Correa lawrenceana Hook. is a widespread species in south-eastern Australia with eight recognised varieties. The Tasmanian variety, var. lawrenceana, is morphologically diverse. The present study uses multivariate morphometrics, including cluster, ordination and canonical discriminant analyses of samples of all recognised varieties of C. lawrenceana to assess whether more than one Tasmanian form warrants taxonomic recognition. These analyses showed that (1) var. lawrenceana can be divided into two well discriminated groups that are both endemic to Tasmania, a glabrescent form from the north-east and a hirsute form from the western, central and south-eastern regions, (2) the glabrescent form matches the type of C. lawrenceana and thus retains the name var. lawrenceana, and the hirsute form matches the type of C. lawrenceana var. ferruginea Hook.f. that is reinstated. The two varieties are separated geographically except in a small area around Deloraine in the north where intermediate morphological forms occur. The density of trichomes on the abaxial leaf surface is important for distinguishing the two Tasmanian varieties. An updated key to all varieties of C. lawrenceana along with descriptions of the Tasmanian varieties is presented. Nomenclature of the Tasmanian taxa is discussed and C. lawrenceana, C. lawrenceana var. glabra Benth., C. lawrenceana var. glabra L.Rodway and C. ferruginea Gunn ex Hook. are lectotypified.

Charophytes in the genus Lamprothamnium exhibit a large amount of diversity, particularly in the examples from Australia, although little of that variation has been recognised at species level in the past. The Australian members of the genus are revised here on the basis of extensive new collections, examination of specimens in herbaria and comprehensive review of the literature and available type material. The existing species Lamprothamnium macropogon (A.Braun) Ophel, L. inflatum (Fil. & G.O.Allen ex Fil.) A.García & Karol and L. heraldii A.García & Casanova are retained, eight new species are described (L. australicum Casanova, L. beilbyae Casanova, L. capitatum Casanova, L. compactum Casanova, L. coorongense Casanova, L. diminutum Casanova, L. macroanthum Casanova and L. stipitatum Casanova) and two taxa variously treated at infraspecific rank in Lychnothamnus are transferred to Lamprothamnium at species rank (L. cockajemmyense Casanova, L. tasmanicum (A.Braun) Casanova). Neither L. papulosum (Wallr.) J.Groves nor L. succinctum (A.Braun) R.D.Wood are confirmed for Australia after examination of the type material of these species. Species are distinguished by the arrangement of the gametangia, morphology of the fertile whorls and characteristics of the oospores. Four of these species are dioecious and nine are monoecious, which supports published conjectures concerning the biogeography of charophyte species (Proctor (1980): J. Phycol. 16, 218–233, doi:10.1111/j.1529-8817.1980.tb03023.x).

Taxonomic circumscriptions of the charophyte taxa Chara fibrosa C.Agardh ex Bruzelius. and C. flaccida var. wightii A.Braun are revised, and both taxa are recognised at species rank, as C. fibrosa and C. wightii (A.Braun) Casanova. Both species are illustrated and a review of relevant morphological characters is also presented.

Various published hypotheses regarding circumscription and relationships of species within the Radula parvitexta and R. ventricosa species groups were tested using molecular data from three chloroplast markers. The phylogeny resolves five clades within the R. parvitexta species group in Australia, which proves polyphyletic across two subgenera, or three subgenera if R. madagascariensis is included. One clade represents an undescribed species, R. psychosis sp. nov., one corresponds to R. madagascariensis, a new record for Australia, the others to R. ratkowskiana, R. tasmanica and R. robinsonii. R. ratkowskiana is reinstated from synonymy of R. tasmanica, and R. parvitexta is placed into synonymy of R. robinsonii. A second new species belonging to the R. parvitexta species group, R. kilgourii sp. nov., is described; however, it was not included in the phylogeny. Three clades were resolved within the R. ventricosa species group in Australia, which is nested within subg. Metaradula. These clades corresponded to R. jovetiana, R. loriana, which is reinstated from synonymy of R. ventricosa, and two new species, namely, R. myriopoda sp. nov. and R. forficata sp. nov. R. ventricosa is excluded from the Australian flora, because all material is referrable to R. loriana. R. forficata and R. kilgourii had not been collected before the present study. R. myriopoda and R. jovetiana exhibit overlap in morphology of the sterile gametophyte and can be reliably separated only on characters associated with the perianth mouth. They can be considered semicryptic species, and would not have been recognised independent of fieldwork and molecular investigations conducted as part of the present study.