i9"] NELSON— IDAHO PLANTS 



J 45 



subulate, 4-5 mm. long in fruit: corolla not seen: nutlets 4, about 

 2 mm. long, narrowly conical, attached their whole length by an 

 open but narrow groove to a slender-subulate gynobase, the small 



areola at base scarcely forked, closely muricate with silvery-gray 

 spinellae on a brown background. 



Material in this genus is assigned with difficulty. Floral characters give 

 but little clue. Aspect and the nutlets are the most reliable characters. Even 

 these seem to vary much, but after making due allowance for this fact, the 

 present specimens cannot be referred to C. multicaulis A. Nels., Bot. Gaz. 

 3° : *94> nor to C. grisea Greene, Pitt. 5:53, apparently the two nearest allies. 

 Both of these differ essentially as to the nutlets. 



The type is Nelson and Macbride's no. 131 1, from sagebrush plains, near 

 Minidoka, July 24, 191 1. 



Pentstemon confertus Dough— Perhaps in no group of 

 Pentstemon does a tendency to vary with every change in the 

 ecological conditions manifest itself so fully as in P. confertus and 

 its allies. In this group there are three rather strongly marked 

 species: P. attenuates, P. confertus, and P. procerus, all by Doug- 

 las. In recent years several others have been added, some as 

 species and some merely as varieties. How many of these should 

 stand may not yet be said, but certainly not all of them. The 

 undue multiplication of species might be held measurably in check 

 if we could reach some agreement as to the relative importance of 

 the characters ordinarily relied upon in describing these plants. 

 The diagnostic characters mostly used are (1) pubescence in corolla 

 throat and on the sterile filament, (2) shape and size of the corolla 

 and the calyx lobes, (3) glandulosity of the inflorescence, (4) 

 pubescence on the herbage, (5) color of the corolla. Now it is 

 evident that if one phytographer considers one of these as of funda- 

 mental value in determining relationship, and another takes one 

 of the other characters as basic, and a third still another, and so on, 

 the number of species that may be described by the rearrangement 

 of these characters becomes merely a problem in permutation. 

 It seems, therefore, that one ought to place first those characters 

 which are probably modified the least by reason of a change of 

 environment, that is, those characters which are fundamentally 

 concerned with the perpetuation of the species should stand first 

 and the others should be serially arranged in the order in which they 



