aoy] FLORA OF COLUMBIA AND VICINITY 67 



lawns. It is sometimes found in almost pure communities, but 

 oftener certain clovers, especially the sheep clover (Trifolium 

 repens), and such ruderal grasses as Paspalum setaceum and 

 Panicum sanguinale, are mingled with it. Timothy and orchard 

 grass are common also. As the pastures become worn out, 

 weeds become more abundant, and commonly thistles (Cirsium 

 spp.), mulleins (Verbascum spp.), milkweeds {Asclepias spp.), 

 etc. are scattered freely over such pastures. In lawns the Eng- 

 lish blue grass {Poa compressa) is frequent, and the dandelion 

 {Taraxacum officinale), and the plantains (Plantago spp.) are 

 the chief weeds. 



2. Pratenses. Meadow plants. We may distinguish 

 three kinds of cultivated meadows: a, the grass meadow, 

 consisting of such grasses as Phleum pratetuse, Agrostis vul- 

 garis, and Poa pratensis; h, the clover meadow, consist- 

 ing of Trifolium pratense, T. medium, and T. hybridum. Of- 

 ten the grass and clover meadows are combined; c, the al- 

 falfa meadow, consisting of Medicago sativa. 



a. Pratenses phleoides. The timothy association of 

 meadow grasses reaches its perfection in rich lowlands. Be- 

 sides the grasses mentioned above, several others are sown, such 

 as Festuca elatior pratensis, Bromus inermis, Arrhenatherum 

 avenaceum, Alopecurus pratensis, and Dactylis glomerata. Clo- 

 vers are also frequent, as are the usual meadow weeds, such as 

 Erigeron annuus, E. ramosus, and Onagra biennis. 



b. Pratenses trifolioides. The clover association oc- 

 curs usually with some admixture of the preceding. The same 

 weeds are present, and certain others, especially Rudbeckia hirta 

 and Achillaea Millefolium, are abundant. 



c. Pratenses medicaginoides. The alfalfa association 

 is much less common than the others, the soil in general being 



