Densely tufted perennial with very short rhizome. Culms erect, dark green, rigid, 30–150 cm high, each with c. 2–5 leaves and several mid to dark brown shining cataphylls toward base; pith dense, uninterrupted, permeated with vascular bundles (visible in transverse section). Leaf-blades pungent, terete, culm-like; pith similar to that of culms; auricles absent. Inflorescence usually dense, with several to many radiating major branches which are often obscured, flowers clustered toward the ends of the ultimate branchlets; primary bract erect and pungent, continuous with culm; prophylls absent. Tepals tinged reddish-brown in part, equal or subequal, 2.5–4 mm long, firm-textured for the greater part, the outer 3 mucronate, the inner 3 notched or truncate with wide membranous margins at the tip; stamens 6; anthers red, 1.4–2 mm long. Capsules usually golden-brown, darker in upper half, ovoid to ellipsoid, 4–6 mm long, with a rather conical apex contracting Â± abruptly to a mucro, c. twice as long as tepals; valves thick-walled, the outer faces concave in the upper part; seeds 1.3–2 mm long, with 2 ± equal curved appendages, giving the seed a contorted appearance. Flowers throughout the year but mostly spring–summer, ripe fruit can be found virtually all year.
*CVU, *DunT, *EGL, *EGU, *GipP, *Glep, *Gold, *GGr, *HNF, *HSF, *LoM, *MuF, *MuM, *MSB, *NIS, *OtP, *OtR, *RobP, *Strz, *VAlp, *VRiv, *VVP, *WaP, *Wim. Also naturalised WA, NT, SA, Qld, NSW, Tas. Native to Europe, Africa, the Americas. A very serious environmental weed (and proclaimed noxious weed in Victoria), Juncus acutus has invaded mine dumps, coastal flats, irrigation areas, and other low-lying and often saline areas.
|Bioregion||Occurrence status||Establishment means|
|Victorian Volcanic Plain||present||naturalised|
|Murray Scroll Belt||present||naturalised|
|Central Victorian Uplands||present||naturalised|
|Northern Inland Slopes||present||naturalised|
|East Gippsland Lowlands||present||introduced|
|East Gippsland Uplands||present||naturalised|
|New South Wales|