthemis 



This genus closely resembles the two preceding, but 

 is distinguished by the curious character that it has a 

 scale between each two florets. 



There are four British species — three with white 

 flowers, and one, A. tinctoria, with yellow. In A. 

 Cotula the ray florets have no stigma ; A. arvensis has 

 the scales narrow and pointed ; while in A. nobilis they 

 are oblong and obtuse. 



A. Cotula. — As already mentioned, this species has a 

 disagreeable taste and smell, which probably serve to 

 protect it from browsing quadrupeds. The receptacle 

 is conical from the commencement. The ray florets 

 have neither stamens nor pistils. They are only for 

 show. The plant is generally glabrous. 



A. nobilis (Chamomile) is downy and aromatic. 

 A. arvensis has minute silky hairs. A. tinctoria is 

 more downy than the other species. It is not a native, 

 but occurs on ballast heaps and in similar places. 



Achillea 



The flowers are gynomonoecious. 



A. Millefolium (Milfoil or Yarrow). — This species 

 difi"ers from our only other Achillea in having the leaves 

 much divided, while in A. Ptarmica they are linear 

 and serrated. The flower-heads are numerous, small, 

 often over 100 in number, and collected into a dense 

 terminal corymb. Each flower-head comprises about 

 20 disk florets, surrounded by generally 5 ray florets. 



