Plants totally submerged and rootless, often forming large mats. The leaves narrowly linear, up to 12 per whorl, each leaf finely dissected into linear segments with tiny teeth along the margin. The female flowers form an achene with 2 basal down-turned spines (horns). Another `plant` which might lead to this same ID is Chara which is actually a colonial algae which forms structures which appear similar to coontail due to their whorled linear `leaves.` Upon drying Chara is covered with a white alkaline crust and is very brittle.