Galium arkansanum A. Gray
CC = 6
CW = 5
MOC = 27
Family - Rubiaceae
Habit - Perennial forb.
Stems - Ascending to erect, to 35 cm, 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 upwardangled hairs, especially at the nodes.
Leaves - In whorls of 4, spreading in orientation. 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 lateral veins visible but usually faint, the margins with short, stiff, prickly hairs and flat or only slightly curved under.
Inflorescence - Terminal and axillary small panicles from the upper leaves, not pendent, positioned over the leaves, with mostly 1-3 branch points and relatively long, ascending branches. Flowers relatively few to more numerous, the stalks 10-20 long.
Flowers - Corollas 1.5-2.0 mm long, 4-lobed, purplish-red, glabrous. Lobes acute to apiculate, spreading, the apices often whitened. Stamens 4, spreading. Filaments purple, 0.6 mm long. Anthers purple, 0.2 mm long. Style purple, glabrous, 0.5 mm long. Stigma 2-lobed. Ovary inferior, 2-carpellate, green, glabrous, 1.2 mm long, with one ovule per carpel.
Fruits - Dry schizocarps 2-4 mm long, 3.5-5.0 mm wide, the surface minutely roughened (the tubercles less than 0.1 mm long), otherwise glabrous.
Flowering - May - June.
Habitat - Upland forests, glade margins, ledges of bluffs, roadsides.
Origin - Native to the U.S.
Lookalikes - Broadly, other species of Galium, including G. pilosum, G. circaezans, and others.
Other info. - This little plant is found in the Ozark region of Missouri, mostly within the southern quarter of the state. This is the top edge of its global range, which extends to only two other states (Arkansas and Oklahoma). The plant is easy to ID in the field from its four lanceolate leaves and its purple-red flowers. G. pilosum has similar flowers, but the ovaries and fruits of that species bear hooked bristles. The leaf shape of G. arkansanum is quite distinctive and easily recognized with a little practice.
Photographs taken off Hwy 106, Shannon County, MO., 6-6-03 (DETenaglia); also at Noblett Lake, Howell County, MO, 6-2-2017, and Taum Sauk State Park, Iron County, MO, 8-4-2020 (SRTurner).