456 EUPHORBIACEA OF THE MEXICAN BOUNDARY 
1829), Thurber, Schott. Stem 3-1 foot high; leaves 12-18 lines long, 1-1} line broad ; margin revolute, and serra- 
tures thereby often invisible. Involucre with large bright white appendages, 3 lines in diameter. 
EUPHORBIA TRACHYSPERMA, 7. sp.: annua, erecta, glaberrima; foliis e basi subequali obtusa seu angustata 
oblongo-lanceolatis serratis mucronatis; stipulis filiformibus seu subulatis setaceo-fissis ; anthodiis alaribus demum in 
cymulas paucifloras terminales s. laterales confertis ; appendicibus angustis albis; stylis ultra medium bifidis ; capsula 
obtusangula; seminibus subcubicis faciebus leviusculis, angulis acutis crenatis asperatis. San Pedro; Sonora; 
Wright, No. 1832. Slender, erect, about 1 foot high, branches erect, few ; leaves 9-12 lines long, 2-3 lines broad ; 
seed 1 line long. 
EUPHORBIA EXSTIPULATA .: annua, erecto-patula, ramosa, glabriuscula seu minute sparsimque aspera ; 
foliis lanceolatis seu Ss asda naan argute serratis basi equali in petiolem brevem angustatis ; stipulis sabeinllls 
s. glanduliformibus; anthodiis alaribus solitariis; pedunculis petiolo brevioribus; appendicibus anticis plerumque 
2-lobatis, posticis majoribus 4-lobatis; stylis ovarium ad angulos scabrum equantibus, profunde bipartitis; stigmatibus 
filiformibus ; seminibus magnis subcubicis verrucosis et transverse 2-3-costatis. Western a Wright (1833 and 
1838). New Mexico; Fendler (No. 790). Sonora; Thurber, Bigelow, Parry. Stem about 6 inches high; leaves 
about 1 inch long, 1-2, rarely 3 lines wide, sometimes not absolutely apouatte, ha a little one: seed 1 liv long, 
with thick cross-ribs. A transition form to the next sections. 
§Il. ZYGOPHYLLA. 
EUPHORBIA HEXAGONA, Nutt. in Spreng. Syst. 3, p. 791. E. heterantha, Nutt. in Trans. Amer. Phil. Soc. [190] 
(n. ser.) 5, p. 173. Rio ae Texas ; Thurber. “Many years ago Mr. Nuttall gave me specimens of this - 
plant, named £. headinn: rt of these were sent to Sprengel, who first published a description of the species in the 
work quoted. Eight years shares Mr. N. described the plant under another name. It is remarkable for being 
polygamous ; most of the involucres containing only male flowers.” — Torrey, Mss. 
EUPHORBIA BILOBATA, 7. sp.: annua, erecta, gracilis; foliis oppositis breviter petiolatis lanceolato-linearibus 
acutatis integris glabriusculis, rameis angustioribus ; anthodiis alaribus campanulatis ; glandulis bilobis, appendiculis 
hinis lanceolatis seu abbreviatis ; stylis vix basi connatis ad anal bilobis ; sHiematibus erectis subteretibus ; capsula 
leviuscula, seminibus ovatis wcutis angulato-tuberculatis. Near the -Copper Misies, New Mexico; Bigelow. Eastern 
Sonora; Wright (No. 1831). Stems 6-15 inches a leaves ine lines long, 1-2 lines broad ; seeds 0.8 line long, 
strungly tuberculate and almost angular. Glan markable and very constant in shape ; appendages white. Near 
E. hexagona ; distinguished by the ares more site leaves, bilobed glands, terete stigmata, and smaller tuber- 
culate seeds. 
EUPHORBIA BIFURCATA, ». sp.: glabra; caule erecto dichotomo ; foliis oppositis ovatis seu obovatis in petio- 
Jem gracilem subequilongum angustatis argute serratis obtusis basi glanduloso stipulatis ; anthodiis alaribus brev- 
iter pedunculatis ; lobis 5 ovatis truncatis fimbriato-multifidis ; glandula singula cyathiformi late albo-appendiculata, 
appendice transverso emarginato; stylis basi coalitis ad medium bifidis, stigmatibus filiformibus. Moist places, 
Valley of the Limpio, July ; Bigelow. Over a foot high; leaves 1 inch long, $ inch wide; petiole a little shorter 
than leaf. 
§ Ill. CYATHOPHORA. 
EvrHorBia DENTATA, Miche.; 8. RIGIDA: humilior rigida; foliis parvis coriaceis reticulato-venosis scabris 
margine revolutis. Head of San Sin River; Wright (No. ay Near Monterey, Mexico; Dr. Edwards. 
y- CUPHOSPERMA : erecta, stricta, dentata seu parce pilosa ; foliis lanceolatis seu lineari-lanceolatis elongatis subdenta- 
tis; eapsulis glabris sen pilosis; seminibus majoribus naan ie ety Copper Mines, New Mexico; Wright 
(No. 1834), to Sonora; Schott. Ojo de Gabilari, Chihuahua; Thur 
EUPHORBIA acumaieenge Linn. (E. cyathophora, Murr.) Var. GRAMINIFOLIA: foliis angusto-linearibus. 
Crevices of rocks and dry beds of rivers. Rio San Pedro, Texas ; Bigelow, Schott, Wright (No. 653). South of El 
Paso ; Wright (No. 1835). 
EUPHORBIA BARBELLATA, n. sp.: annua, erecta, glabriuscula ; foliis sparsis linearibus seu lanceolato-linearibus 
sett ovatis lobatisque breviter petiolatis parce argute dentatis, subtus ad nervam medium parce pilosis, basi pilis longi- 
oribus confertis barbatis ; foliis floralibus ovatis seu e basi dilatata elongatis, basi roseis ; anthodiis glomeratis majus- 
culis ; glandula singula sessili lobis inciso-dentatis breviore; stylis brevibus erectis basi vix connatis ad medium bifidis. 
On the Rio Giande, near Eagle Pass; Wright. Rio Frio ; Bigelow. Near E. heterophylla, but stouter, leaves very 
sharply serrate, involucre larger, sere shorter. Leaves 2-4 inches long, 3 or 3 inch down to 1 or 2 lines wide. Beard 
of coarse hair at base of leaves very conspicuous. 
