Callitriche brachycarpa Hegelmaier 1868

3. Callitriche brachycarpa Hegelmaier (1868:115). Type: AUSTRALIA. VICTORIA. tributary of the Plenty towards Mt Disappointment, 6 February 1853, F. Mueller s.n. (Lectotype [designated by Bean 2007: 547] STU 83916; Isolectotypes: MEL 50295 & 50296). Description: —Stem and leaf scales present. Leaf bases connate. Lingulate leaves unknown, expanded submerged or floating leaves unknown; leaves of terrestrial plants obovate, 1.6–7.0 mm long × 0.7–5.0 mm wide, 3-nerved, sometimes with free veins from the midrib, as well as free and looped veins from the outer nerves. ♂ ♀ flowers usually in the same axil. Bracts linear, hyaline, caducous, 0.3–0.5 mm long. Styles persistent, erect, 1.2–1.5 mm long. Filament erect, 0.5–2.5 mm long; anthers 0.2–0.3 mm long × 0.2–0.3 mm wide, possibly trilocular; pollen yellow. Fruit not strumose, subsessile, wider than high, light brown to blackish when mature, 0.6–1.0 mm long × 0.8–1.3 mm wide, narrowly winged throughout. Illustrations: — Figures 4 (a–b) and 4A(a–b) in Mason (1959). Fig. 1c. Recognition: — C. brachycarpa can be distinguished from other Callitriche species in the region by the combination of the small, unwinged, sessile fruit which is blackish when ripe, and ± isodiametric or wider than high and not umbonate, together with most leaf axils containing both ♀ and ♂ flowers. Distribution: —Native. Callitriche brachycarpa is endemic to Australia, where it occurs throughout the western lowlands and on King Island in Tasmania (Fig. 3). It is also known from six locations across Victoria State; three on the Otway Coast and three in the Port Phillip area (Curtis and Morris 1975, Parks Victoria 2000, Aston 1973). It formerly occurred at a site subject to inundation on the northern outskirts of Melbourne (Jeanes 1999, Bean 2007, Threatened Species Section 2012) but has apparently been lost from this site. Habitats and Ecology: — Callitriche brachycarpa occurs in creeks and rivers or in damp hollows (Bean 2007), often in or near wet forest, but also in moist areas of dry sclerophyll forest and riparian scrub. It has been recorded with a range of Eucalyptus L’Hér. (1788: 18) and Olearia species, as well as species such as Acacia dealbata Link (1822: 445), Atherosperma moschatum Labill. (1806: 74) and Nothofagus cunninghamii Oerst. (1873: 355). There is no information available on the elevation range of C. brachycarpa. Notes: —H.D. Schotsman took extensive notes which accompany the specimen HO 34457 suggesting that the anther of this species is trilocular. However, this requires confirmation based on fresh material. Conservation Status: — Callitriche brachycarpa is very poorly-known throughout its range, with no recent data on the conservation status of populations. It is therefore classed as Data Deficient. Additional material studied:— AUSTRALIA: TASMANIA. s.d., s.coll. s.n. (NSW 33820); Gippsland, February 1877, F. von Mueller 250 (NSW 33821); Nr. Martin, 1881, F. von Mueller s.n. (G); Picton River December 1903, L. Rodway s.n. (HO 72958, HO 8145); Kindred, January 1910, L. Rodway 250 (HO 72956, HO 8147); Forth River, December 1911, L. Rodway s.n. (HO 34457, HO 72959); Fisherman’s Varna Bay, 25 January 1984, A. M. Buchanan 2773 (HO 83798); Jackeys Creek, 2 March 1986, A. Moscal 12540 (HO 403083).Published as part of Lansdown, Richard V., 2022, The genus Callitriche (Plantaginaceae, Callitricheae) in Australasia and Oceania, pp. 243-284 in Phytotaxa 547 (3) on pages 249-250, DOI: 10.11646/phytotaxa.547.3.3, http://zenodo.org/record/657753