A box or herbarium cabinet containing any specimens of valerian will emit, when opened, a strong, long-persistent “valerianic odor” so characteristic of these plants, an odor also evident when one digs up the underground parts. Yet these pungent parts have been used as food when properly prepared, and they have a long reputation for medicinal value.
The incurved calyx unfurls and elongates on the mature fruit, where it resembles a pappus of plumose bristles, as in some Asteraceae. The flowers in Valeriana are bisexual or unisexual, usually mixed on an individual and with corollas of differing lengths. Corolla measurements in the key below are based on mature corollas of the larger flowers (i.e., staminate or bisexual, not pistillate ones, which run smaller).
1. Rachis of cauline leaves broader than the lateral lobes; leaf margins very densely ciliate; plant with a large (sometimes branched) taproot; inflorescence becoming longer than broad; corollas ca. 2.7–4 mm long.
1. Rachis of cauline leaves narrower than the lateral lobes; leaf margins moderately to sparsely ciliate; plant rhizomatous; inflorescence often as broad as long or broader; corollas various.
2. Basal leaves all deeply divided (similar to cauline leaves); cauline leaves with (6–) 7–9 pairs of lateral lobes (or leaflets), these with short, mostly antrorse marginal cilia; longer corolla tubes ca. 2.5–4 mm long; escaped from cultivation to roadsides, ditches, and fields.
2. Basal leaves all or mostly simple, at most with one pair of small lobes; cauline leaves with 2–5 (–7) pairs of lateral lobes (or leaflets), these with marginal cilia (if any) mostly spreading and often ± contorted; longer corolla tubes ca. (3.5–) 4–6 mm long; native in fens and conifer swamps.
All species found in Valeriana
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. January 18, 2018. http://michiganflora.net/genus.aspx?id=Valeriana.