Pistia stratiotes
Classification:
Kingdom: Plantae
Class: Tracheophytes
Order: Asimatales
Family: Araceae
Genus: Pistia
Species: stratiotes
Pistia stratiotes is a genus of aquatic plant and is also called as water cabbage, water lettuce, Nile cabbage or shellflower because of its appearance.
Occurence: Its native distribution is uncertain but is probably pantropical. It was first discovered in Nile near Lake Victoria in Africa. It is now present in nearly all tropical and subtropical fresh waterways and is considered as an invasive species as well as a mosquito breeding habitat. They are also found in slow-moving rivers, lakes and ponds. This plant cannot grow in colder regions beyond the tropics of Cancer and Capricon. The species also require slight acidity in the water they thrive in.
Structure: It is a perennial monocotyledon with thick, soft leaves that form a rosette. The leaves are sword-shaped in some plants. It floats on the water surface, its roots hanging submerged beneath floating leaves. The leaves can measure between 2-15 cm long and are light green with parallel venation and wavy margins. The leaf surface is covered in short, white hair which form basket like structures that help trap air bubbles thereby increasing the buoyancy of the plant. The spongy parenchyma with large intercellular spaces in the leaves also help the plant to float.
The flowers are dioecious. They lack petals and are hidden in the middle of the plant amidst the leaves. The inflorescence includes one pistillate flower with one ovary and 2-8 staminate flowers with two stamens. Oval, green berries with ovoid seeds form after the fertilization is successful. The plant undergoes asexual reproduction and will propagate through stolons.
This species can be grown in water gardens to reduce the harmful algal blooms and eutrophic conditions. The plant in capable of controlling the growth of algae by restricting light penetration in the water column and competing for nutrients, with significant uptake of phosphorus and ammonia nitrogen.