178 UNIVERSITY OF COLORADO STUDIES 



tributaries from the north and south. It carries the waters, to the 

 South Platte River about five miles to the west. In the summer there 

 is very little water in the streams. Eastward, above the town, is Flor- 

 issant canyon, through which the main creek flows. 



In following up any of the tributaries of Florissant Creek^ there 

 wiU be found places with a considerable accumulation of humus soil 

 and a plant covering of mesophytic^ character. Here and there are 

 stretches of boggy ground where hydrophytes^ find a suitable sub- 

 stratum. But if we take it all in all, we find a dry-country vegeta- 

 tion throughout the Florissant district. 



A botanist does not need to be told that the town of Florissant has 

 been in existence for some years. The weeds along the railroad track 

 and in the roadways and through the pastures tell the story. A con- 

 siderable number of these weeds have been introduced from lower 

 altitudes since the settling of the country by man. Various plants 

 of the aster, mustard, spurge, smart-weed, and grass families are espe- 

 cially conspicuous as roadside weeds. 



An examination of the plant population of the Florissant region 

 shows a great number of plants of the aster or composite family. In 

 fact, during midsummer the prevailing color of the landscape is greenish 

 yellow, due to the many coarse composites which are coming into 

 blossom at that time.'* A great preponderance of composites is to 

 be noted throughout Colorado, but especially in the south. 



» Otherwise known as Twin Creek. 



> ficVot, "middle;" i^i'toi', "plant;" i. e., plants growing in conditions of medium dryness. 

 3 vSutp, "water;" ^vtov, "plant." 



« The following plants of the composite family were collected. DeterminatioDs were made by Professor 

 Aven Nelson. 



AchUlaea lanulosa Nutt. Helianthella parryi A. Gray 



Anlennaria parvijolia Nutt. Helianthus peiiolaris Nutt. 



Artemisia borealis Pall. Lygodesmia juncea (Pursh) D. Don. 



Artemesia canadensis Michx. Machaeranthera varians Greene 



Artemisia frigida Willd. Picradenia floribunda ulilis Ckll. 



Carduus acaidesccns (A. Gray) Rydb. Picradenia ligulaeflora Aven Nelson 



Carduus ochrocenlrus (A. Gray) Greene. Rudbeckia flava Moore 



Chaenactis douglassii (Hook.) H. & A. Senecio bigelovii A. Gray 



Chrysopsis resinnlens Aven Nelson. Senecio eremophilus Richards. 



Chrysothamnus sp. Senecio spartioides T. & G. 



Crepis runcinata (James) T. & G. Solidago decumbens Greene ^ ' 



Erigeron canus A. Gray Solidago missouriensis Nutt. 



Erigeron sp. 



