Flower:

Flowers are tiny and indistinct, in a flattish cluster at the top of the stem and branch tips. A small cup called a cyathium holds a single female flower surrounded by 4 to 8 male flowers. The cyathium is ~1/8 inch (2 to 3 mm) long, green with white fringe-like lobes along the top and a single (rarely 2), oval-oblong, yellow-green gland with no visible petal appendages. Male flowers have a single stamen with a pair of round sacs at the tip, holding creamy yellow pollen. Female flowers are stalked, have a clump of styles at the tip of a 3-sided to nearly round, green ovary.

The 2 to 4 leaf-like bracts at the base of the cluster are typically whitish at the base, giving the cluster a soft glow.

Leaves and stems:

Leaves are mostly opposite, though may be alternate on the upper plant, narrowly to broadly lance-elliptic, up to 4 inches (1 to 10 cm) long, blunt to pointed at the tip, tapering at the base to a stalk up to 1 inch (2.5 cm) long. Edges are mostly coarsely, bluntly toothed. The upper surface is hairless to sparsely hairy, often purple-spotted; the lower surface sparsely covered in stiff, tapered hairs that are distinctly widest at the base.

Stems are erect to ascending, usually branched, green to reddish, covered in minute, stiff, downward-pointing hairs with scattered longer, spreading to ascending hairs. Leaves and stems exude milky sap when broken.

Fruit:

Fruit is a capsule with 3 round lobes, 4 to 5 mm diameter at maturity, the remains of the styles persisting at the tip.

Seed is 2.4 to 2.9 mm long, oval to egg-shaped, angled in cross-section, the surface light gray to brown-black and irregularly covered in bumps and ridges.

Notes:

David's spurge is said to be native to northern Mexico and the US from the southwest to the southern Great Plains, though USDA and some other references call it introduced to all of the US. In either case, it is considered not native to Minnesota. Populations here were long thought to be the related Euphorbia dentata (Toothed Spurge), but we're now realizing that is not the case and E. dentata is likely not here at all. When the existing herbarium records are finally reviewed that will probably hold true, but we're keeping an open mind.

While E. davidii and E. dentata are quite similar, the most obvious characteristic they share is the whitish base on floral bracts, there are a few distinctions that can quickly separate them. Fruit may be the most reliable, the capsules of E. davidii 4 to 5 mm diameter at maturity, the seeds irregularly bumpy/ridged and angled in cross-section, where E. dentata capsules are 3.5 to 4 mm diameter, seeds evenly covered in small bumps and rounded in cross-section. Also, the leaf hairs of E. davidii are stiff and tapered, noticeably broadest at the base, where E. dentata hairs are more thread-like, softer and not tapered, and E. davidii rarely has 2 glands on the cyathium where E. dentata usually does. As always, a hand lens is helpful.