SCIENTIFIC EXPEDITION TO NORTHWESTERN COLORADO 



"7 



Vegetation of streamside and bottom-lands. — From a ridge crest 

 the courses of the Grand and White rivers may be followed for miles by 

 the presence of cottonwoods which fringe them on both sides (Fig. n). 

 The narrowleaf cottonwood is the dominant tree along the largest 

 streams. The western cottonwood (Populus sargentii) and the lanceleaf 

 cottonwood were not seen. Only one tree of Wislizenus' cottonwood was 

 seen and that along Dry Elk Creek between Rifle Gap and Rio Blanco 

 Stage Station. This species is southern in its distribution, but extends to 

 higher latitudes west of the continental divide than east. Narrowleaf 

 cottonwoods were quite commonly overgrown with clematis in bloom. 

 Streamside birch, alder, choke-cherry, skunk-bush, willows and thorn- 

 apples form an undergrowth of shrubs along the streams. Buffalo 

 berry, a small thorny tree with silvery leaves and bright red berries, 

 grows in clumps in moist river bottoms. It also occurs along fences of 

 irrigated fields. Abundant and conspicuous herbaceous plants of 

 streamsides and bottom-lands are Rudbeckia ampla, Lactuca pulchella, 

 Helianthus nuttalli, Solidago canadensis, Aster adscendens and Gymno- 

 lomia multiflora. Hops climb and trail among the shrubbery. It is 

 noticed that the conspicuous flowering plants of streamside and bottom- 

 lands are composites. This is the case in all situations. The lower 

 altitudes throughout Colorado have a late summer and autumn vegeta- 

 tion which is characterized by the blooming of composites. 



Collection of Plants from Streamside and Bottom-Lands 1 



Typha latifolia L. 



Equisetum laevigatum R. Br. 



Equisetum pratense Ehrh. 



Triglochin palustris L. (half-submersed) 



Beckmannia erucaeformis (L.) Host. 



Chaetochloa viridis (L.) Scribn. 



Alopecurus aristulatus Michx. 



Deschampsia caespitosa (L.) Beauv. 



Elymus canadensis L. 



Elymus condensatus Presl. 



Hordeum jubatum L. 



Carex utriculata Boott. 



Eleocharis palustris (L.) R. & S. 



Scirpus lacustris L. 



Lemna minor L. (floating) 



Juncus bttjonius L. 



J uncus nodosus L. 



Vagnera stellata L. 



Populus angustifolia James 



Salix spp. 



Alnus tenuifolia Nutt. 



Betula jontinalis Sarg. 



1 The writer is under obligation to Professor Aven Nelson, of the University of Wyoming, who kindly 

 determined most of the specimens in this and succeeding lists. 



