Description from Flora of China
Herbs, annual or perennial [or subshrubs to shrubs], erect, prostrate, creeping to ascending. Stems 4-angular or winged or terete, occasionally highly reduced. Stipules absent. Leaves simple, opposite; leaf blade margin serrate or entire or variously toothed. Inflorescences a terminal [or axillary] spike [or a terminal raceme or a cyme] or flowers solitary and axillary. Flowers perfect, with [or without] a bract and a bracteole. Calyx connate, 5-lobed or dentate; lobes usually less than 1/3 of calyx length. Corolla connate, tubular or cylindric, 2-lipped; lower lip with 3 imbricate lobes; upper lip 2-lobed. Stamens [2 or]4, inserted in corolla tube or exserted, anterior 2 longer; anthers longitudinally dehiscent. Gynoecium of 2 connate carpels; ovary superior, 1- or 2-locular; stigma broadly 2-lobed to 2-lipped, receptive only on inner surface and close together upon contact. Fruit an achene (in Phryma), loculicidal capsule (e.g., in Mimulus Linnaeus) [or occasionally berrylike (in Leucocarpus D. Don)]. Seeds numerous, rarely to 1, with an oblong embryo; endosperm scanty.
Z. Yu Li (in FRPS 70: 314-317. 2002) treated Phrymaceae to include only the genus Phryma, but recent studies have shown that the family should include a number of genera previously considered to be part of Scrophulariaceae. For China Phrymaceae now includes Mimulus with five species (four endemic), which has already been treated for the Flora of China in Scrophulariaceae (D. Y. Hong & N. H. Holmgren, Fl. China 18: 40-41. 1998), and Phryma with a single species. Two additional genera from Scrophulariaceae in China, Mazus Loureiro and Lancea J. D. Hooker & Thomson, were included in Phrymaceae by P. R. Beardsley and R. G. Olmstead (Amer. J. Bot. 89: 1093-1102. 2002), but we have excluded these two genera from Phrymaceae (see B. Oxelman et al., Taxon 54: 411-425. 2005; Z. Xia et al., Amer. J. Bot. 96: 519-530. 2009).
Yang Han-pi. 1979. Mimulus. In: Tsoong Pu-chiu & Yang Han-pi, eds., Fl. Reipubl. Popularis Sin. 67(2): 164-172; Li Zhenyu. 2002. Phrymaceae. In: Hu Chiachi, ed., Fl. Reipubl. Popularis Sin. 70: 314-317.
About 14 genera and 150 species: worldwide, especially well developed in W North America and Australia; two genera and six species (four endemic) in China; one species treated here, one genus and five species previously treated in Fl. China 18 (see comment below).
(Authors: Hong Deyuan (洪德元); Jun Wen (文军))