Submerged aquatic perennials .
Plants are genetically variable and highly plastic depending on environmental conditions.
Stems typically grow rooted in the substrate, but fragment easily into free-floating pieces that root at nodes. Fragments may start new colonies when carried elsewhere. Brazilian elodea and hydrilla can aggressively invade new aquatic environments, displace native aquatic vegetation by forming dense stands or large sub-surface mats, and alter the dynamics of aquatic ecosystems. Other detrimental impacts from heavy infestations can include water flow impediment in waterways, increased flooding, clogged pumps and boat propellers, diminished water clarity, reduced use of lakes and waterways for recreational activities, and economic loss. At publication time monoecious and female dioecious populations occur in California.