386 EUPHORBIACE^. (SPURGE FAMILY.) 



b 



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

 Iucre, 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, consisting of a 3-lobed and 3-cclled 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 caruncled. 



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

 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. 



4 1. Leaves (all opposite and similar, small) furnished with awl-shaped or scaly stip- 

 ules: stems much branched: involucres solitary in the forks or axils, sometimes 

 crowded or cluster* d on tin branchh is : root annual in all our species : plants flower- 

 ing all the summer ami autumn. (Stipulate.) 



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



and pale or slightly glaucous. 



1. E. p»Iygossif«>iia, L. (Shore Spurge.) Prostrate-spreading; 

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

 base (4"- 8" long) ; peduncles equalling the short petioles; (funds 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. Gfiyeri, 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 (V Ion-). — Sandy soil, Eeardstown, Illinois (Geyer), and southwest- 

 W ard. — 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. BiersssariOiilcs, Nutt. Prostrate ; leaves round-ovate, obtuse at 

 the base (only ^"-2i" 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. laiiStllstraSa, Engelm. mss. Procumbent, puberulent or hairy ; 

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

 ly hairy underneath (£'-$' 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 wrinkled-pitted: leaves serrate, often hairy and falcate. 



5. E. Msactil-tfa, L. (Spotted Spurge.) Prcstrate; leaves xvvy 

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



