Annual, glabrous or subglabrous, erect or prostrate herb, sometimes rooting at the nodes when growing in water.. Stipules united with petiole for most of its length, the free part abruptly contracted to a fine point; petioles as short as 5 mm. in the upper leaves, where they may be wholly fused with the stipules, up to 5 cm. long in the lower leaves; leaflets elliptic or obovate, cuneate at the base, acute, rounded, truncate or slightly emar-ginate at the apex, up to 17 by 10 mm.; teeth strongly developed, with subulate tips; main nerves 8–10 on each side, at 40°–60° to the midrib.. Inflorescences hemispherical, 3–16-flowered, up to 23 mm. across; peduncle up to 7 cm. long; bracts oblong, whitish, 1–2 mm. long, usually 2–3-toothed at the tip; pedicels up to 3 mm. long, ± erect in fruit.. Calyx sparingly pilose at the margins only; tube ± 2 mm. long, broadly campanulate, strongly 11-nerved, the commissural nerves undivided to the top; teeth ± 5 mm. long, gradually narrowing from the base, which is ± 1·5 mm. wide, with broad scarious margins.. Corolla purple; standard ± 9 mm. long, abruptly narrowed above the middle into an oblongtruncate down-curved tip.. Stamens rt 6 mm. long.. Ovules 3–8, usually 4–6.. Pod glabrous, 5–7 by ± 3 mm.. Seeds brown, oval, flattened, ± 2 by 1·3 mm.. Fig. 142/8, 9, p. 1017.
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