63. Rumex bucephalophorus Linnaeus, Sp. Pl. 1: 336. 1753.
Horned, red, or ruby dock
Bucephalophora aculeata Pau; Lapathum bucephalophorum (Linnaeus) Lamarck
Plants annual, rarely biennial [perennial], glabrous or nearly so, with fusiform vertical root. Stems branched from base or near base, occasionally simple, slender, 5-50 cm. Leaves: ocrea deciduous or partially persistent; blade spatulate, lanceolate, or ovate-lanceolate, 1-5(-8) × (0.5-)1-2.5 cm, base cuneate, rarely rounded, margins normally entire, flat, apex obtuse. Inflorescences terminal, simple, racemose, occupying most of stem, interrupted, linear. Pedicels usually distinctly heteromorphic (much thickened distally), 4-7(-10) mm; others less than 4 mm. Flowers 2-3(-4) in lax clusters (reduced whorls); inner tepals variable, often heteromorphic, triangular, narrowly triangular, ligulate, or ovate-oblong, (1.5-)2-4(-5) × (0.5-)1-3 mm (excluding teeth), base truncate, margins usually dentate, sometimes entire, apex obtuse or acute, usually not hooked, teeth 2-4(-8), at each side of margins, slender, straight or hooked, 0.3-1 mm; tubercles absent, or 3, usually represented by minute swellings barely recognizable as tubercles. Achenes brown to dark brown, 1.3-2.3 × 0.7-1.4 mm. 2n = 16.
Flowering summer. Ruderal habitats, ballast grounds; 0 m; introduced; La.; s Europe; w Asia; n Africa; occasionally introduced in other regions.
Rumex bucephalophorus is a polymorphic species, especially within its native range. K. H. Rechinger (1939, 1964) and J. R. Press (1988) recognized several subspecies, but no attempt has been made to distinguish infraspecific taxa among the limited North American materials. This species occurs in the flora area as an uncommon, casual alien. It has the potential to naturalize in the southern United States, especially in coastal regions from the Carolinas to Texas, and in California.