Euphorbia hirsuta.=

7b. Seeds red --8.

8a. Leaves oblong =Spurge, Euphorbia maculata.=

8b. Leaves elliptical to obovate; involucre split down one side
=Spurge, Euphorbia humistrata.=

9a. Flowers subtended by conspicuous petal-like white appendages (part
of the involucre) (4-10 dm. tall; summer)
=Spurge, Euphorbia corollata.=

9b. Flowers not subtended by petal-like appendages --10.

10a. Stem-leaves below the inflorescence serrulate (2-5 dm. high;
summer) --11.

10b. Stem-leaves below the inflorescence entire --13.

11a. Upper leaves acute =Spurge, Euphorbia platyphylla.=

11b. Upper leaves obtuse, rounded, or notched at the apex --12.

12a. Leaves of the involucre broadly triangular-ovate, widest near
the base =Spurge, Euphorbia obtusata.=

12b. Leaves of the involucre broadly obovate to nearly circular,
widest near or above the middle
=Spurge, Euphorbia helioscopia.=

13a. Stem-leaves narrowly linear, less than 3 mm. wide (2-4 dm. high;
late spring and summer) =Cypress Spurge, Euphorbia cyparissias.=

13b. Stem-leaves narrowly oblong-spatulate, more than 5 mm. wide, and
more than 3 times as long as wide (2-6 dm. high; summer) --14.

13c. Stem-leaves obovate to nearly circular, not more than twice as long
as wide (1-4 dm. high) --15.

14a. Leaves at base of umbel narrow, resembling those on the stem
=Spurge, Euphorbia esula.=

14b. Leaves at base of umbel broad, resembling those of the
inflorescence =Spurge, Euphorbia lucida.=

15a. Upper stem-leaves distinctly narrowed at the base; introduced
species of waste places (summer) =Spurge, Euphorbia peplus.=

15b. Upper stem-leaves rounded at the sessile base; native species of
woodlands (spring and early summer) =Spurge, Euphorbia commutata.=

CALLITRICHACEAE, the Water Starwort Family

Small herbs growing in water or in mud, with opposite entire leaves and
small inconspicuous axillary flowers, with neither calyx nor corolla.
(Flowers in summer).

1a. Completely submerged; leaves all linear
=Water Starwort, Callitriche autumnalis.=

1b. Submer