FAMILIES OF PLANTS 
51 
Willow dock (Rvmex mexicanus ).—The tufted stems of this species 
are 1 to 2 or more feet high and the lance-shaped leaves, which are 
seldom over 6 inches long, are pointed at both ends and more or less 
folded. The small flowers are perfect and greenish, each having 6 
petals, 6 stamens, and 1 pistil like all members of this genus. 
Figure 34.—Willow dock. Greenish. Photograph by Dr. Harvey E. Stork. 
Rwnex hrittanica is a much larger plant than the preceding spe¬ 
cies. The stems are 2 to 4 feet high, and the leaves are large. The 
leaves are rounded or pointed at the base and decurrent on the stem, 
and they gradually taper to the apex at the other end. 
Rvmex persicarioides is a low, annual plant with linear or lance¬ 
shaped leaves which are 2 to 4 inches long, more or less heart- 
shaped at the base, somewhat wavy margined and mostly on short 
