Common name: Amazon Frogbit
Limnobium laevigatum (Humb. & Bonpl. ex Willd.) Heine APNI*
Description: Aquatic perennial with floating and emergent leaves; stoloniferous.
Leaves with lamina elliptic to widely elliptic, rarely obovate or reniform, 2–6 cm long, 0.8–4 cm wide; apex rounded, occasionally acute or mucronate, base cuneate to truncate, rarely cordate; with a thick layer of aerenchymous tissue on the underside; petioles of aerial leaves 26–270 mm long, not inflated, petioles of floating leaves 5–85 mm long, sometimes inflated; stipules to 22 mm long, sheathing the developing apex.
Male spathes containing up to 11 flowers; peduncles to c. 25 mm long; pedicels to c. 43 mm long; flowers greenish-white to yellowish, with 3 sepals and 3 petals; stamens 6 or very rarely up to 9, in 2 (3) whorls. Female spathe containing up to 3 greenish-white flowers; peduncle c. 2 mm long or absent; pedicels to 40 mm long at anthesis, becoming somewhat longer in fruit; sepals greenish-white, spreading; petals usually poorly developed or absent, but sometimes up to 3, (1–5.5 mm long); staminodes present; styles 3–6, divided.
Fruit berry-like capsules, ellipsoid, 1.7–5 mm diam., containing up to c. 100 seeds.
Distribution and occurrence:
Grows in small shallow freshwater bodies or swamps.
NSW subdivisions: *NC, *CC
Can be confused with Hydrocharis dubia in a non-flowering state. When the undersurface of the lamina has an orbicular or ovate pad of honeycomb-like aerenchymatous tissue smaller than and clearly delimited from the rest of the lamina then it is probably H. dubia. Limnobium has well-developed large-cell aerenchyma covering most of the leaf undersurface.
Text by S.F. McCune (2021)
APNI* Provides a link to the Australian Plant Name Index (hosted by the Australian National Botanic Gardens) for comprehensive bibliographic data
***The AVH map option provides a detailed interactive Australia wide distribution map drawn from collections held by all major Australian herbaria participating in the Australian Virtual Herbarium project.