ABSTRACT
Epilobium adenocaulon Hausskn. (Onagraceae) is a wild herbaceous species which was introduced from North America into Europe and southeast England from whence it has spread to most of the U.K., where it was first recorded in 1891. It is a many-branched perennial which, however, does not form stolons. It is described in the Flora of the British Isles 1 as being closely related to the North American E. glandulosum but less robust. It is a particularly useful plant for photoperiodic experimentation, forming compact rosettes in unfavorable daylengths and displaying a high degree of uniformity between plants when grown from seeds, which may possibly indicate a narrow genetic base. There are virtually no references to this species in the plant physiological literature.
