386 euphokbiacejE. (spurge family.) 



glands at its sinuses. Sterile flowere numerous and lining the base of the invo- 

 lucre, each from the axil of a little bract, and consisting merely of a single sta- 

 men jointed on a pedicel like the filament: anther-cells globular, separate. 

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

 pedicel, consistmg of a 3-lobed and 3-celled ovary with no calyx, or a mere ves- 

 tige. Styles 3, each 2-cleft; the stigmas therefore 6. Pod separating into 3 

 one-seeded carpels, which split elastically into 2 valves. Seed often carnncled. 

 — Plants (herbs in the United States), with a milky acrid juice, the upijcrmost 

 leaves often in whorls or pairs. Peduncles lateral or terminal, often umbellate- 

 clustered. (Named after Euphorbus, physician to King Juba.) 

 For the following elaboration of the genus I am indebted to Dr. Engelmann. 



§ 1 . Leaves {all opposite and similar^ small) furnished with awl-shaped or scaly stip- 

 ules : stems much branched : involucres solitary in the Jbrks or axils, sometiiiu'S 

 crowded or clustered on the branchlets ; root annual in all our species ; plants flower- 

 ing all the summer and autumn. (Stipulatae.) 



* Seeds smooth and even, ash~colored : leaves entire, glabrous, as is the whok plant, 

 and pale or slightly glaucous. 



1. E. polygonifolia, L. (Shore Spurge.) Prostrate-spreading; 

 leaves oblong-linear, obtuse, mucrouate, slightly cordate or obtuse at the oblique 

 base (4" - 8" long) ; peduncles equalling tlie short petioles ; glands of the invo- 

 lucre minute, not appendaged; pod obtusely angled; seeds ovate (1" long, the 

 largest of this section). — Sandy shore of the Atlantic and of the Great Lakes. 



2. E. Geyeri, Engelm. Procumbent ; leaves oblong-ovate, obtuse at the 

 apex and the oblique base ; peduncles equalling the petioles ; appendages of the 

 involucre petal-like {white), orbicular ; pod acutely angled ; seeds obtusely tri- 

 angular (J" long). — Sandy soil, Beardstown, Illinois ( Geyer), and soutliwest- 

 ward. — This is a small-seeded form (var. microsperma) : other forms in Mis- 

 souri and Texas have larger petal-like appendages and larger seeds. 



3. E. lierniarioides, Nutt. Prostrate ; leaves round-ovate, obtuse at 

 the base (only J"-2J" long) ; peduncles much longer than the petioles, lateral, sin- 

 gle or clustered ; appendages of the involucre minute and crenulate, or none ; pod 

 acutely angled; seeds obtusely angled (|" long). — Banks of the Mississippi 

 and lower Ohio, in rich alluvial soil, and southwestward. 



# * Seeds minutely roughened, ash-colored: leaves serrulate, hairy. 



4. E. hlimistriita, Engelm. mss. Procumbent, puhorulent or hairy ; 

 leaves elliptical with an oblique obtuse base, serrulate towards the apex, sparse- 

 ly hairy underneath (J'- 1' long, sometimes with a brown spot above) ; pedun- 

 cles rather shorter than the petioles, crowded in lateral clusters ; involucre cleft 

 on the back, its appendages orbicular or truncate and nearly entire ; pod acute- 

 ly angled, puberulent ; seeds ovate, 4-angled (|" long). — With the last. 

 — Branches 6' -20' long. Distinguished from .the next by its broader leaves, 

 slit involucre, and rounder, granulated (not transversely grooved) seed. 



* * ^ * Seeds transversely umnkled-pitted ; leaves serrate, often hairy and. falcate. 



5. E. maculata, L. (Spotted Spurge.) Prostrate; leaves very 

 oblique at the base, oblong-linear (4" -6" long), serrulate towards the apex 



