Citation: R. Br., Prod. Fl. Nov. Holl. 500 (1810).

Synonymy: Not Applicable

Common name: Australian gipsywort, water horehound.

Description:
Perennial with erect usually unbranched quadrangular branches to 1.5 m long and produced from an underground rhizome, with scattered simple hairs becoming glabrous; leaves subpetiolate, oblong-lanceolate to oblong-elliptic, 4-15 x 0.8-2.5 cm, tapering into a sharp point and with a slender cuneate base, coarsely serrate to serrately lobed, with scattered simple hairs above, gland-dotted below.

Inflorescence a thyrse without a distinct peduncle, with sessile cymose part-inflorescences with few to many flowers and subtended by leaf-like bracts becoming shorter towards the apex; sepals about half its length connate, 13-veined, 3.5-5 mm long, with a few papillae along the veins and margins together with scattered sessile glands, with 5 lobes each ending in a stiff spine; corolla white, broadly funnel-shaped, not 2-lipped, with lobes about one-quarter of the length of the tube, slightly zygomorphic, 4.5-5.5 mm long, with few sessile glands on the outside and hairy in the throat; with a broad dorsal lobe vaguely 2-lobed, 2 narrower lateral ones and one broad anterior one; stamens inserted at about the middle of the corolla tube, with only the anterior pair producing anthers; filaments unequal pairs, longer than the anthers, recurred at the apex and hairy towards the base; anthers broadly ovate in surface view, with 2 cells slightly diverging at the base, glabrous, exserted just above the throat; ovary on a thick disc, deeply 4-lobed, with a slender style inserted near the base, with a deeply 2-fid stigma exserted at about the level of the anthers.

Mericarps oblong-obovoid, c. 2 mm long, truncate, centripetally compressed and triangular in section, with the outer surface more or less concave and with a gradually raised margin, with the attachment scar at the base of the keel inside, usually densely covered with glands on the inside.

	Flowering branch and calyx.
Image source: fig. 553H in Jessop J.P. & Toelken H.R. (Ed.) 1986. Flora of South Australia (4th edn).

Distribution:  Grows in marshes or along streams often in a somewhat shaded position. S.Aust.: MU, SL, SE.   Qld; N.S.W.; Vic.; Tas. Conservation status: native Flowering time: Dec. — April.

SA Distribution Map based on current data relating to specimens held in the State Herbarium of South Australia

Biology: No text

Author: Not yet available