Ageratina riparia (Regel) R.M.King & H.Rob.

Asteraceae

King, R.M. & Robinson, H.E. (1970) Phytologia 19(4): 216

Creeping Crofton Weed; Mist Flower

Usually flowers and fruits as a herb but occasionally flowers as a shrub 1 m tall.

Leaf blades about 3-12 x 0.8-3 cm with about 6-10 teeth on each side. Underside of the leaf blade clothed in hooked hairs on the midrib and lateral veins only, upper surface glabrous. Petiole grooved on the upper surface. Twigs clothed in erect, light brown, hooked hairs.

Inflorescence a cymose panicle of heads each containing about 15-25 flowers. Heads about 5-6 mm diam., subtended by green bracts. Sepals represented by about 15 hair-like appendages. Anthers fused but the filaments free.

Fruits about 1-2 mm long, longitudinally ribbed, each rib with a line of hairs. Endosperm very thin and scanty.

Cotyledons orbicular, about 2-4 mm diam., petiole about 1-3 mm long. First pair of leaves opposite, margins toothed. At the tenth leaf stage: leaf blade narrowly elliptic, about 5 x 2 cm, apex acute, base attenuate, margins coarsely serrate, very sparsely hairy to almost glabrous. Petiole about 7 mm long. Seed germination time 10 to 49 days.

An introduced species originally from Central America, now naturalised in NEQ and in south eastern Queensland southwards as far as coastal central New South Wales. Altitudinal range in NEQ not known but collected at altitudes of 1000-1100 m. Grows in damp areas of disturbed rain forest or along roads in damp areas of upland and mountain rain forest.

This species may be poisonous, it may also have uses as a tanning agent.

Eupatorium riparium Regel, Gartenflora 15: 324 (1866). Type: Aus dem Garten der Herren Haage und Schmidt in Erfurt erhielt der Petersburger Garten das in Rede Stehende Eupatorium, das sehr wahrscheinlich aus.