Herbs perennial, herbaceous or suffrutescent, with shoots from caudex. Stems ± woody at base, epidermis not peeling proximally. Leaves opposite proximal to inflorescence or throughout, alternate and/or fasciculate distally. Flowers slightly zygomorphic (upper petals ± flared at right angle to calyx tube, lower ones parallel with it), spread laterally to suberect; floral tube elongate, bulbous near base, with irregular scales inside at base of staminal filaments; floral tube, sepals, and petals usually orange-red, very rarely white; pollen in tetrads; stigma deeply 4-lobed. Capsules subclavate to fusiform, splitting to base, central column persistent, subsessile to short-pedicellate. Seeds numerous, in 1 row per locule, ± broadly obovoid, prominently constricted near micropylar end; coma present.

Distribution

w North America, n Mexico.

Discussion

Species 2 (2 in the flora).

Section Zauschneria, with its relatively large, tubular, red-orange flowers commonly polli­nated by hummingbirds, differs sharply in aspect from the rest of Epilobium, and until recently (P. H. Raven 1976) was treated as a separate but related genus (for example, P. A. Munz 1965). The section consists of two species (four taxa) endemic to western North America, one of which is diploid (E. septentrionale, n = 15) and the other polyploid (E. canum, n = 15, 30). The latter is the only species in Epilobium, other than the allopolyploid E. subdentatum (sect. Pachydium), with polyploidy above the paleotetraploid level of x = 18. Despite their distinctive flowers, these taxa fit well within Epilobium, possessing seed comas and numerous similarities in pollen and seed morphology, especially to taxa in sections Cordylophorum and Xerolobium (Raven). Molecular analyses (D. A. Baum et al. 1994; R. A. Levin et al. 2004) placed sect. Zauschneria (x = 15) in a well-supported clade with sects. Epilobiopsis (n = 15) and Pachydium (n = 9, 10, 19), which together were previously segregated as Boisduvalia. Within this clade, Levin et al. found strong support for sect. Zauschneria as sister to sect. Pachydium, a surprising relation­ship based on morphology and cytology.

Section Zauschneria occurs primarily in the California Floristic Province (P. H. Raven and D. I. Axelrod 1978), except for Epilobium canum subsp. garrettii, which is confined primarilyto the Great Basin Province (R. F. Thorne 1993d). In addition, E. canum subsp. latifolium extends into the desert ranges of the Sonoran Province (Thorne).

Section Zauschneria is sufficiently variable especially in vestiture and leaf size and shape that it was once considered to include 20 species (G. L. Moxley 1920). J. D. Clausen et al. (1940) treated the group as three diploid species and one tetraploid species with three subspecies; P. A. Munz (1965) recognized the same six taxa. P. H. Raven (1976) further reduced these to six subspecies of one variable species, one of which (the diploid Epilobium septentrionale) subsequently reinstated at the species level (R. N. Bowman and Hoch 1979).

Selected References

None.

Lower Taxa

Epilobium canum, Epilobium septentrionale