Phylogeny and Taxonomy of Carex (Cyperaceae) in Japan I. C. sect. Rarae

Abstract

est genus in the Cyperaceae Juss. and one of the most widespread genera in the world. The genus is characterized by unisexual flowers and a gynoecium enclosed by a flask-like prophyll called a perigynium (Reznicek 1990, Starr et al. 2004). Kükenthal (1909) recognized four subgenera, Carex (subg. Eucarex Peterm.), Indocarex (Baill.) Kük., Primocarex Kük. [subg. Psyllophora (Degl.) Peterm.], and Vignea P. Beauv ex T. Lestib. Carex sect. Rarae C. B. Clarke, which is included in the unispicate subgenus Primocarex, consists of approximately 20 species distributed in Asia and Oceania (Kükenthal 1909, Kern & Nooteboom 1979, Egorova 1985, 1999, Tang et al. 2010). Ten species and two varieties are reported from Japan (Table 1) (Katsuyama 2015). Carex sect. Rarae is characterized by androgynous spikes and ovoid, glabrous, membranaceous perigynia with an emarginate beak (Ohwi 1936). Egorova (1985, 1999) subdivided Carex sect. Rarae into three subsections based primarily on perigynium and culm characteristics (Fig. 1A– D): Capitellatae (Meinsh.) Kük., Rarae T. V. Egorova, and Erostratae T. V. Egorova. Carex subsect. Capitellatae is characterized by sharply triangular culms (Fig. 1D) and inflated perigynia that lack rusty dots (Fig. 1B). The perigynium has 8–10 indistinct (or almost invisible) veins on the dorsal surface and a short to medium apical beak (Fig. 1B). Carex fulta, C. hakonensis, C. onoei, and C. uda are included in this subsection, although C. fulta has 2–4 exceptionally distinct Phylogeny and Taxonomy of Carex (Cyperaceae) in Japan I. C. sect. Rarae