Distribution

c, e North America, Asia (Himalayas to e China, Japan, Russian Far East, Taiwan).

Discussion

Varieties 2 (1 in the flora).

Phryma leptostachya is a classic example of the eastern Asian/eastern North American disjunction pattern, which has long fascinated botanists. Two varieties are traditionally recognized: var. leptostachya in North America and var. asiatica H. Hara in eastern Asia. They are distinguished on minor differences in leaf size, shape of adaxial lip of the corolla, and length of the adaxial, spinulose calyx lobes (Nie Z. L. et al. 2006). Despite the morphological similarities, recent analyses demonstrate significant molecular divergence between the two varieties (N. S. Lee et al. 1996; Xiang Q. Y. et al. 2000; Nie et al. 2006, 2009b) and a North American origin of the genus with subsequent dispersal to eastern Asia approximately three to six mya has been hypothesized (Xiang et al.; Nie et al. 2006).

Ground roots of Phryma leptostachya and extracts of the entire plant have been used as insecticides in Asia (G. M. Hocking 1997), where it has been used also to treat fevers, ulcers, ringworms, scabies, boils, carbuncles, and cancers (D. F. Austin 2004). In the New World, the Ojibwa reportedly used it in the treatment of sore throat and rheumatism (Austin), as did the Chippewa (F. Densmore 1928).

Selected References

None.

Lower Taxa

Phryma leptostachya var. leptostachya