Ludwigia hyssopifolia (G.Don) Exell

Exell, A.W. (1957) Garcia de Orta 5 : 471.

Seedbox

Occasionally grows into a shrub 2-3 m tall but usually flowers and fruits as a herb.

Leaf blades about 5-8 x 1.5-2 cm, petioles very short or absent. Stipules reddish, very small, about 0.25 mm long. Lateral veins forming definite loops inside the blade margin. Stems and twigs somewhat 4-angled with a pair of wings running down the stem from each petiole.

Sepals lanceolate. Petals about 2-3 mm long. Stamens eight, four long alternating with the petals and four short opposite the petals. Ovules produced in pairs in the upper part of each locule while the lower ovules are produced singly but encased in corky tissue.

Fruit about 1.5-3 cm long, slender and terete. Sepals persistent at the apex of the fruit. Two types of seed are produced in each capsule. Normal seeds are produced in the upper half of the capsule while the seeds in the lower half are contained in a 'corky seed carrier'.

Cotyledons +/- orbicular or broadly ovate, about 2-6 x 2-6 mm, petioles about 4.5 mm long. First pair of leaves opposite or subopposite, obovate, petioles long and slender. At the tenth leaf stage: leaf blade elliptic, apex acute, base attenuate, petiole narrowly winged. Stem narrowly winged with pairs of wings running down the stem from each petiole. Stipules small and inconspicuous, about 0.25 mm long. Seed germination time 17 to 108 days.

Occurs in WA, NT, CYP and NEQ. Altitudinal range from near sea level to 100-200 m. Usually grows in swampy situations in open forest but also found in swampy rain forest or on the margins of swamps near rain forest. Also occurs in Asia and Malesia, probably pantropic.