Ludwigia alternifolia L.
Seedbox, Bushy Seedbox, Bushy Waterprimrose, Rattlebox
Ludwigia alternifolia var. alternifolia, Isnardia alternifolia, Isnardia aurantiaca, Ludwigia aurantiaca, Ludwigia macrocarpa, Ludwigia microcarpa, Ludwigia pruinosa, Ludwigia ramosissima, Ludwigia salicifolia
Bloom Time: Late spring to early fall
Ludwigia alternifolia is a multi-branched, yellow-flowered perennial with reddish-tinged stems clad with short-stalked, deep green leaves. It grows up to 4 feet (1.2 m) tall. Leaves are lance-shaped and up to 4 inches (10 cm) long. Solitary, bright yellow flowers, each up to 0.75 inches (1.9 cm), bloom on short stalks in the upper leaf axils from late spring to early fall. Flowers eventually give way to fruits, cubical capsules up to 0.25 inch (6 mm) long, each having an apical pore. Each capsule splits open when ripe to release the numerous seeds contained therein.
USDA hardiness zone 4a to 8b: from −30 °F (−34.4 °C) to 20 °F (−6.7 °C).
How to Grow and Care
This floating Ludwigia is native to Central and South America, where it can be found growing in stagnant waters and sections of riverine environments that are free of the current. It is a very common pond plant in warm climates or ponds in conservatories. Cultivation in an aquarium is a bit more complicated.
Above all else, this floating stem plant requires light. Even values in the higher range of what is possible over a planted aquarium are often not enough. Outdoor culture in a well-lit pond or tub is sometimes the only way to achieve satisfactory growth with this species. Heavy fertilization with macro-and micronutrients is essential (if enough light is available) to produce attractive growth. Yellow flowers form on the floating rosettes if the plant is achieving good growth.
Winter hardy to USDA Zone 10. In St. Louis, grow as an annual in containers covered with 6 to 18 inches (15 to 45 cm) of water in full sun to part shade. Plants can be difficult to overwinter indoors.
Although the usefulness of this species in the aquascape is markedly limited, its beautiful circles of reddish foliage can lend a unique texture to outdoor ponds. See more at: How to Grow and Care for Mosaic Plant (Ludwigia sedoides)
It is native primarily to marshes, wet meadows, and swamps from southern Quebec and Ontario to Kansas and south to Texas and Florida.
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