We revised the Holarctic taxa of Ditrichaceae on the basis of both organellar DNA sequence data and morphological traits. After the removal of phylogenetically discordant elements related to Flexitrichum and Rhamphidium, the remaining representatives of the family cluster into three well‐supported lineages, which are recognized here as the reinstated family Ceratodontaceae and a more restricted Ditrichaceae with two subfamilies. Rhamphidium is segregated into a newly described family, Rhamphidiaceae; Aongstroemia gayana, Dicranella vaginata and Symblepharis krausei are combined under Rhamphidium, and the genus Strombulidens is tentatively moved to Rhamphidiaceae. Ceratodontaceae includes the genera Ceratodon, Cheilothela, Trichodon, and a newly described Pseudaongstroemia, which includes a single species, known earlier as Aongstroemia fuji‐alpina. The genus Trichodon is paraphyletically defined to include T. cylindricus, T. oblongus reinstated at specific rank, and a molecularly distinct lineage, which we were unable to distinguish morphologically from T. cylindricus. The monoicous genera of Ditrichaceae and the autoicous taxa of Ditrichum as previously understood are merged into a single genus, Pleuridium, which is segregated to Ditrichaceae subfam. Pleuridioideae stat. nov. A single genus is also accepted within Ditrichaceae subfam. Ditrichoideae, following the transfer of both Aongstroemia julacea s.str. and A. orientalis to Ditrichum. Ditrichum septentrionale is newly described based on material mostly from North Asia. Two ecologically specialized, putatively only locally distributed taxa are synonymized with more widespread taxa. Ditrichum plumbicola is placed into synonymy with D. lineare and similarly D. cornubicum is tentatively synonymized with D. macrorhynchum. The morphological delimitations of D. lineare, D. pusillum and D. macrorhynchum are clarified and emended.

The recent molecular phylogenetic study of the families Aongstroemiaceae and Dicranellaceae, which resolved the genera Aongstroemia and Dicranella as polyphyletic, indicated the need for changes in their circumscription and provided new morphological evidence to support the formal description of newly recognized lineages. Following up on these results, the present study adds another molecular marker, the highly informative trnK–psbA region, to a subset of previously analyzed taxa and presents molecular data from newly analyzed austral representatives of Dicranella and collections of Dicranella-like plants from North Asia. The molecular data are linked with morphological traits, particularly the leaf shape, tuber morphology, and capsule and peristome characters. Based on this multi-proxy evidence, we propose three new families (Dicranellopsidaceae, Rhizogemmaceae, and Ruficaulaceae) and six new genera (Bryopalisotia, Calcidicranella, Dicranellopsis, Protoaongstroemia, Rhizogemma, and Ruficaulis) to accommodate the described species according to the revealed phylogenetic affinities. Additionally, we amend the circumscriptions of the families Aongstroemiaceae and Dicranellaceae, as well as the genera Aongstroemia and Dicranella. In addition to the monotypic Protoaongstroemia that contains the newly described dicranelloid plant with a 2–3-layered distal leaf portion from Pacific Russia, P. sachalinensis, Dicranella thermalis is described for a D. heteromalla-like plant from the same region. Fourteen new combinations, including one new status change, are proposed.

Bassia scoparia is a widespread weedy species in the temperate regions of the world and is valued as a medicinal and ornamental plant. To date, the taxonomic concept of B. scoparia remains insufficiently studied due to a limited number of samples used in the previous phylogenetic analyses. To solve the taxonomy of the B. scoparia complex, we constructed a new phylogeny based on the nuclear ribosomal internal transcribed spacer (ITS), plastid intergenic spacer atpB-rbcL, and plastid region rpL16 intron sequences for numerous samples with diverse morphology. Our analysis revealed a close proximity and intermixed positions of the samples of the B. scoparia group with various morphology. Because of this polyphyly, we prefer to broadly delimit the species. An updated nomenclature of B. scoparia is provided including four new synonyms: Bassia angustifolia, B. littorea, Kochia albovillosa, and K. scoparia subsp. hirsutissima. In its new circumscription, B. scoparia encompasses populations with glabrous or variously hairy leaves and perianths. The original material of Kochia sieversiana, previously considered a species with hairy leaves and inflorescences, has the same diagnostic characters as in B. scoparia s.str. The correct name for more hairy-leaved plants is B. scoparia var. subvillosa. Plants with hairy perianths known as Kochia albovillosa and K. scoparia subsp. hirsutissima have a restricted distribution in Central Asia and South Siberia and have never been recorded as alien in other regions; they can be classified as a separate variety, B. scoparia var. hirsutissima. The ornamental variant of oblong or pyramidal shape may be called B. scoparia var. trichophila. Bassia scoparia is often confused with a similarly looking relative, B. indica, especially in North Africa, a region where secondary ranges of both species overlap. Phylogenetically, these species are sister groups; they share some morphological characters but have different primary distribution ranges. We traced a recent expansion of B. indica in the Mediterranean with the first record reported from the European continent (Spain) and uncovered various introduction pathways of the species in this region.