Limnophila sessiliflora is a rooted, aquatic, perennial, herbaceous plant that grows up to 12 ft (3.7 m) tall. It is fast growing, grows new plants from fragments, and can exist in a variety of aquatic habitats.
Foliage
Leaves of this plant have two types of whorled polymorphic leaves. The submerged stems have dissected, dark green, lance shaped leaves up to 1.2 in. (30 mm) long with irregularly serrated margins. The emergent stems have flat shiny hairs and fine, needle like leaves up to 0.12 in. (3 cm) long.
Flowers
The small flowers are sessile and arise singly from the leaf axis. The violet, lavender, pink, or blue flowers have five fused petals that form a tube. The floral tube has two lips, which have distinct purple lines on the undersides. The five sepals are green and hairy. Sepals are from 0.16-0.2 in. (4-5 mm) long.
Fruit
The fruit is an ellipsoid capsule that can contain up to 150 seeds.
Ecological Threat
L. sessiliflora can shade out and out compete other aquatic plants. It can tolerate a wide range of growing conditions. L. sessiliflora is listed as a Federal Noxious Weed.