52 
PLANTS OF YELLOWSTONE NATIONAL PARK 
petioles. The greenish flowers are produced in numerous dense 
whorls along the slender branches. 
Rumex oocidentalis is a large plant, usually 2 to 4 feet tall and 
rather stout. The leaves are somewhat fleshy, smooth, and glossy, 
bluish green in color, wavy-margined, ovate or oblong in shape, 
somewhat heart-shaped at the base, and rounded or pointed at the 
apex. The whorls of greenish flowers are arranged in dense panicles 
which become rosy as the fruits mature. 
Wild-begonia ( Rumex venosus) .—This species can be recognized 
by the inner segments of the perianth, which are about an inch broad 
and bright rose color. 
Polygonum.— The polygonums are herbaceous plants with alter¬ 
nate, entire leaves and with the swollen nodes of the stems 
encased in sheaths which are more or less fringed or lobed. The 
flowers are borne in terminal spikes with dry bracts. The calyx 
is usually 5-parted and more or less petallike. The stamens vary 
from 4 to 9 and the styles or stigmas from 2 to 3. There are no 
petals. 
American bistort ( Polygonum bistortoides) .—This species grows 
from 1 to 2 or more feet high. There are relatively few leaves, and 
they vary from oblong to linear or lance-shaped. The basal leaves 
are on long petioles, while the upper ones are sessile and smaller. 
The plant is most easily recognized by the short dense spike of white 
flowers which are sometimes tinged rose color. 
Polygonum viviparum has smaller flowers and the lower ones on 
the spike are replaced by little bulblets. 
Water ladysthumb ( Polygonum amphibium) grows in water with 
the thick, smooth, long-petioled, elliptical or lance-shaped leaves 
floating. The bright, rose-colored flowers are borne in a terminal 
spike, which is dense but only about an inch long. 
Polygonum hartwrightii is quite similar but usually grows in 
mud. It is very leafy and more or less hairy. 
Knotweed ( Polygonum aviculare ), Cornbind (P. convolvulus ), P. 
erectum , P. douglasii , and P. polygaloides are somewhat weedy 
plants and not very important in the park flora. They may be dis¬ 
tinguished by means of the key. In addition to the species included 
in the key Polygonum engelmanmi , P. spergulariaeforme , P. wat- 
sonii , and P. keUoggii have been reported as occurring in the park. 
G00SEF00T FAMILY (CHENOPODIACEAE) 
The goosefoot family is a large family of weedlike herbs and 
shrubs with simple, alternate leaves and small, greenish flowers. 
Many of them are adapted to growing in deserts or in sandy or 
saline soils. Most of them are wind-pollinated and produce pollen 
