Podostemaceae are aquatic angiosperms adapted to amphibious habitats in rivers. The flowers are produced when submerged in fast currents and unfold after exposure to the air. The floral morphology varies and provides diagnostic characters for recognizing three subfamilies. The flowers of subfamily Podostemoideae are characterized by a sac-like spathella enveloping flower buds and filiform ‘tepals’ that alternate with or are lateral to the stamens. In Tristichoideae and Weddellinoideae, the flowers are devoid of a spathella and the tepals are blade-like. To characterize these enigmatic floral organs, morphological, developmental, phylogenetic and genetic data were evaluated and floral development was examined in a few species of Podostemoideae and Weddellinoideae. All developmental, morphological and genetic data indicate that the spathella is a transformed tepal and what has been referred to as tepals are staminodes. Accordingly, the stalk above the spathella is an androgynophore. It uplifts the ‘tepals’ (= staminodes), stamens and pistils, while the ruptured spathella remains at the base. The spathella of Podostemoideae separates the protective and reproductive phases more distinctly than do the tepals in the other subfamilies. This flowering mode may be adapted to the habitat.
A new species of Carex sect. Paniceae (Cyperaceae) is described based on specimens from Honshu, Japan, and named C. nasuensis. It is similar to C. filipes and C. macroglossa, but differs from C. filipes in having pale green staminate scales, pale brown basal part of the sheath and perigynia tapering to the apex, and from C. macroglossa in having fewer (2–4) perigynia per pistillate spike, pistillate spikes more distantly located on the culm (3.6–7.5 cm between the uppermost and second uppermost pistillate spikes), flat or slightly elevated surface of the epidermal cells of the perigynium (without any conspicuous projections) and an achene epidermal cell surface with a small conical silica deposit surrounded by a marginal depression. A phylogenetic analysis based on the combined data set of plastid regions atpB–rbcL, rpl16–rpl16–rps3, rps16, matK and trnL–trnL–trnF and nuclear regions ITS and ETS (p = 0.41 in ILD test) indicated that C. nasuensis was distinct from both C. filipes and C. macroglossa, supporting the recognition of C. nasuensis as an independent species.
Betula ovalifolia Rupr. (Betulaceae) is a dwarf birch broadly distributed in northeast Asia, but in Japan limited to two mires in Hokkaido where it is endangered because of drying habitats due to open ditches. Moreover, putative hybrids between B. ovalifolia and a congener grow along the ditches, suggesting the risk of genetic pollution and extirpation of B. ovalifolia. We aimed to elucidate the parental species of the hybrids, to develop species-specific PCR primers to cost-effectively identify hybrids without DNA sequencing, and to examine using the primers whether hybrids invade the mires. Sequencing of nrDNA ITS revealed that the parental species were B. ovalifolia and the allopatric B. ermanii, not B. platyphylla, which inhabited the same ditches. The developed primers successfully amplified the DNA of the parental species and the hybrids with a low enough error rate to screen the hybrids. PCR using the primers indicated that six of eight putative individuals were hybrids while the other two were atypically tall individuals of B. ovalifolia. Exfoliating twig bark was a diagnostic characteristic of the hybrids. Tests for hybrids using the primers showed no evidence of hybrids inside the mires. The hybrids have the same parents as the endangered Hokkaido endemic, B. apoiensis, but the hybrids in the ditches are the consequence of human disturbance and are thus considered to have no conservation value.
New localities for Chionoloma orthodontum (Pottiaceae) are reported from Japan. The species is characterized by its narrow leaf base with a V-shaped cell pattern, the excurrent costa forming a short mucro and the presence of rhizoidal tubers. Based on Japanese material, a full description, analytical illustrations, and ecological information are provided. The phylogenetic position of the Japanese plants is inferred on the basis of chloroplast atpB–rbcL, trnG and trnL–F sequences.
A new variety of Allium schoenoprasum L. (Amaryllidaceae), var. tangoense G. Ito, Fuse & M. N.Tamura, is described based on specimens collected on Kyogamisaki Cape, Kyotango-shi, Kyoto Pref., western Japan. Allium schoenoprasum var. tangoense is similar to A. schoenoprasum var. orientale, but differs from it in having a fresh, white tunic covering an ovoid bulb and pale purplish pink tepals. Further, the flowering period of var. tangoense is about two or three weeks later than that of var. orientale around the native habitats of var. tangoense.
It is well documented that some mycoheterotrophic plants have distinct intraspecific color variations. Although a blackish brown color is typical of the mycoheterotrophic Gastrodia pubilabiata (Orchidaceae), a dark green variant from Aichi Prefecture, Japan, is reported here. The dark green variant differs from typical plants only in color. Therefore, a new form, G. pubilabiata f. viridis, is proposed.
Leymus komarovii (Roshev.) J. L. Yang & C. Yen (Triticeae, Poaceae) is a rare species in Japan, reported only twice from Hokkaido. In 2018, an additional specimen of L. komarovii was collected in Oketo-cho, Tokoro-gun, Hokkaido. Subsequent examination of specimens in Japanese herbaria revealed that its distribution range in Hokkaido was wider than previously known. Asperella longearistata (Hack.) Ohwi f. glabra Ko. Ito, described from Hokkaido, is reduced to synonym under L. komarovii and a lectotype for Hystrix sachalinensis Ohwi, another synonym of L. komarovii, is designated, superseding a previous lectotypification. A detailed description of L. komarovii based on Japanese materials and a key to the Japanese taxa of Leymus is provided.
We here report Aristolochia faviogonzalezii T. V. Do, Wanke & Neinhuis and A. versicolor S. M. Hwang (Aristolochiaceae) as two newly recorded species for the flora of Lao PDR. To facilitate identification, a key to the seven species of Aristolochia in Lao PDR is provided.
Rodgersia aesculifolia Batalin var. henrici (Franch.) C. Y. Wu ex J. T. Pan (Saxifragaceae) is reported for the first time from India. It occurs in a temperate forest in Kiphire District, Nagaland, NE India.