56 A Study of the Vegetation of 



is it absent. A medium-sized mature plant occupies an area of 

 4-5 square feet ; it may have as many as 50-80 of the large sagittate 

 leaves and a total transpiring surface of 30 square feet. From 

 the short, thick, multicipital stem (I have counted 39 individual 

 leafy shoots on a stem 9 inches in diameter) the new leaves appear 

 in April. By the first of May the plant is often in full bloom. 

 Then, with its large, yellow flowers, it is the most conspicuous ob- 

 ject of the vernal aspect, which lasts until about June I. After this 



FIG. 15. This and the two following figures (15* and 15) are bisects 

 showing the root and stem relations of important prairie plants. These 

 figures were drawn from photographs and from data obtained by the 

 excavation and examination of 325 root-systems- of these eighteen species. 

 H, Hieracium scouleri. K, Koeleria cristata. B, Balsamorhiza sagittata. 

 F, Festuca ovina ingrata. G, Geranium viscosissimum. P, Poa sandbergii. 

 Ho, Hoorebekia racemosa. Po, Potentilla blaschkeana. 



the whole aerial part dries up, but the dead leaves are conspicuous 

 throughout the year. It has a strong, woody tap-root, sometimes 

 reaching a diameter of 4 inches, which may penetrate into the soil 

 for a distance of 8 feet. Not only is it deep-rooted, but the ex- 

 tensive and wide-spreading laterals lay hold upon a very large 

 area of soil. 



In another place will be found a detailed report of a study of 



56 



