THE PLANT WORLD 209 



"pace that kills," but into harmony with a changing environment. 



On our cold, arid x>lateaus we see the same conditions and the same 

 processes and results. The examples maj^ be less striking, but even 

 here the forms that survive have had many a sharp lesson. 



But no more striking example can be given than is exhibited in 

 some of the interior deserts, the Red Desert of Wyoming, for example, 

 where not the shortness of the season but the scarcity of water is the 

 prime cause of the noticeable haste. In such localities the moisture 

 that falls is principally the snows of late spring. These on melting 

 furnish the water which must carry many of these desert forms to full 

 fruition. The cloudless skies of June bring to maturity many small 

 annuals that spring into life in cool but moist May. More numerous 

 perennials scatter far and wide their abundant fruitage before July's 

 sun bakes completely dry valley, hill and plain. These latter have 

 adopted the storage plan as the best means of securing the requisite 

 speed when the favorable season comes. Rhizomes, bulbs, tubers and 

 roots, often enormous, are packed full of food materials which are con- 

 verted into immediately available funds to meet the heavy drafts that 

 the rush season demands. 



There is perhaps no class of plants that have learned the art of 

 hurrying so well as the generally despised weeds. A cockle-bur and a 

 pigweed rarely fail to mature some seed. Cut them off near the ground 

 repeatedly during the summer, and each time they will put out new 

 branches from the stump. These may in turn be destroyed, till as 

 Autumn approaches you forget about them, but they do not forget their 

 business. When the season closes a few prostrate branches will be 

 found with mature fruit. 



That plants, like most people, will not hurry except from neces- 

 sity, was abundantly in evidence during the field work of the past sea- 

 son. The identical species (various Eriogonums, Senecios, Solidagos 

 and many others), that were in full bloom on the higher plains of more 

 northern Wyoming in late July or early August, had reached only the 

 same stage of development by the first of September, in middle Colo- 

 rado and southward. Tlie contrast was all the more striking, since the 

 Colorado season opens two or three weeks earlier as well as closes as 

 much later. 



University of Wyoming, Laramie, Wyoming. 



