159 



huucli-fortners. 'i'tiree other grasses, Si/iithrj'i.sHui fi/iformls. 

 Arisfnid f/il)cn'ii/<>s((. and Cei/chnis trihiilolilcx. and two sedges. 

 t'l/penis Hus/iii and ('. fi/lr/i/nn.s. ave ahnndant, hut do not fonii 

 hunches. 



The distribution of the remaining niemliers of the associa- 

 tion, about Hfty in number, is very irregular, and a group of 

 representative species can not be chosen from them. I^nsn Im- 

 iniihs. So//(l(i(/(i Hiissiuirii'iis/s. Amorplid cnncsccns, Opinifia Ininii- 

 fuxii. ('(i/ilrr/ior friain/ii/afd. and MniKirda /iiincfafii are the ino.st 

 conspicuous. l)ut as the quantitative study of the plants shows, 

 not so numerous as 'l\ncninii ciniinhiisi .m' A ii/lirdsio /isi/iisfuc/u/n. 

 With tlie exception of Moininln /'mtftntd and the hist two species, 

 these grow in rather dense, rounded patches. The same is true 

 to a lesser extent of almost every other species in this class, 

 but since the individuals are smaller or less al)undant. many 

 other species may l)e included, or two or more patches, each 

 with traceable outlines, may overlap, if the [)lants are at all 

 conspicuous the overlapping is plainly seen, and in any case it 

 is l)rought out by quantitative study of the area. This form of 

 distribution is characteristic of a.s.sociations where there are no 

 progressive changes in any of the ecological factors, and conse- 

 quently no zonal arrangement of the plants. Annuals with 

 limited means of seed dispersal, and i)ei'ennials spreading by 

 rootstocks or runners, naturally grow in rounded jiatches un- 

 der those conditions, it is evident, then, that wliile the bunch- 

 grasses are representative, the other species, of merely local 

 distribution, are to lie considered as secondary members of the 

 association. 



Table 1. shows the distriluition (^f the sfiecies in a piece of 

 original bunch-grass i)rairie. The letters after eacdi name here 

 and in subsequent tallies, indicate the number of individuals, if 

 any, in one quadrat of one hundri'd s(puire feet, k signifying 1 

 too; /;, 5' 10: r. lO-^-J."); r/. 2r)-r)(»: e. 50-100:/; 100-200: //. over 

 200: and o. none. These counts were estimated for the most 

 part, although care was taken to make actual counts at inter- 

 vals in order to avoid so far as possible any serious errors of ob- 

 servation. The (luadrats in this taidc, as wfdl as in all the oth- 



