Australian Journal of
Taxonomy
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Type: New South Wales. Northern Tablelands: Mt Lindesay Highway, 2 km S of Boonoo Boonoo, 2 February 2023, A.R. Bean 35252 (holo: BRI; iso: CANB, MEL, NSW).
Figure 5. Hydrocotyle maculosa. a. leaf, upper surface b. leaf, lower surface c. glands on upper leaf surface d. fruits (a,b,c from Bean 5854; d from Bean 8228).
Stoloniferous herb (to 50 cm high when supported by adjacent vegetation); stems filiform, glabrous. Stipules orbicular or broader than long, 1.3–1.5 x 1.2–1.5 mm, white with reddish-brown mottling; margin entire. Petioles of fully developed leaves terete, 45–90 mm long, inserted at base of lamina; petiole hairs few at distal end, 0.4–1.0 mm long, retrorse, brown. Lamina orbicular-cordate, radius 7–14 mm, with 6–8 major palmate veins; margin with 5–7 shallow lobes, each lobe crenate to crenulate; radius at major sinuses 67–85% of lamina radius; upper surface glabrous, punctate with many minute reddish glands < 0.1 mm apart; lower surface glabrous. Inflorescence umbellate, 7–13-flowered; all flowers bisexual; peduncles 4–10 mm long, much shorter than the adjacent petiole, glabrous. Involucral bracts 10–20, spathulate, 0.6–0.9 mm long; pedicels 0.2–0.4 mm long; petals purple or white, c. 0.9 mm long, anthers c. 0.25 mm long. Schizocarps symmetrical, strongly compressed; mericarps 2, 0.8–0.9 mm long, 0.55–0.7 mm wide, brown, glabrous, sometimes glandular; dorsal ribs not winged; lateral ribs prominent. Fruiting styles 0.4–0.5 mm long; style base swollen. Fig. 5.
Specimens examined: Queensland. Darling Downs district: Watson’s Swamp, 6 km N of Amiens, 27 Mar 1993, A.R. Bean 5854 & P.I. Forster (BRI, CANB); near Racecourse Creek, Mt Norman road, Girraween National Park, 2 Feb 2023, A.R. Bean 35261 (BRI, P). New South Wales. Northern Tablelands: 7.3 km by road SW of Tenterfield, 8 Dec 2003, A.R. Bean 21264 (BRI); 2 km S of Boonoo Boonoo, 16 Dec 1990, A.R. Bean 2806 (BRI, CANB); Silent Grove-Torrington road, 19.1 km N of Torrington, 27 Jan 1995, A.R. Bean 8228 (BRI, NSW).
Figure 5. Hydrocotyle maculosa. a. leaf, upper surface b. leaf, lower surface c. glands on upper leaf surface d. fruits (a,b,c from Bean 5854; d from Bean 8228).
Distribution & habitat. Only known from the Stanthorpe area of Queensland, and adjacent areas on the Northern Tablelands of New South Wales (Fig. 1). It is apparently confined to poorly drained swampy areas dominated by sedges (Cyperaceae) and restiads (Restionaceae).
Etymology. From the Latin maculosus, meaning ‘spotted’. This is in reference to the many small spots on the upper surface of the leaf lamina in dried specimens of this species (Fig. 5c).
Notes. Hydrocotyle maculosa is clearly allied to H. fontana but differs by the petiole hairs being confined to the apex (petioles hairy throughout for H. fontana), the lower leaf surface glabrous (hairy throughout for H. fontana), the 7–13 flowers per inflorescence (15–22 flowers for H. fontana), the peduncles 4–10 mm long (10–21 mm long for H. fontana), and the mature fruits 0.8–0.9 mm long (0.6–0.7 mm long for H. fontana).
Hydrocotyle maculosa differs from H. dipleura by the leaf laminae with radius 7–14 mm (2–7 mm radius for H. dipleura), petioles 45–90 mm long (6–20 mm, rarely to 50 mm long for H. dipleura), stipules entire (stipules deeply laciniate for H. dipleura) and mericarps with a single lateral rib (two lateral ribs for H. dipleura). Their habitats are also quite different, as H. dipleura is confined to the dried-out margins of artesian springs.
The reddish glands on the upper surface of the lamina are conspicuous in dried herbarium material, but only faintly visible in fresh material.