294 



PLANTS 



314. Sap. The water and dissolved food which the 

 root takes from the soil rise through the stem to the 

 leaves. This dilute solution is called sap. The sap 

 passes upward through the cells that make up the woody 



layer of the stem. As the 

 tree grows older, the sap 

 leaves the inner wood, 

 which is near the pith, 

 and passes upward only 

 through the outer rings, 

 near the cortex. The in- 

 ner wood is called heart 

 wood ; the outer, sap wood 

 (cf. Fig. 238a). For lum- 

 ber, the heart wood is 

 greatly preferred, because 

 it does not warp as much, 

 or rot as readily, as sap 

 wood. 



The sugar maple stores 

 away sugar in its woody 

 tissue. In the following 

 spring the water that rises from the roots dissolves the 

 sugar, producing maple sap. Men drill holes at intervals 

 into the sap wood, and insert spouts, down which the sap 

 drips into collecting buckets (Fig. 242). When the sap 

 is boiled down, it gives maple syrup and maple sugar. 



315. Buds. Buds are structures for the building of 

 leaves, stems, and flowers (Fig. 243). Leaf buds are a, 

 stem and its leaves in undeveloped form. While in the 

 bud, the stem is very short; so that its nodes are close 



FIG. 242. Collecting Maple Sap. The buckets 

 ought not to be open, and there are too 

 many on the tree. Courtesy of U. S. Dept. 

 of Agriculture. 



