141 
The following are found in both rivers: 
Lemna polyrrhiza. Potamogeton lonchites. 
Typha latifolia. Potamogeton pusillus. 
Sparganium eurycarpum. Berula erecta. 
WEEDS. 
Several eastern weeds have come into the region, and many of the 
native plants also act as if they were likely to become more or less 
troublesome. The worst of the weeds introduced is the Russian thistle 
(Salsola kali tragus), but it has not yet established itself firmly. It 
was found along the railroad at Mullen, and more abundantly at Thed- 
ford, while a few specimens were also collected near Plummer Ford, 15 
miles from the railroad. Other weeds or plants likely to become 
noxious are: 
Helianthus annuus. Chameraphis viridis. 
Helianthus petiolaris. Cenchrus tribuloides. 
Chenopodium album. Panicum capillare. 
Chenopodium leptophyllum. Amaranthus albus. 
Chenopodium hybridum. Amaranthus blitoides. 
Acnida tamariscina, Amaranthus retroflexus, 
Portulaca oleracea. Lappula redowshii occidentalis. 
Rumex venosus. Lappula deflexa americana. 
Cycloloma atriplicifolia. Erigeron canadense, 
Eragrostis major. Lepidium incisum. 
Eragrostis caroliniana. Iva xanthifolia, 
Nanthium canadense. Ambrosia artemisiafolia. 
Three plants were almost exclusively confined to the “ prairie-dog 
towns” here as well as in western Nebraska, viz, Solanum triflorum,! 
Oryptanthe crassisepala, Chenopodium fremontii incanum. 
NATIVE TREES AND SHRUBS. 
The most abundant woody plant is Amorpha canescens, which is com- 
mon all over the sand hills. Next comes the Western sand cherry 
(Prunus besseyi). On the sand hills around Thedford the third in 
order is Ceanothus ovatus. Kuhnistera villosa, which should, perhaps, 
be classed among the under-shrubs, is as common as any of the class. 
All these belong to the true sand-hill flora. Nearly all the other 
woody plants are confined to the Middle Loup and Dismal River 
valleys. A few, as, for instance, Salix fluviatilis, Symphoricarpos occi- 
dentalis, Prunus americana, Amorpha fruticosa, are also found in some 
of the wet valleys. 
1Since this report was written a note concerning this plant has been found in 
E. P. James’s catalogue of plants collected on Long’s expedition which reads: ‘J 
have never seen it except immediately about the burrowing places of the marmots 
or prairie dogs, where it is almost constantly found.” 
