3. Galium arkansanum A. Gray (Arkansas bedstraw)

Pl. 546 a, b; Map 2537

Plants perennial. Stems 15–35(–50) cm long, erect or ascending, sometimes from a spreading base, unbranched or few-branched from the base, glabrous or sparsely to moderately pubescent with short, straight, soft, spreading to loosely upward-angled hairs, especially at the nodes. Leaves 4 per node, spreading in orientation or very slightly arched downward. Leaf blades 7–45 mm long, 2–9 mm wide, lanceolate to narrowly lanceolate, angled to a bluntly or more commonly sharply pointed tip, angled or slightly tapered at the base, the undersurface with impressed, linear glands (appearing as small streaks or lines), otherwise glabrous or roughened with short, stiff hairs along the midvein, the venation palmate with 3 veins (the midvein and 2 finer lateral veins) visible, but the lateral veins often weak, the margins with short, stiff, prickly hairs and flat or only slightly curved under. Inflorescences terminal and axillary from the upper leaves, not pendant, positioned over the leaves, consisting of small panicles (occasionally some of these reduced to simple clusters) with mostly 1–3 branch points and relatively long, ascending branches. Flowers relatively few to more numerous, the stalks 10–20(–28) long. Corollas 1.5–2.0 mm long, 4-lobed, dark red, purple, or maroon. Fruits 2–4 mm long, 3.5–5.0 mm wide, the surface minutely roughened (the tubercles less than 0.1 mm long), otherwise glabrous. May–June.

Scattered in the Ozark Division and also in Scott County (Arkansas, Missouri, and Oklahoma). Mesic to dry upland forests, edges of glades, and ledges of bluffs; also roadsides.

The corolla lobes often terminate in rather long filaments that are sometimes paler in color. Two varieties of Galium arkansanum have been recognized by some botanists: var. arkansanum and var. pubiflorum E.B. Sm. E. B. Smith (1979) separated var. pubiflorum based on its corollas that are densely pubescent on the exterior with long silky hairs (vs. glabrous in var. arkansanum) and its leaves 2.5–3.5 mm wide with generally only the midvein visible (vs. 5–8 mm wide and 1- or 3-veined in var. arkansanum). He noted that pure var. pubiflorum is known only from one county in southwestern Arkansas, and that continuous variation from fully glabrous to fully pubescent flowers is found among the rest of the populations in southern Arkansas, which frequently also contain plants spanning the full range of leaf widths for the species. In his discussion, E. B. Smith referred to his these varieties as phases, and documented the many intermediate forms. Thus, no infraspecific taxa are recognized in the present treatment.

Galium latifolium Michx. of the Appalachian Mountains is similar to G. arkansanum. It differs in its broader leaves (9–20 mm), its generally well-developed lateral leaf veins, and its shorter flower stalks (4–8 mm).