Plants with milky juice and monoecious flowers, represented in Canada chiefly by the two following genera:

1. Euphorbia

L. Spurge. Flowers monoecious, the sterile and fertile ones both destitute of calyx and corolla, but both contained in the same 4-5-lobed cup-shaped involucre which resembles a calyx, and therefore the whole will probably at first sight be taken for a single flower. Sterile flowers numerous, each of a single naked stamen from the axil of a minute bract. Fertile flower only 1 in each involucre; ovary 3-lobed, soon protruded on a long pedicel; styles 3, each 2-cleft. 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 invariably with 4 {mostly petal-like) glands in the sinuses.

1. E. polygonifo'lia, L. Leaves entire, oblong-linear, mucronate, very smooth. Stipules bristly-fringed. Peduncles 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. Peduncles longer than the petioles, in loose clusters. Glands of the small involucre with minute crenulate 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 petioles, in dense lateral clusters. Glands in the small involucre 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. maculata, L. Leaves serrulate, oblong-linear. somewhat pubescent, with a brownish blotch in the centre, very oblique at the base. Peduncles in dense lateral clusters. Glands of the involucre with reddish petal-like attachments. Pods sharply angled. - Roadsides.

5. E. hypericifo'lia, L. Stem ascending. Leaves serrate, often with a red spot or with red margins, oblique at the base, ovate-oblong or oblong-linear. Peduncles in cymes at the ends of the branches. Glands of the involucre with white or occasionally reddish petal-like attachments. Pod smooth, obtusely angled. - Cultivated soil.

6. E. Corollata, L. Conspicuous for the 5 bright-white false lobes of the involucre, resembling petals; the true lobes very small. - Gravelly or sandy soil.

* * * Involucres chiefly in terminal umbels, and their glands always without petal-like attachments. Leaves without stipules or blotches, those of the stem alternate or scattered, the floral ones usually of a different shape, and whorled or opposite.

7. E. platyphyl'la, L. Umbel 5-rayed. Stem erect, 8-18 inches high. Upper stem-leaves lance-oblong, acute, serrulate, the uppermost heart-shaped, the floral ones triangular-ovate and cordate. Pod warty. - Shores of the Great Lakes.

8. E. Heliosco'pia, L. Umbel first 5-rayed, then with 3, and finally merely forked. Stem ascending, 6-12 inches high. Leaves all obovate, rounded or notched at the apex, serrate. Pods smooth. - Along the Great Lakes.

9. E. Cyparis'sias, L., with densely clustered stems, and crowded linear stem-leaves (the floral ones round heart-shaped), and a many-rayed umbel, has escaped from gardens in some localities.

10. E. PepluS, L., has the umbel 3-rayed, then forking.

Glands long-horned. Seeds ash-coloured, 2-grooved on the inner face, and pitted on the back. - Rather rare, waste places.

2. Acaly'pha. L. Three-seeded Mercury

A. Virgin'ica, L. Flowers monoecious, both kinds having a calyx, the staminate 4-parted, the pistillate 3-5-parted; no involucre. Staminate flowers very small, in spikes, with 1-3 pistillate flowers at the base, in the axil of a large leaf-like 5-9-lobed bract. Stamens 8-16, monadel-phous at the base, the anther-cells hanging from the apex of the filament. Styles 3, the stigmas cut-fringed, usually-red. Pod separating into 3 globular carpels. A nettle-like weed, with ovate, sparsely serrate, alternate, long-petioled leaves. - Fields and open places.