Delphinium Carolinianum and related Species 



By p. a. Rydberg 



None of our native larkspurs has been more misunderstood 

 than Ddphiiiiiun Carolinanuin Walt. , or D. azitreum Michx. This 

 species is found in the southern states only, its northwestern limit 

 being in Missouri. All specimens from the western states referred 

 to it belong to one of the other species described below. Any one 

 who has collected specimens of so-called D. aziireum in the prairie 

 states or in the Southwest has found trouble in trying to harmonize 

 the specimens collected with the descriptions in our manuals. 

 Some years ago I came to the opinion that the D. azureuin of Ne- 

 braska and neighboring states was quite different from the D. 

 azureiim of the South. It is only lately, however, that I have had 

 occasion to give closer attention to the matter, in connection 

 with a partial revision of the Ranunculaceae of Dr. Britton's Flora. 

 I have come to the conclusion that D. azureuin, as treated in Gray's 

 Synoptical Flora, contains about ten species. I regret that I have 

 not seen mature seeds of a few of the western species, as the seeds 

 afford excellent characters for determination. 



All the species treated here have a leafy stem and seeds with 

 a loose cellular coat, that becomes transversely rugose squamel- 

 late. The most prominent characters by which they may be dis- 

 tinguished from each other are the following : 



Bractlets some distance below the calyx and below the thickened portion of the pedicel. 

 Sepals deep blue ; principal segments of the leaves cuneate, cleft nearly or quite 

 to the middle. l- D- gerattiifolhtm. 



Sepals white, tinged with blue ; segments cleft beyond the middle into narrow 

 oblong or linear lobes. 

 Spur about twice as long as the petals ; sepals obovate. 

 Spur straight or slightly curved. 



Lobes of the lateral petals not diverging ; lower pedicels not much 



elongated; spur mostly horizontal. 2. D. albescens. 



Lobes of the lateral petals diverging ; lower pedicels elongated ; spur 

 mostly erect. 3- ^- camporum. 



Spur strongly curved upward. 4. D. Penardi. 



Spur thrice as long as the petals, slightly j-curved ; sepals oblong. 



5. D. macroseratilu. 



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