Two New Orders for Monocotyledonous Plants

Abstract

Two new orders, Tofieldiales and Nartheciales, are proposed for two phylogenetically isolated groups of monocotyledonous families, Tofieldiaceae and Nartheciaceae, long associated with a polyphyletic Melanthiales. Tofieldiales is better considered a member of the Alismatidae, being tentatively considered a member of the Alismatanae and the sister group of Alismatales (s.1.). Nartheciales remains a member of the Liliidae, forming a basal group within Lilianae. Recent work on the genera of monocotyledonous plants for the Generic Flora of the Southeastern United States by Zomlefer (1996, 1997a, b, c) has demonstrated the need for a series of nomenclatural modifications that more accurately reflect the results of ongoing phylogenetic studies. With Melanthiaceae being shown to be polyphyletic (e.g., Chase et al., 1993, 1995a, b), adoption of Tofieldiaceae Takhtajan and Narthecaceae Fries ex Bjurzon is a logical conclusion. Their placement within the monocots is still somewhat problematic, with the molecular and morphological evidence presented by the above cited authors suggesting that Tofieldiaceae should be considered the sister group of a broadly defined Alismatales (in the Alismatanae, Alismatidae). Nartheciaceae, however, should remain associated with the Lilianae (in Liliidae) as a basal member of that superorder. What is not problematic is that both families belong to their own order, neither of which is currently published. Accordingly, the following two names are proposed. Tofieldiales Reveal & Zomlefer, ord. nov. Based on a full and direct reference to the Latin description associated with a C. S. Kunth (Enum. P1. 4: 165. 17-19 July 1843, as sect. Tolfieldieae, nom. inval.: Art. 33.5) name. Nartheciales Reveal & Zomlefer, ord. nov. Based on a full and direct reference to the Latin description associated with a F. Parlatore (F1. Ital. 2: 360. 1852, as tribe Narthecieae) name. As here circumscribed, Tofieldiales is defined to include Tofieldiaceae, which is composed of Harperocallis McDaniel (1, Florida), Isidrogalvia Ruiz & Pavon (5, northern South America), and Tofieldia Hudson (15-17, Northern Hemisphere and Andes of South America; including Pleea Michaux). Nartheciales is defined to include only Nartheciaceae, a family of four genera: Aletris L. (15, eastern Asia and North America; including Metanarthecium Maximowicz), Lophiola Ker Gawler (2, eastern N rth America), Narthecium Hudson (7, Northern Hemisphere), and Nietneria Klotzsch ex Bentham (1, Guyana and Venezuela). Japonoliriaceae Takhtajan, which is restricted to the rare Japanese endemic Japonolirion Nakai (1, Japan), requires more work to assess its status and position. Acknowledgment. This work is supported in part by the Maryland Agricultural Experiment Station and Cooperative Extension Service. This proposal originated during work by the second author on the Generic Flora of the Southeastern United States, a long-term project funded by the National Science Foundation, currently supported by DEB9419940 (Walter S. Judd, principal investigator) and DEB-9419952 (Norton G. Miller, principal investigator). We thank Walter S. Judd for helpful comments on the phylogeny of the polyphyletic melanthioid complex.