Botanical name: Ludwigia octovalvis Family: Onagraceae (Evening primrose family)
Synonyms: Ludwigia octovalvis subsp. sessiliflora, Ludwigia angustifolia
Willow Primrose is an erect, stout, well-branched robust herb of damp or flooded areas. It may be woody at the base and shrubby at times, growing up to 4 m. It has long stiff hairs sometimes appressed and oriented in one direction. Stems may be red-brown. Alternately arranged leaves are light green, may turn red upon aging, narrowly lanceshaped to ovate, up to 15 cm long, 0.4-4 cm wide, densely velvety both sides, narrowed at base and tip, 12- 22 veins on each side of midrib. Leaf-stalk is short. Sepals are 4, ovate or lanceshaped, 0.8-1.3 cm long by 1-7.5 mm wide. Flowers occur singly in leaf axils and at branch ends. Petals are 4, pale to bright yellow, 0.6-2 cm long, 0.4-1.7 cm wide, broadly obovate and may be shallowly notched at tip. Fruit is a thin-walled, 4-angled, narrowly cylindrical, 8-ribbed capsule, 3-5 cm long, 2-8 mm in diameter, velvety, terminated by persistent sepals, color by vary from green to pale or reddish brown, or purplish, stalk up to 1 cm. Willow Primrose differs from Water Primrose by its more erect habit and larger, lanceshaped leaves that are somewhat pointed.
The flower labeled Willow Primrose is ...