Nabalus is a genus of about 20 species of flowering plants in the tribe Cichorieae, within the daisy family Asteraceae (order Asterales). The genus has a disjunct distribution, with species native to eastern Asia — including Japan, Korea, China, and the Russian Far East — and to North America, where species range from the Pacific Northwest and Great Plains east through the Great Lakes region, the Appalachians, and into the southeastern United States.
The genus was long treated as part of the related genus Prenanthes, and in the Flora of North America treatment the North American species were included in that genus. Subsequent taxonomic work established that Nabalus is the correct name for this group, and it is now recognised as a distinct genus. Common names such as "rattlesnake root" and "white lettuce" are widely applied across North American species; the name "white lettuce" reflects the genus's close relationship to cultivated lettuce (Lactuca sativa), and the flower heads in many species are pale whitish or purplish-white.
A distinctive biological feature of many — and perhaps all — Nabalus species is that they are monocarpic perennials. Unlike most herbaceous perennials, a monocarpic plant may persist in a vegetative state for several years before flowering, then dies after setting seed. The flower heads are small and nodding, arranged in racemes or panicles, and are characteristic of the chicory tribe in lacking ray florets differentiated from disc florets in the typical sense.
Distribution
The genus spans eastern Asia (Japan, Korea, China, and Primorye in the Russian Far East) and North America. North American species occur broadly from western Canada (British Columbia, Alberta) and the Pacific Northwest south and east through the Great Plains, Great Lakes, Northeast, Appalachians, and into the southeastern United States. Some species are restricted to narrow ranges such as the southern Appalachians.
Taxonomy Notes
Nabalus was formerly subsumed within Prenanthes, and the North American species were treated under that name in the Flora of North America. Subsequent revision recognised Nabalus as the correct and accepted name for the group. GBIF currently accepts the genus within Asteraceae (tribe Cichorieae) with approximately 20 species.
