Taxonomic Changes in Carex (Section Scirpinae, Cyperaceae)

Abstract

Carex scirpoidea Michaux var. convoluta Ktikenthal and C. scirpoidea Michaux var. pseudoscirpoidea (Rydberg) Cronquist are herein recognized and elevated to subspecies, and Carex scabriuscula Mackenzie and Carex gigas (Holm) Mackenzie are treated as synonyms. During the course of preparing a treatment of Carex sect. Scirpinae (Cyperaceae) for a forthcoming volume of the Flora of North America, it has become necessary to publish a change of rank for two combinations and make a note of synonymy. Carex scirpoidea Michaux var. convoluta Ktikenthal and C. scirpoidea Michaux var. pseudoscirpoidea (Rydberg) Cronquist are herein recognized and elevated to subspecies, and Carex scabriuscula Mackenzie and Carex gigas (Holm) Mackenzie are treated as synonyms. Carex sect. Scirpinae is a group of North American sedges (except for one population of Carex scirpoidea subsp. scirpoidea that grows in Norway) that possesses a dioecious breeding system, unispicate inflorescence, and pubescent perigynia. The section includes Carex scirpoidea and its four subspecies (subsp. scirpoidea, subsp. stenochlaena (Holm) Love & Love and the two proposed herein), Carex curatorum Stacey from Utah and Arizona, and Carex scabriuscula from Oregon and California. Based on the results of a biosystematic study (Dunlop, 1990), Carex scirpoidea is recognized as a geographically wide-ranging species with four subspecies. Subspecies in C. scirpoidea are geographically based ecotypes that share a common chromosome number, possess similar achene micromorphology and leaf anatomy, interbreed in greenhouse experiments, and have the majority of morphological characters falling within the normal range for C. scirpoidea but differ morphologically in only a few characters. Here, I propose that C. scirpoidea var. convoluta and C. scirpoidea var. pseudoscirpoidea be elevated to the rank of subspecies as they satisfy the criteria mentioned above. Carex scirpoidea subsp. convoluta (Ktikenthal) D. A. Dunlop, stat. nov. Basionym: Carex scirpoidea var. convoluta Ktikenthal, in Engler, Pflanzenreich 38(IV: 20): 81. 1909. TYPE: U.S.A. Michigan: Thunder Bay Island, 18 July 1895, Wheeler s.n. (holotype, B destroyed; isotypes, BH, CAN, GH, MICH, MIN, MSC, NY, POM, US, VT). Plants caespitose, lacking short creeping rhizomes. Flowering shoots lacking the persistent sheaths and bases of the previous years' leaves, erect. Vegetative leaves to 23 cm X 1.8 mm. Subtending scales ovate, 2.4 X 1.2 mm. Perigynia ovate, 1.5-2.6 x 1-1.2 mm, tightly enveloping the fruits for the entire length and width. Fruits 1-1.5 mm X 0.6-0.9 mm. Plants flowering from May to July and fruit from late June to September. Carex scirpoidea subsp. convoluta occurs in alvar communities (glacial scoured limestone pavements with shallow soil) along the Bruce Peninsula and island shores of Lake Huron. This subspecies is restricted to Ontario and Michigan; subspecies scirpoidea also occurs inland infrequently in the Great Lakes region. Subspecies convoluta is geographically the most restricted subspecies of Carex scirpoidea and is distinguished by narrowly V-shaped leaves, especially of the flowering shoot, a strongly caespitose habit, and conspicuously more flowering shoots per plant than other subspecies. T ese narrow-leaved plants were first described as a variety of Carex scirpoidea by Kikenthal based on specimens collected by Wheeler in 1895 from Thunder Bay Island, Michigan. Isotypes are available of Wheeler's 1895, Thunder Bay Island, Michigan, collections since Kikenthal's Carex herbarium, presumably including the holotype of C. scirpoidea var. convoluta, was sent to Berlin (B) and was destroyed during World War II (Stafleu & Cowan, 1979). Carex scirpoidea Michaux subsp. pseudoscirpoidea (Rydberg) D. A. Dunlop, stat. nov. Basionym: Carex pseudoscirpoidea Rydberg, Mem. New York Bot. Gard. 1: 78. 1900. Carex scirpoidea var. pseudoscirpoidea (Rydberg) Cronquist, Univ. Wash. Publ. Biol. 17: (1): 325. 1969. TYPE: U.S.A. Montana: Spanish Basin, July 1896, Rydberg 3064 (lectotype, designated by Mackenzie (1935), NY). NovoN 7: 355-356. 1997. This content downloaded from 157.55.39.186 on Tue, 11 Oct 2016 04:32:51 UTC All use subject to http://about.jstor.org/terms