Perennial herbs with quadrangular stem. Leaves simple, opposite, petiolate, exstipulate. Inflorescence spicate and flowers becoming strongly reflexed after fruiting. Bracts and bracteoles linear and small. Flowers herma¬phrodite, zygomorphic, pink or pale purple. Calyx bilabiate, tubular, persistent, lobes 5, unequal. Corolla tubular, 5 lobed, bilabiate, lower lip larger than the upper. Stamens 4, didynamous, included or slightly exserted, anthers bithecous, subreni¬form, dehiscing longitudinally, pollen grains tricolpate, subprolate. Carpels 2, syncarpous; ovary superior, oblong, unilocular, ovule solitary, nearly erect from the base, orthotropous; style terminal; stigma simple, very shortly bifid. Fruit caryopsis with membranous pericarp, enclosed by the persistent, ribbed, reflexed, 3 hooked calyx. Seeds exalbuminous; embryo oblong, cotyledons oval and folded.
A family of a single monotypic genus (Phryma leptostachya) with discontinuous distribution in eastern-north America and north-eastern Asia (Canada in the Atlantic States southwards to Florida and also Himalayas and in Japan).
The family was first recognized by Schauer (in DC. Prodr. 11:520.1847), but later on most of the taxonomists such as Bentham & Hooker (1876) and more recently Whipple (Journ. Elis. Mitch. Sci. Soc. 88 (1): 1-17-1972) treated it as a tribe of Verbenaceae. Schauer beautifully described the structure of the fruit (Caryo¬psideus monospermus) and of the seed (exalbuminosum, embryon rectum, radicula superacet.) beside its peculiar calyx (superiore (Labio) tripartite laciniis subulatis apice reduncis inferiore (Labio) brevissimo bifido). These characters are so dis¬tinct that Phryma can not be included under Verbenaceae even as an anomalous genus. Family Phrymaceae was ignored for many years until it was re-established by Briquet (Mem. Soc. Phys. Hist. Nat. Geneve 32:97.1894) in a paper dealing with the anatomy of Phrymaceae and later on in the treatment by the same author in Engler & Prantl, Nat. Pflanzenfam. Engler, Bessey and Wettstein and most American botanists, have accepted it as a separate family. Hutchinson (Families Fl. Pl. 1:398.1959) has treated as a separate family under the order Verbenales.
Acknowledgements: We are grateful to the United States Department of Agriculture for financing this research under P.L. 480. Thanks are also due to Mr. B.L. Burtt, Mr. Ian Hedge of the Royal Botanic Garden, Edinburgh for their helpful suggestions.