212 



PLANT-LIFE 



northerly of shrubs and trees. The Walnut {Juglans 

 regia), a native of Western Asia, and the Sweet Gale 

 (Myrica gale), a low, resinous, fragrant shrub growing 

 on British moors, also belong to the Amentacese. 



The PolycarpiccB (Gr. polys, many; carpos, a fruit) 

 and the Centrospermce (Gr- centron, the centre; sperma, 

 a seed) are also probably primitive among the Chori- 

 petalee. The former are distinguished by usually having 

 free carpels, as in the case of the Buttercups (Fig. 69), 

 in which none of the floral parts cohere. The Buttercups 

 belong to the Kanunculus family, in which there are 



such diverse forms as 



the Anemones, Lark- 

 spurs, and Monkshood. 

 The diversity of form 

 seems to indicate spe- 

 cialization for insect 

 pollination. There is 

 evident advance within 

 the family in this re- 

 spect, but very little in regard to the disposition of 

 carpels and stamens. In the Centrospermge the carpels 

 are usually coherent, and the ovary is always one- 

 celled. The name is due to the fact that the ovules 

 (or single ovule) are central in the ovary, and arise 

 from the apex of the floral axis, which forms a 

 placenta — the term applied to the portion of the ovary 

 bearing ovules. The lower members of the Order are 

 the Sorrels, Docks, Buckwheat, Spinach, Goosefoots, 

 and Beet. These have inconspicuous flowers, and cer- 

 tainly are not the less vigorous for generally being self- 

 fertilized. Higher in the Order we have the Caryophyl- 



Fro. 69, — Section op Flower of 

 [Buttercup (Ranunculus). 



