The maximum difference between years in date of drying of various species ranged 

 from 10 to 51 days. Generally, the later a plant flowered, the greater the difference 

 in date of drying between years. The average difference between the earliest and latest 

 drying dates was 19 days for early bloomers, 29 days for midseason bloomers, 33 days 

 for late bloomers, and 39 days for the grasses. 



The average length of time that plants remained photosynthetically active ranged 

 from 62 days for Dodeaatheon to 147 days for Danthonia (table 3) . This active period 

 was considered to extend from the onset of spring growth until the species dried. A 

 general relationship existed between time of flowering and the length of time that 

 plants remained active: early bloomers, 86 days; midseason bloomers, 94 days; late 

 bloomers, 115 days; the early-flowering Anemone, midseasonal Delphinium, and late 

 Lupinus were conspicuous exceptions to this generality (table 3). The grasses remained 

 active for by far the longest period (an average of 137 days) . Active growth for all 

 forbs and grasses averaged 108 days. 



Table 3 . - -Shortest , longest, and mean periods (in days) of photo synthetic activity over 5 years 



for plants on the southwest exposure at 7,100 ft. 



Species \ 



Shortest \ 



Longest ' 



Mean 



Species 



Shortest 



Longest ' 



Mean 



Dodeaatheon con jug ens 



50 



76 



62 



Campanula rotundi folia 



76 



127 



110 



Delphinium bioolor 



71 



89 



79 



Geum triflorum 



98 



131 



115 



Fritillaria pudiaa 



66 



102 



80 



Anemone patens 



105 



126 



116 



Saxifraga montanensis 



74 



93 



80 



Galium boreale 



111 



127 



118 



Agoseris glauoa 



72 



98 



81 



Achillea millefolium 



101 



150 



124 



Lomatium aous 



77 



95 



84 



Koeleria cristata 



96 



159 



127 



Polygonum bistortoides 



81 



97 



84 



Oxytropis serioea 



101 



152 



128 



Zygadenus venenosus 



69 



107 



92 



Comandra umbellata 



118 



140 



132 



Cerastium arvense 



83 



127 



95 



Agropyron spicatum 



131 



151 



135 



Besseya wyomingensis 



91 



99 



95 



Linum lewisii 



117 



146 



138 



Lupinus sereaius 



90 



108 



99 



Festuca idahoensis 



120 



169 



138 



Gaillardia aristata 



86 



123 



104 



Stipa ocoidentalis 



111 



160 



139 



Pediaularis contorta 



93 



121 



106 



Danthonia intermedia 



130 



164 



147 



Frasera speaiosa 



99 



122 



no 











11 



