^ OF ARTS AND SCIENCES. 295 



§ 4. Vulgares : procumbentes vel adscendentes : articuli plerumque 



minores : aculei validi, subteretes vel nulli, albidi vel obscuriores : 



bacca clavata. 



16. O. Rafinesquii, E. in P. R. R. : diffusa ; radice fibrosa ; articulis 

 obovatis vel suborbiculatis perviridibus, foliis elongatis patulis ; pulvil- 

 lis subremotis setas graciles rufas gerentibus plerisque inermibus ; 

 aculeis paucis marginalibus validis rectis singulis erectis patulisve, uno 

 alterove minore deflexo subinde adjecto, rufo variegatis ; alabastro 

 acuto ; ovario clavato pulvillis 20-25 stipato ; petalis 10-12; stig- 

 matibus 7 - 8 ; bacca clavata. 



Var. MICROSPERMA : subinermis : seminibus minoribus angustius 

 marginatis. 



Sterile, sandy, or rocky soil in the Mississippi valley, from Kentucky 

 to Missouri, and from Minnesota southward : fl. May and June. — 

 Joints 3 - 5 inches long ; leaves 3-4 lines long; spines 9-12 lines 

 long, sometimes entirely wanting. Flowers 2J--34- inches in diame- 

 ter, yellow, often with a red centre. Seed 2^ lines, or in the variety 

 less than 2 lines in diameter. — This species had been confounded 

 with the Eastern 0. vulgaris by all our botanists, with the exception 

 of Rafinesque, who pretended to distinguish three species, viz. O. hu- 

 7nifusa, 0. ccBspitosa, and 0. mesacantha (sometimes erroneously 

 accredited to Nuttall), which cannot be made out, and which I have 

 ao-ain united under their author's name. — The following is probably 

 only a Southern variety of this species : — 



O. GRANDiFLORA, E. : subadsccndens ; articulis majusculis ; pulvillis 

 remotis ; setis tenuissimis; aculeis subnuUis ; floris grandis ovario 

 elongate; petalis sub-10 latissimis ; stigmatibus 5; bacca elongata 

 clavata. 



On the Brazos, Texas. — Joints often 5-6 inches long; pulvilli 

 nearly an inch apart. Flowers 4^-5 inches in diameter, red in the 

 centre ; petals 2 inches long or more, and IJ- wide. 



Dr. Biselow collected on his tour from Arkansas to Santa Fe sev- 

 eral forms, which, though somewhat distinct, are perhaps not entitled 

 to be considered species. The true 0. Rafinesquii does not seem to 

 occur west of the western line of Missouri and Arkansas. The West- 

 ern forms or subspecies are : — 



O. CYMOCHiLA, E. & B. in P. R. R. : diffusa ; articulis orbiculatis ; 

 pulvillis subremotis stramineo- seu fulvo-setosis plerisque armatis ; acu- 

 leis 1-3 robustioribus albidis basi fulvis patentibus deflexisve, additis 



