Targioniaceae
Terrestrial or rarely lithophytic, monoicous or dioicous with male and female plants similar size. Specialised asexual propagules absent. Plant comprising a simple or repetitively furcate thallus, sometimes also branching from abaxial surface. Thallus differentiated into tissue composed of walls of cells that bound air chambers adaxial to solid tissue dedicated to storage, deep green, becoming black to blackish-purple at margins, glabrous, without adaxial grooves; margins entire to crenate, plane; air chambers floored by photosynthetic filaments, in a single layer, defined by polygonal boundaries on adaxial surface, thinner than underlying storage tissue; adaxial epidermal cells hyaline, thin-walled with conspicuous trigones; air pores simple; surrounded by 2–3 rings of differentiated cells. Abaxial scales lunate or lunate-triangular, in 2 rows, with one lanceolate to ovate appendage, violet to black-purple, with slime papillae along margins. Oil cells in abaxial scales and scattered through all thallus tissues. Rhizoids present, without and with internal peg-like thickenings, between abaxial scales and along abaxial midline. Androecia warty discs at apex of abaxially-derived branch or leading thalli (not in Victoria). Sporophyte enclosed in involucre at thallus apex and displaced abaxially; pseudoperianth absent; calyptra present, delicate; involucre light (not in Victoria) to dark purple or black, ovoid, bivalvate, each valve tightly appressed against the other until spore maturity, when apart forming a narrow slit. Seta short. Capsule globose, unistratose, dehiscing by an irregular lid and valves; elaters present, 1–3-spiral. Spores circular in outline, on distal face convex and areolate, on proximal face flat with contorted ridges, light brown to reddish brown, shed singly.
One genus and eight species in North America, Argentina, Chile, Bolivia, Europe, Africa, India, China, New Zealand and south-eastern Australia (Söderström et al. 2016); one species, Targionia hypophylla L., in Victoria.
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.