196 COMMON CANADIAN WILD PLANTS. 



1. EIIPHOR'BIA, L. SpUBGE. 

 Flowers monoecious, the sterile and fertile ones both des- 

 titute of calyx and corolla, hut both contained in the same 4-5- 

 lobed cup-shaped involucre which resewibles a calyx, and there- 

 fore the whole will probably at first sight be taken for a 

 single flower. Sterile flowers numerous, each of a single 

 nahed stamen from the axil of a minute bract, Fertile 

 flower only 1 in each involucre ; ovary 3-lobed, soon pro- 

 truded on a long pedicel ; styles 3, each 2-oleft. Peduncles 

 terminal, often umbellate. 



* Leaves all similar and opposite, short-petioled, green or blotched with 



brown above, furnished with scale-like or fringed stipules. Stems 

 spreading or prostrate, much forked. Involucres in terminal or 

 lateral clusters, or one involucre in each fork, the involucre invari- 

 ably with 4 {mostly petal-like) glaTids in the sinuses. 



1. E. polygonifo'lia, L. Leaves entire, oblong-linear, 

 mucronate, very smooth. Stipules bristly-fringed. Ped- 

 uncles in the forks. Glands of the involucre very small, not 

 petal-like. Pods obtusely angled. — Shores of the Great 

 Lakes, in sandy or gravelly places. 



2. E. serpens, H. B. K. Leaves entire, round-ovate, very 

 small, smooth. Stipules membranaceous, triangular. Ped- 

 uncles longer than the petioles, in loose clusters. Glands 

 of the small involucre with minute orenulate appendages. 

 Stems thread-like, prostrate. Pods acutely angled. Seeds 

 smooth. — London and westward, not common. 



3. E. glyptosper'ma, Engel. Leaves serrulate towards 

 the apex, linear-oblong, very unequal at the base. Stipules 

 lanceolate, cut into bristles. Peduncles as long as the peti- 

 oles, in dense lateral clusters. Glands in the small invo- 

 lucre with crenulate appendages. Stems erect-spreading.. 

 Pods sharply angled. Seeds sharply 4-angled, with 5 or 6 

 transverse wrinkles. — Gravelly soil. 



* * Only the uppermost or floral leaves whorled or opposite. Stems 



erect. Stipules none. Involucres 5-lobed ; inflorescence umbelli- 

 form, in the forks of the branches, and terminal. 



4. E. maeula'ta, L. Leaves serrulate, oblong-linear. 

 somewhat putrescent, with a brownish blotch in the centre, very 



