The North American species of Placynthium
Canadian Journal of Botany
A general survey is given of the morphology and anatomy of the genus Placynthium.
The species: aspratile, flabellosum, nigrum incl. v. tantaleum, petersii,
subradiatum, and stenophyllum are described in detail. The following new combinations
are made: Placynthium filiforme, Placynthium aspratile, Placynthium
subradiatum f. coerulescens, and Synalissa subnigra. The new variety Placynthium
stenophyllum v. isidiatum is established.