This tiny non-descript plant is easy to over-look. Once extreamly rare, it can now be found in thick mats along wet portions of Cienega Creek where it is responding well to habitat restoration efforts.
Thick patches of umbel along Cienega Creek can easily be mistaken for grass but the stalks are not flat like grass but rather round like spaghetti noodles.
Prohibited in Arizona, this plant is often found in pet stores and pond supply stores where it hitchhikes along with other water plants. Once in a pond or stream, it is very difficult to get rid of. This plant is considered a threat to Cienega Creek because of its prolific nature. It grows so densely that it chokes out open water denying sunlight to other plants and animals causing fish kills.
Hydrilla grows rapidly and eventually takes over shallow waters depriving the stream or pond of sunlight and oxygen.