形态特征：Perennial herbs. Rhizomes fleshy, white, horizontal. Root thin, fibrous. Stems erect, unbranched, glabrous, up to 30 cm tall, old stems quadrangular, glabrous, young stems inconspicuously quadrangular to obtusely ribbed, minutely puberulent. Leaves opposite, petiole inconspicuous to nearly absent; leaf blade narrowly lanceolate, 5.5–8.5 × 0.8–1.1 cm, submembranaceous to papery, adaxially green, pubescent, abaxially pale green, (sub)glabrous, base cuneate, margin basally entire and apically sparsely serrate, apex acute to long acuminate; lateral veins 3–5 pairs, abaxially raised and adaxially slightly depressed. Racemes terminal, 3–6 cm, flowers remarkably sparse, less than 6; pedicels 4–7 mm, sparsely puberulent; bracts tiny, narrowly lanceolate to linear. Calyx funnelform, 4–6 mm, sparsely pubescent outside, subglabrous inside, 5-lobed; lobes narrowly triangular to lanceolate, as long as tube in length, midrib conspicuous, apex acute. Corolla creamy yellow, 1.8–2.2 cm long, densely puberulent outside; tube straight, cylindric, long exserted from calyx, gradually dilated; limb 2-lipped, reddish in throat, posterior lip bilobed, lobes orbicular, anterior lip trilobed, lobes subequal, rounded. Stamens 4, didynamous, inserted on corolla tube, included, anterior pair longer; anthers bithecal, locules divergent, apically connivent; filaments filiform, glabrous. Styles included, glabrous, persistent; stigma 2-lamellate. Capsule ovoid, ca. 2 × 3 mm, glabrous.
生活型：多年生草本；
株：高20-30厘米，干时变黑色，全体无毛或很快变为无毛；
茎：茎多枝，直立，四方形，纤细；
叶：叶以茎生叶为主，全部对生，近于无柄，近基部的叶很小，鳞片状，倒卵状矩圆形，顶端圆钝，其余的叶披针形或狭披针形，近膜质，长6-9厘米，顶端急尖至长渐尖，基部楔形，边缘具稀疏或不明显的细锯齿，下面灰白色稍带粉绿，侧脉少而稀疏；
花：花小而少，约6朵排成纤细，蝎尾状顶生的总状花序；花梗较花短，纤细，苞片小，狭披针形，花萼漏斗状，长6-9毫米，萼齿5，与萼筒等长，披针形，顶端急尖，主脉明显，侧脉不明显；花冠（完全发育的未见）几不超过花萼；
果：蒴果卵圆形，端渐尖；
