Ouachita Mountain Goldenrod

Historically Solidago ouachitensis has been included in S. caesia or S. curtisii; it is ecologically and morphologically distinct.

Solidago ouachitensis is known only from the mesic, north-facing slopes of the Ouachita Mountains along the border of Arkansas and Oklahoma. It is a very infrequent species deserving protection and is in the Center for Plant Conservation’s National Collection of Endangered Plants.

Plants 60–110 cm; caudices woody. Stems 1–3+ , erect, straight, glabrous proximally to sparsely hairy in arrays. Leaves: basal withering by flowering; proximal cauline sessile, blades elliptic, 100–130 × 35–45 mm, margins sharply serrate (with 20–31 teeth), abaxial faces glabrous, adaxial glabrous or sparsely hairy; distal cauline sessile, blades narrowly elliptic, 65–80 × 13–24 mm, bases cuneate, margins entire to slightly serrate, apices acuminate, faces glabrous. Heads 25–50, in non-secund, short, axillary and terminal racemiform/paniculiform arrays 13–25 cm. Peduncles 0.5–3 mm, sparsely hispido-strigose; bracteoles ovate, 1–3 near each head, grading into phyllaries. Involucres narrowly campanulate, (6.5–)7–8 mm. Phyllaries in ca. 3–4 series, unequal, 1-nerved, obtuse; outermost linear-oblong, 0.8–1.3 mm. Ray florets 1; laminae 2.4–4.7 × ca. 1 mm. Disc florets 4–5; corollas 1.8–2.8 mm, lobes 0.8–1.6 mm. Cypselae 1.5–2.7 mm, glabrous; pappi 3–3.5 mm. 2n = 18.

Solidago ouachitensis is a North American species of flowering plants in the family Asteraceae known by the common name Ouachita Mountain goldenrod. It has a very limited range, found only in the Ouachita Mountains along the border between Arkansas and Oklahoma in the United States.

Solidago ouachitensis is a perennial herb growing up to about 1.1 meters (44 inches) in height. It produces one or more erect stems from a woody caudex. The serrated (toothed) leaves are 10 to 13 centimeters (4.0-5.2 inches) long around the middle of the plant and smaller higher on the stem. One plant will produce 25-50 bell-shaped flower heads. Each flower head usually contains one yellow ray floret and 4-5 disc florets. Flowering occurs in September and October.

Solidago ouachitensis is likely a relict of times when conditions were colder and wetter. It only occurs in the cooler, moister sites in the Ouachita Mountains, usually in wet forest habitat on north-facing slopes. Associated species include Magnolia tripetala, Fagus grandifolia, Acer rubrum, Quercus rubra, Aesculus glabra, Asarum canadense, Campanula americana, Panax quinquefolium, Toxicodendron radicans, and Hybanthus concolor.