The taxonomic history of the Japanese cattail has been unfortunate. It was discovered by Miquel (Stafleu, 1966) who described this presumed endemic of Japan based on its relationship with T. orientalis C. Presl. (Miquel, 1867). For unclear reasons, Kronfeld (1889) and after him Graebner (1900), both treated Miquel’s species as a synonym of the latter, providing no explanation of their decision. Perhaps that was the reason why T. japonica has been widely forgotten taxon for decades. The other reason of such forgetfulness may be rooted in the writings of Miquel himself, who had established T. japonica as the sole species of Typha collected in Japan, while also expressing doubts on its novelty (Miquel, 1870).

Seventeen years after its designation, the lectotype of T. japonica is still stored at the Leiden Herbarium under the name T. angustifolia L. (Fig. 2, left). This classification emphasizes the unique morphology of the Japanese cattail. In fact, morphologically, T. japonica is more similar to T. latifolia L. (sect. Ebracteolatae) than to T. orientalis or T. angustifolia (H. G. Hallier, in Fig. 2, left). In addition to the lectotype, Ohba et al. (2005) listed two syntypes of T. japonica: 1. “Textor [not found], In agris oryzariis submersis ins.[ulae] Kiusiu[Kiu Siu]” (Fig. 2, right). and 2. “Buerger [Pierot no. 851] (L 0328985)”.

In terms of the external morphology, T. japonica clearly differs from T. angustifolia, T. latifolia, and T. orientalis in the sharply narrowed base of the slightly keeled, narrow (≤10 mm) leaf blades (Miquel, 1867, p. 160: “Folia (culmo breviora?) anguste linearia …”, italics ours), as well as by harsh, normally long-lasting spadices. In addition, we found that T. japonica is different from both T. angustifolia and T. orientalis by its 4-cell pollen (1-cell in the others).