Description from Flora of China
Herbs, perennial. Stems short. Leaves opposite, rosulate, petiolate; leaf blade margin undulate, crenulate, or rarely subentire. Inflorescences terminal, spikes or thyrses; bracts usually subleaflike; bracteoles present. Flowers sessile. Calyx subequally to equally 5-lobed. Corolla white, bluish, or pink; tube basally cylindric and slender, apically expanded into a throat; limb 5-lobed; lobes subequal, contorted in bud, apex rounded or obtuse. Stamens 4, didynamous, inserted at base of throat; filaments glabrous; anthers 2-thecous; thecae usually widely separated by a broad connective, ± parallel; staminodes absent. Ovary glabrous, with 4-8 ovules per locule; style pubescent; stigma pubescent, 2-cleft, upper lobe very short or reduced. Capsule cylindric, not stipitate, 8-16-seeded; retinacula present. Seeds lenticular, pubescent with hygroscopic hairs.
Pararuellia is purported to differ from Ruellia by its pollen, which has "minute prickles, papillae or granules (not a honey-combed pattern)" (C. B. Clarke, J. Asiat. Soc. Bengal, Pt. 2, Nat. Hist. 74: 649. 1908) or at least papillae on the muri of reticulations (C. C. Hu et al., Acta Phytotax. Sin. 43: 123-150. 2005). Because such structures are also known from some species of Ruellia (C. A. Furness & M. C. Grant, Grana 35: 231-239. 1996), the generic status of Pararuellia is questionable and deserves additional study.
About ten species: SE Asia, China; five species (all endemic) in China.
(Authors: Hu Jiaqi (胡嘉琪 Hu Chia-chi), Deng Yunfei (邓云飞); Thomas F. Daniel)