Pool: THE VEGETATION OF THE SANDHILLS OF NEBRASKA 303 



are especially common about old "claims" where small tracts of land 

 were broken up and then allowed to "go back." Such plants are 

 especially common as initial species in the "weed stage" which 

 always precedes the invasion of certain grasses and the reversion of 

 the broken area to one of the grassland associations. The ruderal, 

 Hordeum jnbatum, often completely dominates stretches of plowed 

 ground in valleys and meadows where the stands become especially 

 conspicuous in midsummer. Cycloloma and Amaranthus graecisans 

 are very common old field, fire guard, and garden species of the 

 tumble-weed character. I have seen old fields of several acres in 

 extent covered by the scattered, hemispherical plants of Cycloloma, 

 many of which were more than a yard in diameter. The Russian 

 tiiistle, Salsola tragus, is also common in such places. Dense stands 

 of this plant on "new land" are sometimes cut for hay when young 

 and succulent. Cleome serrulata is especially common in close 

 stands about and within old feed yards and corrals. The night- 

 shade, Solanum rostratum, as also Ambrosia and Argemone, are 

 most frequently seen in similar modified situations. Munroa squar- 

 rosa, Cryptanthe fendleri, and Plantago purshii are common abun- 

 dant inhabitants of prairie-dog" "towns." Common roadside plants 

 are Cassia chamaecrista) Verbena stricta, Dyssodia papposa, and 

 Melilotns especially, as in valleys, where the soil is much more com- 

 pact than up in the hills. The hemp is occasionally seen in charac- 

 teristic stands about stock yards, dump heaps, and similar waste 

 places. The sunflower, Helianthus petiolaris, and the rose dock, 

 Rumex venosus, are among the most noticeable species with a 

 ruderal tendency. The former species often occurs in very dense 

 stands about one-half yard in height over broad fields or in the form 

 of dark green belts following fire guards over the hills. The dock 

 occurs in similar habitats but the appearance is very different be- 

 cause of the low, sprawling plants and the large clusters of very 

 conspicuous, rose-colored to dark red, winged fruits. This feature 

 becomes especially pronounced when the species occurs in extensive 

 stands over relatively bare stretches of the light-colored sand. 



SUMMARY OF SUCCESSIONS 



We have seen that the vegetation of the sandhills is peculiarly 

 grassy, hence any significant alterations in the vegetative cover of 

 this region will be most typically mirrored in the great stretches of 



