Identification: According to Radford et al. (1968), Thieret (1970), Barrett and Strother (1978):
Habit: annual wetland emergent herb/forb, growing on wet soil or in shallow water
Stems/roots: prostrate to erect, pubescent to strigose, 1-4 dm long or tall, rooting in soil
Leaves: 10--23 mm, generally obovate to elliptic, entire palmately 5-13 veined
Flowers: short-pedicellate 0-25 mm, bractlets absent, glabrous to pubescent, solitary or paired in leaf axils. Sepals 4 (5), 3-4 mm long, corolla white or tinged with pink, campanulate, 3-4 mm long, lobes slightly shorter than the tube, stamens 4
Fruits/seeds: ellipsoid to oval fruits 2-3 mm long and ± 1.5 mm wide, tipped with persistent styles. Seeds are 0.4-0.5 mm long, 0.2 mm wide, cylindric to ellipsoid, brown yellow and reticulate
Look-a-likes: Other Bacopa species with white flowers include Bacopa monnieri (smooth water hyssop, native) which has obovate to oblanceolate 1-veined leaves and is entirely glabrous, Bacopa rotundifolia (disk waterhyssop, native) has orbicular glabrous leaves and Bacopa stricta (yerba de culebra, native to Puerto Rico) which has serrate oblanceolate leaves
References: (click for full references)
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This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.