Lily-kin and Rose-kin 135 



For there mild winters sometimes favor almost 

 continuous growth, and cambium may be present, 

 and new wood may be formed, during almost any 

 month in the twelve. The rings of a tree (Fig. 

 28) are a trustworthy guide only in northern lati- 

 tudes, where vegetation has a period of vigorous 

 growth followed by a period of torpor. 



In all dicotyledenous trunks the newest wood 



FIG. 28. Crosswise section of the trunk of a young oak-tree, 

 showing growth-rings. 



(From the Vegetable World.) 



lies just beneath the inner bark, and the older 

 wood toward the centre. So a little is added to 

 the girth by each year's growth, till the enor- 

 mously thick trunks of some or our larger forest- 

 trees are built. 



The differences between the rose's kindred and 

 the lily's kindred culminate in their flowers. The 



