Rhododendron sect. Brachycalyx (Ericaceae) is diverse in Japan, and is known as a taxonomically difficult group because of extensive speciation and occasional hybridization, mostly coetaneous or precocious nature, and inadequate description of many taxa mainly based on limited herbarium specimens. This paper is a revisional work of Japanese taxa of the sect. Brachycalyx mainly based on the first author’s examination of living materials in the field throughout Japan for nearly 50 years together with many herbarium specimens, allowing sufficient characterization of every member. Taxonomic history of Japanese sect. Brachycalyx species is reviewed. Useful characters in habits, winter buds, flowers, capsules and leaves are extracted, not only for delimitation of taxa but also estimation of interspecific relationships and recognition of hybridity. Distribution of stipitate glands on vegetative and/or reproductive organs and their viscidness are regarded as important characters. In this study 18 species including two new ones are recognized and classified into eight series. Two new taxonomic states from variety to subspecies are proposed, two species, a subspecies, 10 varieties and five forms are newly described. A key to Japanese taxa of Rhododendron sect. Brachycalyx based on flowering and fruiting materials, and synoptical enumeration on all recognized taxa in each series as well as their distinction, distribution, and ecological notes will be described in the next paper.

The genus Desmodium is polyphyletic as suggested by recent molecular analyses. Desmodium sections Nicolsonia and Sagotia constitute a monophyletic group distinct from that which includes Desmodium scorpiurus, the type of the genus. The oldest generic name applicable to the monophyletic group is Grona Lour. It was established on the basis of Grona repens Lour. (= Desmodium heterocarpon (L.) DC.) in 1790, but the name is rejected under the conserved name Desmodium Desv. published in 1813. Desmodium and Grona in a new sense are separated from each other based on morphological and palynological characters and evidence from molecular analyses. Grona is, therefore, resurrected in order to accommodate the species belonging to Desmodium sections Nicolsonia and Sagotia under ICN Art. 14.6. The present paper provides 41 new specific combinations with 13 new infraspecific combinations under Grona.

Fimbristylis campylophylla Tuyama with its variety, var. pygmaea Tuyama, has been treated by recent botanists as F. diphylloides Makino or its variety. As a result of my morphological and ecological studies, F. campylophylla is considered as distinct from F. diphylloides and F. campylophylla var. pygmaea is inseparable from F. campylophylla var. campylophylla. Fimbristylis drizae J. Kim & M. Kim described from Korea should be reduced to a synonym of F. campylophylla. Fimbristylis campylophylla is widely distributed in Japan and is newly found in Korea.

Six new forms of the Fritillaria japonica group (Liliaceae) with unusual flower color, belonging to sect. Japonicae (‘Kobaimo’ in Japanese) are described. They are F. amabilis Koidz. f. moritae Naruh., F. ayakoana Maruy. & Naruh. f. yadae Naruh., F. japonica Miq. f. tamagawae Naruh., F. koidzumiana Ohwi f. takahashii Naruh., F. muraiana Ohwi f. takedae Naruh., and F. shikokiana Naruh. f. yamadae Naruh.

Oxygraphis kamchatica (DC.) R. R. Stewart (Ranunculaceae) based on Ranunculus kamchaticus DC. is reported here as having priority over Oxygraphis glacialis (Fisch. ex DC.) Bunge based on Ficaria glacialis Fisch. ex DC. and hence the correct choice as accepted name at the species rank.

Radula cavifolia Hampe ex Gottsche, Lindenb. & Nees is reported for the first time from Anjaw District of Arunachal Pradesh, India. The description and illustration based on Indian plants are given. The species is characterized by extremely small plants with normal and stylar branching, 4–5 cells thick stem with yellowish brown, thick-walled cortical and medullary cells with conspicuous trigones, and orbicular, strongly concave, subequally bilobed leaves.

Arisaema angustatum Franch. & Sav. and A. pseudoangustatum Seriz. var. pseudoangustatum (Araceae) were found at Ohgaya, Nishiawakura-son, Aida-gun, Okayama Pref., western Japan. This is the first report for these species from Okayama Pref.