PRAIRIE PLANTS OF SOUTHEASTERN WASHINGTON 279 



inches, with a wide spreading top which often covers an area of 

 4 to 5 square feet. It begins blossoming in late May or early- 

 June, and its large red flowers (sometimes as many as 80 to 100 

 in bloom at one time on a single plant) are conspicuous in the 

 estival aspect especially of moist situations. By the second 

 week in July blossoming ceases, but the plant often remains 

 green till late into the summer, if not all fall. 



Geranium has a well-developed tap root which may reach 

 three inches in diameter. It is often more or less decayed and 

 may split up into two or more parts, thus giving rise to new 

 plants. The tap sends off many laterals both large and small 

 at all levels, all of which may branch profusely to the fifth order. 

 The larger laterals usually run off in a horizontal direction, some- 

 times for nearly 3 feet before turning downward. The end of the 

 tap root is either unbranched or branched but little, and is often 

 dead. The bark is reddish and scaly on the older parts. Hard 

 soil seems to be a marked limiting factor to root growth, and 

 under this condition especially the usual very irregular course 

 of descent is greatly emphasized. Twenty-four root-systems 

 were examined. The greatest root depth, 9 feet and 6 inches, 

 was reached on a northwest slope, and an average depth of 5 feet 

 and 3.4 inches was determined. Thirteen plants on a northeast 

 slope gave an average root depth of 4 feet and 8.1 inches,while 

 eleven on a northwest slope reached an average depth of 6 feet 

 and 0.2 inch. 



Wyeihia amplexicaulis (Fig. 14) 



The black sunflower, at home in the moist meadows, also often 

 occurs on rather dry hillsides. Like Balsamorhiza, it is large and 

 abundant and of considerable duration, being conspicuous even 

 after drying out, but, unlike it, its distribution on the high 

 prairies is local and patchy. When we recall that a single 

 plant may have from 14 to 31 leaves, each from 3 to 5 inches in 

 greatest diameter and from 13 to 17 inches in length, the enor- 

 mous transpiring surface may be realized. This shiny, resinous, 

 dark green plant blossoms during the last week of May or the 

 first week of June and rapidly dries up in early July. The 



