Plants of South Eastern New South Wales

Isotoma fluviatilis

Flowers and leaves. Australian Plant Image Index, photographer Murray Fagg, Australian National Botanic Gardens, Canberra, ACT 

Carpet (subsp. australis). Photographer Don Wood, Wadbilliga National Park

Carpet (subsp. australis). Australian Plant Image Index, photographer Murray Fagg, Yanunbeyan State Conservation Area near Captains Flat

Common name

Swamp isotome

Family

Campanulaceae

Where found

Moist sand or mud on the edge of streams, seepage areas, swampy ground, and in moist lawns.

subsp. australis:  Ranges, tablelands, ACT, and Western Slopes. Occasionally elsewhere.

subsp. borealis:  Mainly along the Great Western Highway between Sydney and Bathurst.

subsp. fluviatilis: Mainly Sydney area and west. Occasionally elsewhere.

Notes

Prostrate perennial herb, rooting at the nodes, often mat-forming, hairy or hairless. Leaves alternating along the stems, 0.2-1.5 cm long, 1–8 mm wide, margins almost entire to scalloped or toothed. Flowers bisexual (subsp. australis and subsp. borealis) or male and female flowers on different plants (subsp. fluviatilis). Flowers tubular with 5 lobes, the tube with a short slit or notch, white, pale blue, or rarely pinkish, with a deeper blue zone edging the yellow near the base of the lower lobes; tube 2–7 mm long; lobes 2–11 mm long. Flowers single. Flowering: late spring to summer.

subsp. australis:  Flowers bisexual. Corolla 6.5–15 mm long, blue, rarely pinkish; leaves 2–13 mm long, 1–7 mm wide; flower stalks 3–85 mm long. Corolla tube and lobes hairy inside. Difficult to satisfactorily separate subspecies australis from subsp. borealis.

All native plants on unleased land in the ACT are protected.

subsp. borealis:  Flowers bisexual. Corolla 6–10 mm long; leaves 5–12 mm long, 2–5 mm wide; flower stalks 5–40 mm long in flower, to 60 mm in fruit. Corolla tube and lobes hairy inside. Difficult to satisfactorily separate subspecies australis from subsp. borealis.

subsp. fluviatilis:  Male and female flowers on different plants. Corolla 4–7 mm long, the tube and lobes hairless inside. Leaves 5–15 mm long.

Family was Lobeliaceae.

PlantNET description of species and key to subspecies:  http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Isotoma~fluviatilis  (accessed 19 January, 2021)