556 Rydberg : Rocky Mountain flora 



to find two species that would produce a combination of characters 

 found in C. oreophilus. A mixture of four species, C. pulchellus, 

 C. spathulatus, C. scopulorum and C. coloradensis might do it. 

 I think therefore that it is best to regard it at present as distinct. 



Under Carduus bipinnatus (Eastw.) Heller, in the New Manual, 

 we find: C. pulchella[us], C. truncatus Greene (?) and C. spathulatus 

 Osterh. The only true synonym is C. truncatus Greene. C. 

 pulchellus is related to it, but the leaves are white-tomentose 

 beneath. C. spathulatus Osterhout is related to C. griseus, though 

 its involucral bracts are much shorter. The plant resembles 

 closely C. americanus, but the bracts are not at all fimbriate. 



Carduus Tracyi Rydb. is, in the New Manual, made a syn- 

 onym of C. Nelsonii Pammel (Pammel did not use the generic 

 name Carduus and the page is wrongly cited), while the latter is 

 kept distinct from C. plattensis Rydb. 



A botanist with broad limitations of species might regard 

 Carduus plattensis, C. Nelsonii, C. Tracyi, C. brevifolius, and C. 

 palousensis as one species. They are all closely related but each 

 has a definite range of its own. C. plattensis belongs to the sandy 

 regions of Nebraska, Kansas, and northeastern Colorado; C. 

 Nelsonii, as far as I know, is found only in Wyoming; C. Tracyi 

 in southern Colorado ; C. brevifolius in Wyoming and Montana ; and 

 C. palousensis in western Idaho and eastern Washington and 

 Oregon. Carduus Nelsonii and C. plattensis are the most closely- 

 related of the four; the only difference I can find is that C. plattensis 

 has the inner bracts prolonged into linear lanceolate, spreading, 

 more or less crisp tip, a character not found in the rest. The 

 characters given by Nelson in the key to distinguish C. Nelsonii 

 and C. plattensis are useless, because the characters assigned to 

 the latter are not true. 



Under Carduus filipendulus (Engelm.) Rydb., in Coulter & 

 Nelson's New Manual, are given as synonyms: C. Flodmanii 

 Rydb. and C. oblanceolatus Rydb. The description of C. 

 filipendulus is a verbatim copy of my description of C. 

 Flodmannii. Little could be said against this, if the two 

 were the same, but this is not the case. In the key, Professor 

 Nelson distinguishes C. filipendulus from C. undulatus, C. mega- 

 cephalus, and C. ochrocentrus by the characters: "Leaves becoming 



