Juncus dichotomus
Elliot Forked RushTufted, shortly rhizomatous perennial. Culms erect, 25–65 cm high, each with (1–)2–3 leaves and 1–3 cataphylls towards the base, becoming ridged when dry, mid green, glossy. Leaf-blades subterete, channelled, shorter than culms and (0.5–)0.5–1.3 mm wide, apex acute to acuminate, mid green, glossy; auricles obtuse, to 0.2–0.5 mm long, scarious to subcoriaceous. Inflorescence terminal, more or less diffuse, with flowers usually well spaced, occasionally subcongested (but not forming well-defined clusters); 1 leaf-like bract 2–10 cm long, longer than or equalling inflorescence (rarely shorter), 2–10 cm long; prophylls present. Tepals with broad green midrib when young, margins membranous, pale; outer tepals 2.8–3.7 mm long, acuminate; inner shorter than or subequal to the outer; stamens 6, anthers 0.3–0.6 mm long. Capsules tan to golden brown at maturity, ellipsoid, c. 2.6–3.5 mm long, obtuse and shortly mucronate, shorter than or subequal to the tepals; seeds c. 0.3–0.4 mm long, slightly asymmetrical, finely reticulate (discernible at high magnification), minutely apiculate at one or both ends, apiculus < 0.15 mm long. Flowers Apr.–May (2 records) and presumably earlier, seeds shed Apr.–May (2 records).
GipP. Also naturalised in Qld, NSW. Widely distributed in the east and south-east USA, Mexico; Central America; South America. Naturalised in New Zealand. In Victoria known from two collections, both from the edge of an artificial pond at Karkarook Park, at Heatherton, where growing with other weeds among planted Melaleuca sp.
Juncus dichotomus is a member of the taxonomically difficult and unresolved J. tenuis species complex, and it has at times been treated as J. tenuis var. dichotomus (Elliot) A.W.Wood (Zuloaga et al. 2008). More recently a new combination J. tenuis subsp. dichotomus (Elliot) F.Verloove & J.Lambinon has been published (2011). Readily separable from J. tenuis in having subterete leaves (leaves flat in J. tenuis), auricles scarious to subcoriaceous and 0.2–0.5 mm long (auricles very thin, up to 6 mm long in J. tenuis). Some botanists regard the Australian plants as representing J. cognatus Kunth (Wilson 2010), but most of the literature treats J. cognatus as being a taxononomic synonym of J. dichotomus, e.g. Barros (1953), Kirschner (2002), and Balslev & Duno de Stefano (2015). First collected in Victoria in 2007.
SpinningBalslev, H.; Duno de Stefano, R. (2015). La familia Juncaceae en Mexico. Acta Botanica Mexico 111: 61–164.
Barros, M. (1953). Las Juncáceas de la Argentina, Chile y Uruguay. Darwiniana 10(3): 277–460.
Kirschner, J. et al. (2002). Juncaceae 3: Juncus subg. Agathryon, Species Plantarum: Flora of the World Part 8. Australian Biological Resources Study, Canberra.
Verloove, F. (2010). Juncus dichotomus (Juncaceae) in northwestern Italy, a xenophyte new to Europe. Willdenowia 40(2): 173–178.
Verloove, F.; Landinon, J. (2011). The non-native vascular flora of Belgium: new combinations and a new variety. New Journal of Botany 1(1): 38–42.
Wilson, K.L. (2010). Genus Juncus. In: PlantNET, New South Wales Flora online, pp. –.
Zuloaga, F.O.; Moorone, O.; Belgrano, M.J. (2008). Catalogo de las Plantas Vasculares del Cono Sur (Argentina, Sur de Brasil, Chile, Paraguay y Uruguay). Missouri Botanical Garden Press, St Louis, Missouri. USA.