PLANT DEVELOPMENT 



The average dates of various developmental stages for 23 forbs and five grasses 

 growing on the southwest exposure at 7,100 ft. elevation are shown in figures 1 and 2. 

 The beginning of annual herbaceous growth for the 23 forbs spread over more than 3 weeks. 

 Lomatium generally was the first plant to begin growth (April 27) and Lupinus the last 

 (May 22). Usually, all five of the grasses studied began to grow during the first week 

 in May. 



The greatest difference between years for the beginning of growth was as much as 

 32 days for Linum and as few as 13 days for Lupinus (table 1). For most species this 

 difference was from 16 to 24 days, and averaged 20 days (tables 1 and 2). In other 

 words, the general start of plant growth varied approximately 3 weeks in just one 5-year 

 period. A much greater yearly variation (45 days for grasses and 50 days for forbs) 

 was recorded by Costello and Price (1939) over a 10-year period on mountain herblands 

 in Utah. 



The onset of flowering of the 23 forbs spread over more than 10 weeks (fig. 1). 

 These forbs can be categorized according to when they reach full bloom as early, middle, 

 or late season bloomers. The early bloomers are the first six species that generally 

 reach full bloom sometime in May. The next six species, the middle season bloomers, 

 reach full bloom in June, and the remaining species, the late season bloomers, usually 

 do not reach full flower until sometime in July. The flowers of Lomatium, Anemone, 

 Besseya, and Fritillaria are among the first signs that spring has finally arrived on 

 these mountain grasslands, while the flowers of Aahillea , Gaillardia, and Campanula are 

 a warning that the annual floral display will soon end. The grasses ordinarily flower 

 in mid-July; approximately 1 week elapses between the onset of flowering in the 

 earliest, Danthonia, and the latest, Agropyron (fig. 2). 



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