539 
is usually distinguished by a reddish cast to the spines. Cereus 
viridiflorus is common only in the western half of the territory under 
consideration. 
Many species of plants which may occur scattered here and there in 
the sod of the upland show a preference for broken prairie, such as fire 
guards, roadsides, and piles of earth thrown up by prairie dogs and 
other animals. From this disposition quickly to occupy bare soil they 
become in some cases troublesome weeds. The following are of this 
kind: 
Aristida fasciculata. Helianthus annuus. 
Chamesaracha coniodes. Lappula tecana. 
Chloris verticillata, Malvastrum coccineum, 
Cladothrix lanuginosa, Martynia louisiana. 
Dysodia papposa. Munroa squarrosa. 
Elymus elymoides. Panicum capillare. 
Erysimum asperum. Physalis lobata. 
Euphorbia glyptosperma. Salvia lanceolata. 
Euphorbia marginata. Schedonnardus paniculatus. 
Euphorbia stictespora. Solanum rostratum, 
Gaura coccinea, 
In Schedonnardus, Chloris, and Panicum the whole inflorescence 
breaks away at maturity and “tumbles” before the wind. The first- 
mentioned grass is peculiar in the remarkable growth which takes place 
in the axes after flowering. The main axis may grow to a length of 
2 feet or more, becoming at the same time loosely spiral. In Elymus 
the spike separates and becomes light from the spreading of the long 
awns. Bushels of these spikes will collect in favorable situations. 
Aristida, or “spear-grass,” becomes in fruit very troublesome. Hach 
fruit separates from the mother plant, the three awns reflex horizontally, 
and the wind carries them with the barbed callus forward ready to catch 
in the hair of animalsorin clothing. Its abundance in certain localities 
makes it a great pest. 
On the prairie of the valleys the common plants are 
Andropogon hallii. Astragalus mollisimus. 
Andropogon nutans avenaceus. Elymus canadensis. 
Andropogon saccharoides glaucus. Lepachys tagetes. 
Argemone alba. Sporobolus airoides, or “bunch grass.” 
Astragalus mollissimus is the common “loco-weed” of this region. In 
dry years the bunches are conspicuous from their bright green color 
when the surrounding vegetation is brown. The name loco is applied 
to a number of species of Astragalus and also to Spiesia lambertii. 
The above plants grow in what is usually called the “second bot- 
tom.” Still lower, in the first bottom, and where subject to overtlow, are 
found— 
Acuan illinoensis. Grindelia grandiflora. 
Baccharis salicina, Heterotheca subaxillaris. 
Cleome serrulata. Rhus radicans. 
Euphorbia serpens. Spartina cynosuroides. 
Glycyrrhiza lepidota. 
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