Tall Rattlesnakeroot (Nabalus altissimus) vs Three-leaved Rattlesnake Root (Nabalus trifoliolatus)
This guide is under construction and has not been published yet. It may have errors. When in doubt, double-check other sources for definitive ID.These two species are visually similar and frequently confused. N. altissimus ranges much farther west, farther north, and slightly farther south, and prefers drier, slightly shadier habitats. N. trifoliatus extends farther east (closer to the coast) in the central portions of its range, prefers moister and slightly sunnier habitats, and is tolerant of some soil salinity.
Tall Rattlesnakeroot (Nabalus altissimus) | Three-leaved Rattlesnake Root (Nabalus trifoliolatus) |
Thought to be a monocarpic perennial, native to forests in eastern North America, often on somewhat acidic soils. | |
 Flowerheads usually have 4-6 florets. Photo © Chris Angell, CC BY 4.0. |  Flowerheads usually have 8-15 florets. Photo © Ingolf Askevold, Public Domain. |
 Flowerheads usually have 4-6 phyllaries (bracts or leaf-like structures enclosing each flowerhead.) Phyllaries may have small blackish areas at both base and tip, but are more consistently pale green, with less color variation from base to tip. Involucre (cluster of all bracts) is narrower and often as few as 2 bracts are visible from the side. Photo © John Brown, Public Domain. |  Flowerheads usually have 7–10 phyllaries. Phyllaries are often darker green to blackish at the base, and fade to paler at their tips. Involucre is wider and often as many as 4 or more bracts are visible from the side. Photo © agbelliveau, Public Domain. |
References & External Resources
These short lists show only links helpful for ID. For a complete list of references and resources also covering other aspects of ecology, visit the links section of the full article on each plant, which is the first entry here.
