EUPHORBIACE^E. (SPURGE FAMILY.) 325 



Filaments united into a central column. Seeds subglobose, roughened or 

 reticulated, not carunculate. Erect herbs or undershrubs, with purplish 

 juice : leaves alternate, usually stipulate, entire (in ours). 



1. A. humilis, Miill. Stem about one foot high, much branched, silky 

 or strigose-pubescent, branches spreading : leaves narrowed at the base, spatu- 

 late or obovate-lanceolate or linear-lanceolate, acute, sparingly pubescent : 

 raceme much shorter than the leaves, on very short peduncles. S. Colorado 

 and southward. 



3. CROTON, L. 



Staminate calyx 4 to 6-parted. Petals often present, but small or rudi- 

 mentary, alternating with the glands of a central disk. Stamens 5 to 

 many, on a hairy receptacle. Pistillate calyx usually 5-parted, but the petals 

 mostly obsolete. Seeds smooth and shining, carunculate. Herbs or shrubs, 

 scurfy or stellately hairy or sometimes glandular : leaves alternate, entire or 

 repand. 



1. C. Texensis, Miill. Covered with a close canescent stellate pubes- 

 cence, dichotomously branched or spreading, 1 to 2 feet high : leaves lance- 

 ovate, oblong, or linear-lanceolate : dioecious ; racemes of staminate flowers 

 short : ovary stellate-tomentose ; styles twice or thrice dichotomously 2-parted. 

 S. Colorado and southward. 



4. EUPHORBIA, L. 



Flowers monoecious, included in 4 to 5-lobed involucres, the lobes usually 

 alternating with as many fleshy glands which are rounded or often petaloid- 

 margincd or crescent-shaped. Mostly herbs: leaves opposite or alternate or 

 the upper ones verticillate : involucres terminal or in the forks, the sterile 

 flowers lining the base and each from the axil of a little bract, the fertile 

 flower solitary in the middle of the involucre, soon protruded on a long 

 pedicel. 



A. Glands of the involucre with petal-like, usually white or rose-colored, entire or 



toothed margins or appendages. 



1. Leaves all similar, opjtosite, on short petioles, small, oblique at base, furnished 

 with awl-shaped or scaly and often fringed stipules: stems much branched, 

 spreading or usually procumbent : involucres solitary in the forks of the branches 

 or in terminal or lateral clusters, small, with 4 glands. 



* Seeds smooth and even: leaves entire, glabrous. 



1. E. pctaloidea, Engelm. Glabrous: stems procumbent or ascending: 

 leaves attenuate to the scarcely oblique base, oblong-linear or linear, retuse or 

 emarginate : involucres solitary, campanulate, lobes hairy beneath the glands 

 within, the broadly campanulate appendages conspicuous ; peduncles longer 

 than petioles : seeds reddish, with rounded angles. From Colorado to Ne- 

 braska and eastward to the Mississippi. 



2. E. flagelliformis, Engelm. Distinguished from the last by the 

 smaller involucre bearing very small and almost naked glands, often less than 



