48ti (JXXl. EUPHORBlACEiE. Euphorbia. 



Ctmspedus of the Genera. 



i Fruit in a toothed, leafy involucre. Acalypha. a 



IS — 16-androus. cl'i'uit not involuciate. Crolo/i. 5 



poljandious. Leavus large, glaucous, fieltate. Ricimis. 3 



tetrandrous. ■ Leaves evergreen, ov te Buxus. 7 



pentandrous. Leaves clbihed with shining scales. Crotonopsis. i 



triandrous. Leaves very small Phyllanthus. 6 



monaiidrous, several in a corolla-like involucre. ..... Euphorbia. 1 



1. EUPHORBIA. 



Euphoihus, physician to Juba, khig of Mauritiana, first used these plants in medicine. 



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

 campannlate, with 4 — 5 petaloid segments alternating with as many 

 external, gland-like teeth, d^ 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 Jlowers in involucrate umbels, f Cauline leaves alter ?i.ate. 



1. E. coROLLATA. Flovxriug Spurge. 



Erect; cauline and floral lvs. oblong, narrow, obtuse; ijiner segments of tlie 

 invol. obovate, petaloid ; urnhcl 5-rayed, ray.s 3 or 3 times di- or trichotomous. — 

 1|. 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 lvs. obovate, cauline wedge-form, serrate, smooth ; umbel 5- 

 rayed, then 3-rayed and forked. — ® A milky weed in cultivated grounds, JS". 

 H. ! to Niagara 1 S. to Car., 'remarkable for the symmetry of its vegetation. 

 Stem smooth, erect, 8 — IC high. Leaves scattered, § — lA' 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, Julj^ 



' 3. E. NEMORALis. Darl. (E. pilosa. Pursh.) Hairy Spurge. 

 i>eaTCS"ob]ong-lanceolate and oblanceolate, acute, "narrowed to the base, 

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

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

 verrucose. — % 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 ; lvs. alternate, sessile, spaj:ulate, serrulate, smooth ; umbel 3-rayed, 

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

 muricate. — % Grows in waste grounds, Can. to Va. Stem 12 — 18' high. 



5. E. Peplus. 



5'^. erect or ascending, branched below; umbels 3-rayed, raA-s mostly di- 

 chotomous ; involucrate /w. ovate, acute. — (J) A small species, 'in cultivated 

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

 + Cauline leaves opposite. 



6. E. Mercurialina. Muhl. 



St. weak and slender, simjjly 3-cleft ; lvs. opposite and ternately verti- 



