Pallavicinia
Terrestrial. Specialised asexual propagules absent. Thallus translucent green, prostrate, simple or furcate, with additional branching from abaxial midrib or differentiated into an erect stipe and a repetitively furcate frond section; margins completely entire or serrate throughout or confined to near apex, undulate. Rhizoids over all midrib abaxially when thallus prostrate or confined to base of stipe in erect species. Antheridia adaxially in two irregular rows on either side of the midrib of thallus or rarely scattered over the midrib (not in Victoria), superficial, covered by dentate scales in a single row on either side of midrib. Sporophytes on adaxial thallus midrib, surrounded by an involucre and a pseudoperianth; involucre a ring of laciniate-ciliate scales; pseudoperianth tubular, plicate near apex, with toothed or ciliate mouth; shoot calyptra thin, hidden within pseudoperianth. Capsule cylindric, bistratose, dehiscing by 4 valves; elaters 2- or rarely 3-spiral. Spores spherical, areolate or granulate, brown.
15 species, mostly throughout southern temperate to tropical regions, but with one widespread species also scattered throughout northern temperate regions and one species extending to Japan (Söderström et al. 2016); three species in Victoria.
The Victorian P. rubristipa Schiffn. has been confused with Jensenia connivens (Colenso) Grolle, endemic to New Zealand, due to both having dendroid habits of the thallus (Scott 1985; Schaumann et al. 2004). However, the involucre of Jensenia is cup-shaped and not deeply dissected into free scales like in Pallavicinia. Current phylogenies based on DNA regions show that some species of Pallavicinia, such as P. rubristipa, are closer related to Jensenia than to other Pallavicinia (Schaumann et al. 2004, 2005; Forrest et al. 2005; Mamontov et al. 2021). However, these phylogenies are either based on few regions or few species and relationships within this group requires confirmation from analysis of a more comprehensive sample of species sequenced for a greater number of regions.
Forrest, L.L., Schuette, S.W., Crandall-Stotler, B.J. & Stotler, R.E. (2005). A molecular study of the simple thalloid liverwort Jensenia (Marchantiophyta, Pallaviciniaceae). The Bryologist 108: 204–211.
Mamontov, Y.S., Vilnet, A.A. & Schäfer-Verwimp, A. (2021). On the taxonomy of the subfamilies Pallavicinioideae and Podomitrioideae of the family Pallaviciniaceae (Marchantiophyta). Arctoa 30: 159–169.
Schaumann, F., Pfeiffer, T. & Frey, W. (2004). Molecular divergence patterns within the Gondwanan liverwort genus Jensenia (Pallaviciniaceae, Hepaticophytina, Bryophyta). Studies in Austral temperate rain forest bryophytes 25. Journal of the Hattori Botanical Laboratory 96: 231–244.
Schaumann, F., Frey, W., Pfeiffer, T. & Stech, M. (2005). Molecular circumscription, intrafamilial relationships and biogeography of the Gondwanan liverwort family Pallaviciniaceae (Hepaticophytina, Bryophyta). Studies in austral temperate rain forest bryophytes 27. Plant Systematics and Evolution 252: 27–48.
Scott, G.A.M. (1985). Southern Australian Liverworts. Australian Government Publishing Service: Canberra.
Söderström, L., Hagborg, A., von Konrat, M., Bartholomew-Began, S., Bell, D., Briscoe, L., Brown, E., Cargill, D.C., Costa, D.P., Crandall-Stotler, B.J., Cooper, E.D., Dauphin, G., Engel, J.J., Feldberg, K., Glenny, D., Gradstein, S.R., He, X., Heinrichs, J., Hentschel, J., Ilkiu-Borges, A.L., Katagiri, T., Konstantinova, N.A., Larraín, J., Long, D.G., Nebel, M., Pócs, T., Puche, F., Reiner-Drehwald, E., Renner, M.A.M., Sass-Gyarmati, A., Schäfer-Verwimp, A., Moragues, J.S., Stotler, R.E., Sukkharak, P., Thiers, B.M., Uribe, J., Váňa, J., Villarreal, J.C., Wigginton, M., Zhang, L. & Zhu, R. (2016). World checklist of hornworts and liverworts. Phytokeys 59: 1–828.