028 MINNESOTA BOTANICAL STUDIES. 



trees that had grown scattered amongst the weeds were found 

 to have been fire-killed, but about one-half of their number had 

 grown out again near the ground. The larger ones in the south 

 corner had not been killed, because there the weeds had not 

 (jrown as thick. 



O 



Patches of the perennials, Elytnus canadensis and a few other 

 grasses, as well as goldenrods, sunflowers and nettle were coming 

 out vigorously. The rice cut-grass, however, although it seems 

 to be perennial, had a very poor start. On close examination 

 numerous seedlings of annuals were found, but all looked 

 brownish and sickly on account of the dry weather and the 

 glaring sunlight. Although most of them were not readily 

 identified, I recognized the following without difficulty : 



1. Polygonum sp. 



2. Mentha sp. 



3. Carduus lanceolatus, the seedlings of which looked quite 

 green and vigorous. 



4. Lactuca sp. 



5. Brassica nigra. 



6. Ckenopodium sp. 



The spring and summer of 1899 were excessively dry in this 

 region so that, since January ist a continued accumulated defi- 

 ciency of rain of over 4 inches was reported from May 3ist 

 to August 3ist. About June loth another new factor, one that 

 is able to destroy all plant life not perennial or not armed in 

 some way, appeared on the scene cattle, a large herd of 

 hungry dairy cows. In their search for green grass they had 

 passed over the dried-up marsh and along at the foot of the 

 embankment and had discovered the East section of Trestle 

 island. 



In the end, however, bovine instinct for plant selection proved 

 of some interest, for, when after an absence of over two months, 

 I visited the place again about Sept. loth, there was a closely 

 cropped, rough, much trampled piece of pasture. Where a 

 year ago about 60 different plants had grown in wild exuber- 

 ance, only about 40 cropped and crippled trampled species were 

 to be found* and only a single one of these bloomed and flour- 

 ished in large numbers, the formidable armed thistle, Carduus 



* About 30 species of the list of August 16, 1899, had survived fire and cattle 

 and about 10 species were found that do not appear on the list of August 16, 

 180.0. 



