: European waterstarwort
: Difficult to distinguish from other Callitriche species unless fruit is present; survey in late summer and fall. It can be distinguished by its fruits, which are almost round (orbicular).
: Aquatic; perennial, delicate.
: Tiny, opposite, entire, forms vary, floating leaves spatulate, submergent leaves linear.
: 10-30 cm (4-12 in) in length, usually branched, rising to surface or sprawling.
: Tiny flowers lack sepals and petals and are located at the leaf bases on minute stalks, 2-4 tiny whitish bracts emerge from the flower base.
Fruit and seeds
: Small, located at the leaf bases. Four compartments, each containing one seed. Pond: Oval, 1.2-1.8 mm long, 1.2-1.7 mm wide, narrow margin all around (wing); bracts at base. Autumnal: 1.1 to 1.6 mm long, 1.2 to 1.8 mm wide, no margin, fruit without bracts.
: Native to Europe. Found in shallow waters of pond, marches or in protected areas in lakes or streams with slow-moving water.
: By seed and clonally, dispersed by boats, vehicles, and animals-the latter both by fragments and ingested seed. Not all produce seeds.
: Hard to distinguish from other water-starworts (Callitriche spp.
) when not in fruit.
Monitoring and rapid response
: Hand-pulling, cutting or raking making sure to remove all fragments. Clearing off boats and other water-related equipment will help prevent spreading.
: The Michigan Natural Features Inventory
(MNFI) has partnered with MISIN to provide the information in this fact sheet. Species images and/or information were used with permission from "A Field Identification Guide to Invasive Plants in Michigan's Natural Communities
" and "A Field Guide to Invasive Plants of Aquatic and Wetland Habitats for Michigan