162 ILLINOIS STATE ACADEMY OF SCIENCE 



This is a condition which, in its total aspect, approxi- 

 mates rather closely the habitat of the barberry in the 

 Carpathian region, where, according to Pax (11), '*am 

 Waldrande imd an licteren St ell en des Hochwaldes er- 

 scheint ein charakteristisches Bnschwerk aiis Berberis 

 vulgaris'^ and other shrubs. A similar statement is 

 made by Pax at a later point (11. p. 257). This state- 

 ment implies an association with other shrubs in a simi- 

 lar habitat, which is readily substantiated in Illinois 

 through its association with the gooseberry {Ribes 

 grossularia Linn.) and the buckthorn {Rhamnus cathar- 

 tica Linn, and R. lanceolatus Pursli.) and the hawthorns 

 (Crataegus spp). 



That the presence of barberry in such shrub associa- 

 tions should be expected is evident from the fact that, in 

 the first place, forest soils otfer opportunity for growth 

 in that they have been thoroughly w^orked over hy their 

 worm inliabitants and in that the resulting rich aeration 

 of mould leads to the formation of highly oxidized neu- 

 tral substances so that acids may form as low a propor- 

 tion as one-sixteenth of the organic substance. 



The presence of primeval forest on any area must pre- 

 clude the possibility of shrub growths because of light 

 relations but, following the thinning of the forest and its 

 eventual destruction, the alteration of the light relations, 

 and of the soil through drying out and through the dying 

 off of its worm inhabitants, gives rise to a dry heath soil 

 where shrub growth may take place ■ under favorable 

 auspices. In fact, such an environment should prove al- 

 most ideal because (9. p. 542) the edaphic conditions of 

 the heath in cold-temperate belts give to shrub forma- 

 tions their most widely spread types. 



It may be argnied in contradiction to the foregoing that 

 the locations indicated on our maps present a sugges- 

 tion of the influence of lakes and rivers to the presence 

 of escaped barberries, but it should be remerabered that 

 there is to be expected an increasing luxuriance of for- 

 est formations near lakes and rivers where moisture 

 is increased l)y infiltration. It is noteworthy also that, 

 in the occurrence of escaped barberries near streams, 



