OF ARTS AND SCIENCES. 171 



the San Pedro River in Arizona,, under the name of E. micromera, in 

 DC. Prod, ined., by the very small involucres (0.2 lines long), the 

 entire absence of appendages on the small yellow, not purple, glands, 

 and the extremely short styles with subglobose stigmas. The length 

 of the styles in these Euphorhice, however, is not a very safe character, 

 as this specimen from San Lucas, and some . others from Arizona and 

 the Colorado desert prove : they have suberect styles shorter than the 

 ovary (only about ^ line long), while most forms from the State of Cali- 

 fornia have elongated styles with divaricate clavate branches, twice as 

 long as the ovary. My remarks about the variability of the plant may 

 be extended to the shape of the leaves, which are usually oval, oblong, 

 or oblong-linear, and obtuse at the base, but in specimens collected by 

 Dr. Newberry at Laguna I find them almost orbicular and deeply cor- 

 date at the base. The stipules are divided on the upper, and united 

 on the lower side of the stem, lanceolate-subulate, mostly entire and 

 ciliate, in the specimen from San Lucas, however, glabrous. Stem and 

 leaves usually glabrous, sometimes with a few scattered hairs, or entirely 

 pubescent. The pubescent forms have always very narrow appendages, 

 and the pubescence extends even to the ovary and capsule. The seeds 

 are 0.4 line long, sharp-angled, with the sides almost smooth, or usually 

 more or less distinctly undulate. 



110. "Euphorbia hypericifolia, Linn., var. communis, Engelm. 

 in Bot. Mex. Bound, p. 188. E. Preslii, Gussone Fl. Sicul. 1, p. 531 ; 

 Boiss. in DC. Prod. ined. — Boissier's weighty authority has not con- 

 vinced me that the Linnsean E. hypericifolia, with smaller flower- 

 heads, smaller capsules, and smaller and paler seeds, is distinct from 

 our common northern var. communis. This latter has become natural- 

 ized in Italy, where it has been described under different names (^E. 

 androscemifolia, Presl, E. trinervis, Bertol., and E. Preslii, Guss.) ; 

 nor can I distinguish E. lasiocarpa, Klotzsch, from the West Indies 

 and South America, by any character besides the pubescent capsules. 

 Intermediate forms unite all these forms. 



111. "Euphorbia gymnoclada (sp. nov.) : fruticosa? ramis basi 

 lignescentibus teretibus gracilibus strictis glabratis ; foliis rameis terna- 

 tis internodio elongate multoties brevioribus linearibus seu oblanceolato- 

 linearibus integris carnosulis (siccitate conduplicatis) subtus puberulis 

 supra subnudis in petiolum brevissimum attenuatis ; cymae terminalis 

 umbelliformis puberulse radiis ternis iteratim dichotomis ; pedicellis 

 bracteas anguste lineares et involucra magna asquantibus; involucri 



