Euphorbia celastroides var. celastroides is a shrub or small tree that can grow between 0.4 to 9 meters tall. The stems, which range from prostrate to erect, are glabrous and have flowering branches that are often nodose and measure 1 to 6 mm in diameter. The leaves are simple and opposite, arranged distichously, with narrowly obovate blades measuring 4 to 70 millimeters long and 3 to 30 mm wide, occasionally reaching up to 80 by 40 mm. The apex of the leaves can be acute to obtuse, retuse, or mucronulate, and the base ranges from cuneate to obtuse and oblique. Leaf surfaces are glabrous and sometimes glaucous, with entire margins. Petioles are 0.5 to 5 millimeters long, potentially up to 6 millimeters, and vary from glabrous to villous. Stipules are acute to rounded-triangular, 1 to 4 millimeters long, sometimes up to 6 mm, and can be glabrous to villous, erose, and ciliate. The flowers are in a cyathia in short or open-branched cymes or solitarily in leaf axils. Peduncles range from 0.5 to 10 mm long, up to 19 mm, and are glabrous to villous. The involucre is campanulate, 1 to 3 millimeters high, and 2 to 4 mm wide, with a glabrous surface to villous. The plant features 4 to 5 green or red glands that vary from glabrous to pilose. The flowers are unisexual and highly reduced, with solitary pistillate flowers on a gynophore and staminate flowers grouped in 5 cymules, each with one to several flowers. It lacks sepals and petals, with male flowers reduced to a single stamen articulated at the junction of the pedicel and filament and subtended by slender bracteoles. The ovary is superior, with styles that are yellow, green, or red, bifid less than or more than half their length, measuring 0.5 to 1 mm long, and ranging from glabrous to pubescent with a thickened stigma. The fruit is a capsule, green to brown, ovoid to rounded-triangular, measuring 0.5 to 4 millimeters long, and can be glabrous to pubescent. Gynophores are erect and exserted 0.5 to 1 millimeter from the involucre, ranging from glabrous to pubescent. The seeds are brown to gray, measuring approximately 1.5 to 2 millimeters long, and are tetragonal to obcompressed with a surface that is smooth to rugose. It occurs in coastal vegetation and mesic forests, with elevations ranging from 0-365 meters.