36 
PLANTS OF YELLOWSTONE NATIONAL PARK 
stem. The most conspicuous member of the family is a cotton- 
sedge ( Eriophorum ocreatum) . It grows in cold, boggy places and is 
readily recognized by its large, cottony head when in fruit. Fol¬ 
lowing are the names of other members of the family that have been 
identified in the park: 
Sedge (Gar ex ) 
Car ex ahlata 
Carex acutina 
Carex alpina 
Carex athrostachya 
Carex atrata 
Carex aurea 
Carex canescens 
Carex concimxa 
Carex deflexa 
Carex diandra 
Carex disperma 
Carex douglasii 
Carex festiva 
Carex geyeri 
Carex hoodii 
Carex jonesii 
Carex lanuginosa 
Carex liddonii 
Carex longirostris 
Carex marcida 
Carex petamta 
Carex piperi 
Carex praticola 
Carex preslii 
Carex pseudoscirpoidea 
Carex raynoldsii 
Carex rostrata 
Carex saxatilis 
Carex siccata 
Carex tenuirostris 
Carex utrioulata 
Carex vallicola 
Carex vesicaria 
Carex viridula 
Carex xerantica 
Spikemsh ( Eleocharis ) 
Eleocharis acicularis 
Eleocharis palustris 
Eleocharis thermalis 
Bulrush ( Scirpus ) 
ficirpus americanus 
Scirpus occidentalis 
DUCKWEED FAMILY (LEMHACEAE) 
The plants of this family are very small and float on the surface 
of ponds and slow-flowing streams. They have neither stems nor 
leaves. The plant body consists of one or more small, flat, disklike 
bodies, each with a single rootlet hanging down into the water. The 
flowers are very small and are seldom seen. It is the smallest of 
flowering plants. 
Eairypaddle (Lemna trisulca ).-—This species has an elongated 
plant body which is narrowed at the base into a stalk. It sometimes 
becomes so abundant that it forms a thick mat over the entire sur¬ 
face of a pond. 
Lemna minor with a rather thick and nearly circular plant body 
and Lemma gibba with an obovate but unsymmetrical body have also 
been reported in the park. 
RUSH FAMILY (JUNCACEAE) 
This is another family of grasslike plants. Although the flowers 
are lilylike in structure, they are very small and inconspicuous. The 
