Annual submersed aquatic herb to 0.8 m long Leaves: opposite, stalkless, 0.3 - 2.8 cm long, 0.2 - 1.8 mm wide, widening to a 1 - 1.9 mm sheath at base, linear with an abruptly pointed tip, with 50 to 100 tiny teeth per side (may require hand lens). Flowers: either male or female, found on the same plant (monoecious), borne one to three in leaf axils, green, tiny. The 1.5 - 2.5 mm long male flowers have four-lobed beaks, and the 1.5 - 2 mm long female flowers have four-lobed stigmas and stout styles to 0.5 mm long. Fruit: achene-like, yellowish white with a hint of purple, 1.2 - 2.5 mm long, 0.4 - 0.6 mm wide, spindle-shaped (fusiform), dull, pitted in ten to twenty rows. Stems: slender, highly branched, 11 cm - 0.75 m long, 0.1 - 0.8 mm wide, rooting at the nodes.
Similar species: Other subspecies of Najas guadalupensis differ from this subspecies by having longer styles (0.7 - 1.5 mm) and seeds with 30 - 60 rows of pits.
Flowering: early summer to fall
Habitat and ecology: Occasional in shallow water of ponds and lakes.
Occurence in the Chicago region: native
Etymology: Najas comes from the Greek name for a river nymph, naias. Guadalupensis means "from Guadalupe Island, Mexico."