[Cal-IPC] Ecological impact, invasiveness: Limnobium spongia (South American spongeplant) is a perennial aquatic plant (family Hydrocharitaceae) found on the San Joaquin river and the Sacramento-San Joaquin delta. The spongeplant can form thick mats across the water causing problems for boats, fish, and water infrastructure. Limbnobium spongia can spread rapidly through quick seed production and vegetative growth. The small, floating seeds easily disperse once produced. Cal-IPC Rating: High (link added by Mary Ann Machi)

[gobotany.nativeplanttrust.org] Southeastern USA native: American spongeplant is native to the southeastern states. It has thick, spongy, floating leaves and thinner emergent leaves that lack the spongy tissue. After fertilization, the peduncle curves down, so that the developing fruit is pushed underwater. (link added by Mary Ann Machi)