228 UNIVERSITY OF COLORADO STUDIES 



which one would expect to find only on the arid plains, yet such sage 

 brush is found at even higher levels along the line of the Denver, Boulder 

 and Western Railroad near the Bluebird Mine in Boulder County a few 

 miles to the north of Tolland. This particular ridge at Tolland where 

 the sage brush grows is sheltered so that it easily becomes well warmed 

 and also it is quickly drained so that conditions are not very different 

 from what would be found on the "sage flats" along the Arkansas River 

 or elsewhere in the plains region. 



Grassland. — Bordering the streams and ponds of Boulder Park there 

 is usually a swampy zone formed by a growth of sedges, marsh grasses 

 and other bog or moor plants. This area is somewhat widened out in 

 some parts of the park especially around Park Lake and in other low-lying 

 situations. Scattered through this bog land there are often clumps of 

 willows which, in places, occupy so -much of the ground that a true 

 thicket is produced. In like manner an invasion of Potentilla may 

 result in the formation of a Potentilla scrub. Along the steep hillside 

 at the north of the park there is some of this moorland 1 which at certain 

 points is giving place to willows and alders, or to aspens; in other 

 places it is passing into meadow or else to dry grassland. 



What I have called meadow is a dense growth of grasses with some 

 sedges and generally a great abundance of flowering herbs. It is some- 

 what drier than the moor or Carex association but more moist than 

 the dry grassland. It is nearly always present as a distinct horizontal 

 belt or zone all along the bases of the small morainic hills east of Tolland. 

 It forms a like characteristic belt following old shore lines and benches 

 west of town. The meadows of Boulder Park might well be divided 

 into a number of societies, many species of plants being established in 

 particular parts of the meadow best suited to their growth. 



In the better-drained portions of the park there is a dry grassland 

 which forms a sparse earth-covering because the looseness of the soil 

 permits rapid drying out. Close grass mat such as seen in the meadow 

 does not exist here but certain sod-forming species of Carex produce a 

 rather thin carpet. The soil of the dry grassland is shown by study of 

 samples to have a low moisture content. 



1 The word "moor,'' a'though practically unknown in America, is a useful term to apply here in place 

 of "bog" or "swamps" which, to Europeans at least, have other and rather different meanings. 



