Persicaria decipiens (Slender Knotweed / Water Pepper)

Persicaria decipiens is a versatile Australian native herbaceous plant, typically decumbent to ascending, growing up to 30 cm high. It thrives in damp soils along creek banks, wetlands, and moist open areas, often forming dense mats.

The narrow-elliptic to lanceolate leaves are 5–12 cm long and 5–13 mm wide, often displaying a distinctive purplish blotch near the middle of the upper surface. The lower surface may occasionally have scattered sessile glands, while veins and margins are softly pubescent. Leaves arise from short petioles 0–7 mm long, and the plants feature ocrea with cilia 2–10 mm long.

Persicaria decipiens produces slender, elongate-cylindrical spikes 2–6 cm long and 3–4 mm wide, with small perianth segments 1.7–2.5 mm long. It forms lenticular to trigonous achenes, 1.5–2.0 mm long, dark brown to black, making it a low-growing, attractive plant for water-edge gardens and dampland restoration projects.