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).