56 PLANTS OF YELLOWSTONE NATIONAL PARK 
Big mouse-ear (Cerastium rulgatum) has also been reported in 
the park. 
Spergularia sparsiflora .—A freely branched, low plant with 
small, lilac flowers, usually 
one to each pair of leaves. 
It is found in wet, saline 
places. 
Spergularia rubra has 
also been found in the 
park. 
Pearl wort (Sagina sagi- 
noides) .-—A dwarf, incon¬ 
spicuous plant of high ele¬ 
vations with linear leaves 
and small, white flowers. 
Figure 36.—Mouse-ear. White. Photograph by Arenaria sajanensis .—A 
Dr. Harvey e. stork. low , densely hairy plant 
with small, white flowers which is common in alpine regions. 
Arenaria congesta , which is smooth or nearly so, is also common 
in the mountains. 
Other species of sandwort that 
have been reported in the park 
are Arenaria aequicaulis , A. nut - 
tallii, A. rossii , and A. tenella. 
Moehringia lateriflora resembles 
the starworts but has broader 
leaves and unlobed petals. 
WATERLILY FAMILY 
(NYMPHAEACEAE) 
A family of water plants with 
many members having very large 
and beautiful flowers but rep¬ 
resented here only by Wokas 
(Nymphaea polysepaia) which 
produces floating leaves that are 4 
inches to a foot long and yellow 
flowers which when fully open are 
3 to 5 inches across. 
Figure 37.— Wokas. Yellow. Copyright, 
J. E. Haynes. 
HORNWORT FAMILY (CERATOPHYLLACEAE) 
A family of water plants with whorled, finely dissected leaves and 
flowers which, unlike those of the waterlilies, are very small and in- 
