Euphorbia maculata L., spotted spurge. Annual, taprooted, several—many–stemmed at base, mat–forming, branches diverging at 20—30°, prostrate, spreading to 40 cm, not rooting at nodes, typically < 2 cm tall; monoecious; shoots strongly 2–dimensional (plagiotropic) with zigzagged axes, pilose; latex white, copious.
Stems cylindric, typically ± 1 mm diameter, flexible, green soon turning pinkish brown except on unexposed surfaces, nodes swollen, internodes 3—35 mm long.
Leaves opposite decussate, simple, short–petiolate, with stipules; stipules 2 (4 per node), free, attached to node, narrowly acuminate, to 2 mm long, upper < lower, white to pink, fringed–lobed and sometimes divided to base, ciliate on margins; petiole 0.5—2 mm long, curved to orient leaves horizontally; blade ovate to oblong, 3—13 × 1—7.5 mm, oblique to 1–lobed (semicordate) at base, minutely serrate and sometimes reddish on margins, obtuse or rounded (acute) at tip, pinnately veined with very fine network of minor veins, pilose or glabrous, the hairs when present sparser on upper surface, upper surface gray–green to dark green and often with a dark reddish central area, lower surface lighter in color and glaucous.
Inflorescence cyathium (= involucre with staminate flowers and 1 pistillate flower), axillary, in leafy, cymelike arrays; peduncle ≈ length of cyathium; cyathium to 0.8 mm wide (including spreading glands and appendages); involucre funnel–shaped to urn–shaped, ± 1 × 0.6 mm, green, pubescent, with 5 bracts and 4 glands, the bracts of involucre fused most of length, acute to acuminate free tips, the tips ± 0.25 mm long, whitish, ciliately fringed, the glands alternate with bracts (1 absent), nectar–producing, raised, transversely elliptic, 0.15 × ± 0.3 mm, fleshy, yellowish green to yellowish orange or reddish pink to light pinkish yellow, depressed in center, appendaged from just below gland, the appendage petal–like, < or > gland, whitish to pale pinkish, entire or weakly scalloped on outer margin; staminate flowers 4—5, never in clusters, each with pedicel–like stalk, each flower associated with a bractlet; bractlet linear, ± 0.5 mm long, white, fringed, the pedicel short; pistillate flower on a pedicel–like stalk (gynophore), at anthesis gynophore short and erect, with only styles exposed, soon after gynophore elongating and becoming recurved with maturing ovary exserted.
Staminate flower reduced to 1 stamen; filaments < 0.2 mm long; anthers conspicuously dithecal, each sac broadly ellipsoid, ± 0.2 mm long, yellowish green becoming reddish, longitudinally dehiscent; pollen yellow.
Pistillate flower reduced to 1 pistil; ovary superior, 3–lobed broadly ovoid, ± 0.5 mm, light green with or without pink to reddish edges, ± uniformly strigose, 3–chambered, each chamber with 1 ovule; styles 3, 0.3—0.4 mm long, 2–branched at midpoint, the branches club–shaped, fleshy, light green to pinkish below and ± colorless to transparent pink at tip; stigmas minute.
Fruit capsule, 3–seeded, 3–lobed and broadly triangular–ovoid, 1.3—1.5 mm long, strigose, elastically dehiscing along septa and chambers into 6 dry valves (some valve–pairs remaining attached at base) and expelling seeds.
Seed quadrangular–ovoid, 0.8—1.2 × 0.5—0.7 mm, orangey brown beneath frosty–white epidermis, transversely wrinkled, grooved on obtuse, lower ridge, ± acute on other ridges.
A. C. Gibson & B. A. Prigge