Abstract
Results of recent molecular phylogenetic analyses have shown that the previous separation of Trillium into two subgenera based on pedicellate or sessile flowers is untenable. An updated infrageneric classification is presented recognising four subgenera in the genus, consistent with phylogenetic analyses. The three clades of pedicellate-flowered species are recognised here as subgenera: subgen. Trillium, Delostylis and newly named Callipetalon. The fourth, Trillium subgen. Sessilia, includes all sessile-flowered species. Orthographic considerations necessitate corrections to two previously published subgeneric names: Delostylium and Sessilium should be Delostylis and Sessilia.
References
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Millam, K.C. (2006) The Trillium erectum species-complex (Melanthiaceae): insights from molecular systematics and biogeography. Ph.D. dissertation, University of Wisconsin-Madison, 97 pp.
Miller, C.N., Pape?, M., Schilling, E.E. & Kwit, C. (2021) Reproductive traits explain occupancy of predicted distributions in a genus of eastern North American understory herbs. Diversity and Distributions 27: 1489–1506. https://doi.org/10.1111/ddi.13297
Miyabe, K. & Tatewaki, M. (1936) Contributions to the flora of northern Japan VII. Transactions of the Sapporo Natural History Society 14: 181–192.
Muhlenberg, G.H.E. (1813) Catalogus plantarum Americae septentrionalis. Hamilton, Lancaster, 112 pp.
Munz, P.A. & Thorne, R.F. (1973) A new northern California Trillium. Aliso 8: 15–17. https://doi.org/10.5642/aliso.19730801.13
Murray, A.E. (1983) Notae spermatophytae no. 2. Kalmia 13: 3–32.
Murray, A.E. (1984) Notae spermatophytae no. 4. Kalmia 14: 2–24.
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Nieuwland, J.A. (1913) Notes on our local plants.–IV. American Midland Naturalist 3: 98–125. https://doi.org/10.2307/2993085
Nuttall, T. (1818) The genera of North American plants and a catalogue of the species, to the year 1817, vol. 1. Heartt, Philadelphia, 312 pp. https://doi.org/10.5962/bhl.title.6134
O’Neill, D.M., Farmer, S.B., Floden, A., Lampley, J. & Schilling, E.E. (2020) Trillium hibbersonii (Melanthiaceae), a phylogenetically distinct species from western North America. Phytotaxa 436: 193–195. https://doi.org/10.11646/phytotaxa.436.2.9
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Piper, C.V. (1899) New and noteworthy northwestern plants.–I. Erythea 7: 104. https://doi.org/10.2307/2478251
Pursh, F.T. (1813) Flora Americae septentrionalis, vol. 1. White & Cochrane, London, 358 pp.
Rafinesque Schmaltz, C.G. (1808) Essential generic and specific characters of some new genusses and species of plants observed in the United States of America, in 1803 and 1804. Medical Repository 5: 356–363.
Rafinesque, C.S. (1819a) Prodrome: des nouveaux genres de plantes observés en 1817 et 1818 dans l’intérieur des États-Unis d’Amérique. Journal de Physique, de Chimie, d’Histoire Naturelle et des Arts 89: 96–107.
Rafinesque, C.S. (1819b) Art. 3. The genera of North-American plants and a catalogue of the species to the year 1817. By Thomas Nuttall, F.L.S. American Monthly Magazine & Critical Review 4: 184–196.
Rafinesque, C.S. (1820) D’un nouveau genre de plantes, Enemion, et remarques botaniques. Journal de Physique, de Chimie, d’Histoire Naturelle et des Arts 91: 70–72.
Rafinesque, C.S. (1830) Medical flora. Atkinson, Philadelphia, 276 pp.
Rafinesque, C.S. (1840) Autikon botanikon. By the author, Philadelphia, 200 pp.
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