Ixvi Trans. Acad. Sci. of St. Louis. 



February 1, 1897. 



President Gray in the chair, thirteen persons present. 



A philosophical paper by Mr. S. H. Emmens, which the 

 Council had ordered preserved in the library of the Academy, 

 was laid upon the table. 



Professor L. H. Pammel read a paper embodying ecolog- 

 ical notes on some Colorado plants, observing that botanists 

 who have studied the Rocky Mountain flora have frequently 

 commented on the interest attached to the plants from an 

 ecological standpoint, but most perplexing to the systematist. 

 It is not strange that this should be the case, since there are 

 great differences in altitude and soil, and the relative humidity 

 of the air varies greatly. This is a most prominent factor in 

 the development of plant life. A cursory glance at the plains 

 flora of eastern Colorado shows that there are representatives 

 of a flora common from Texas to British America and east 

 to Indiana. We should not for a moment suppose that 

 the species are identical in structure, since the conditions 

 under which they occur are so different. Attention was 

 called to the great abundance of plants disseminated by the 

 wind, as Cycloloma, /Salsola, Solanum rostratum, Populus, 

 Cercocaryus, " Fire-weeds " {Epilobium spicaium and Arnica 

 cordifolia)^ Hordemn juhatum, Elymus Sitanion^ etc. Plant 

 migration may be studied to better advantage in the irrigated 

 districts of the West than elsewhere, partly because the water 

 carries many seeds in a mechanical way, and partly because 

 the soil is very favorable for the development of plants. In- 

 stances were cited where several foreign weeds are becoming 

 abundant, as Tragopogon porrifolius and Lactuca Scariola. 

 The latter, known as an introduced plant for more than a 

 quarter of a century, is common at an altitude of 7,500 feet 

 in Clear Creek Canon. Once having become acclimated, it is 

 easy to see how Prickly Lettuce is widely disseminated. Col- 

 lectors appreciate the importance of giving more attention to 

 conditions under which plants thrive, such as phases of devel- 

 opment, soil, climate and altitudinal distribution. Structures 

 of plants are produced to meet certain conditions. Under 

 extreme conditions protective devices are more pronounced. 



