486 CXXI. EUPHORBIACE^E. EUPHORBIA. 



Conspectus of the Genera. 



\ Fruit in a toothed, leafy involucre. Acalypha. 2 



8 16-androus. (. Fruit not involucrate Croton. 5 



polyandrous. Leaves large, glaucous, peltate. < Ricinus. 3 



tetrandrous. Leaves evergreen, ovate. . Buxus. 7 



pentandrous. Leaves clothed with shining scales. Crotonopsis. 4 



triandrous. Leaves very small Phyllanthus. 6 



Sierilefls. monandrous, several in a corolla-like involucre. ... . - . Euphorbia. 1 



1. EUPHORBIA. 



Euphorias, physician to Juba, king of Mauritiana, first used these plants in medicine. 



Flowers c? , mostly achlamydeous ; involucre monophyllous, sub- 

 campanulate, with 4 5 petaloid segments alternating with as many 

 external, gland-like teeth. cT 12 or more ; stamen 1 ; filament articu- 

 lated in the middle. 9 solitary, central ; ovary pedicellate ; styles 

 3, bifid ; capsule 3-lobed, 3-celled ; cells 1 -seeded. Herbs or shrubs, 

 with a milky juice. Lvs. generally opposite, sometimes wanting, often 

 stipulate. Invol. axillary or subumbellate. 



* Heads of flowers in involucrate umbels, f Cauline leaves alternate. 



1. E. COROLLATA. Flowering Spurge. 



Erect; cauline and floral Ivs. oblong, narrow, obtuse; inner segments of tht 

 Invol. obovate, petaloid ; umbel 5-rayed, rays 2 or 3 times di- or trichotomous. 

 Qj. In dry fields, &c., Can. and U. S. Stem slender, erect, 1 2f high, generally 

 simple and smooth. Leaves 1 2' long, often quite linear, very entire, scat- 

 tered on the stem, verticillate and opposite in the umbel. The umbel, as in 

 other species, consists of about 5 verticillate branches from the summit of the 

 stem, each of which is subdivided into about 3, and finally into 2 peduncles. 

 Corolla-like involucre large, white, showy. July Aug. The central head is 



2 or 3 weeks earliest. 



2. E. HELIOSCOPIA. Sun Spurge. 



Erect ; floral Ivs. obovate, cauline wedge-form, serrate, smooth ; umbel 5- 

 rayed, then 3-rayed and forked. A milky weed in cultivated grounds, N. 

 EL ! to Niagara ! S. to Car., remarkable for the symmetry of its vegetation. 

 Stem smooth, erect, 8 16' high. Leaves scattered, f 1J' long, | as broad at 

 the rounded or retuse apex, finely and sharply serrate, entire, and tapering to 

 the base. Umbels subtended by a large involucre of 5 obovate leaves. Each 

 of the 5 rays is pilose with scattered hairs and subdivided into an umbellet of 



3 rays with a 3-leaved involucel, and these finally into 2 or more pedicellate 

 fascicles. Capsules smooth. June, July. 



3. E. NEMORALIS. Darl. (E. pilosa. Pursh.} Hairy Spurge. 



Leaves oblong-lanceolate and oblanceolate, acute, narrowed to the base, 

 subsessile, pilose beneath, those of the involucre ovate; umbel 5 8-rayed, rays 

 ones or twice divided; seg. of the floral invol. colored, entire, subreniform; ova. 

 verrucose. 1\. Moist woods, Can. to Va. Stem 2 3f high, smooth, rarely 

 branched below the umbel. Leaves 3 4' by 1', entire or slightly serrulate 

 above, those of the stem alternate, of the branches opposite and nearly as broad 

 as long. Floral involucre purplish-brown within. Capsule at length nearly 

 smooth. May, June. 



4. E. OBTUSATA. Pursh. Obtuse-leaved Spurge. 



Erect ; Ivs. alternate, sessile, spatulate, serrulate, smooth ; umbel 3-rayed, 

 rays twice dichotomous ; floral Ivs. ovate, subcordate, somewhat obtuse ; caps. 

 muricate. 1\. Grows in waste grounds, Can. to Va. Stem 12 18' high. 



5. E. PEPLUS. 



St. erect or ascending, branched below ; umbels 3-rayed, rays mostly di- 

 chotomous ; involucrate Ivs. ovate, acute. (f) A small species, in cultivated 

 grounds, Penn. to Va. Floral leaves large. Flowers conspicuous. Torr. 

 t Cauline leaves opposite. 



6. E. MERCURULINA. Muhl. 



St. weak and slender, simply 3-cleft ; Irs. opposite and ternately verti- 



