AQUACTIC WEED Aquatic weeds can be broadly defined as unwanted and undesirable plants which grow and reproduce in an aquatic environment (Lawrence, 1966)
Classification of Aquatic Weeds Two groups of aquatic plants: – 1. Algae - simple plants without roots, leaves or stems. They reproduce by cell division, fragmentation, or by spore formation. – 2. Vascular plants - plants having roots, stems, leaves, and flowers. There are four classes - submersed, free-floating, rooted floating, emerged plants.
Aquatic Weeds - Algae Three types: – 1. Microscopic algae - single celled or colonial algae. Also referred to as Phytoplankton when suspended in water. During the daylight - give off oxygen, During night - remove oxygen. If overabundant - fish kill due to oxygen removal from water - referred to as an algal bloom - the result of too much fertilizer in pond.
Aquatic Weeds - Algae Three types: – 1. Microscopic algae – 2. Filamentous algae - thread-like filaments that form mats on surface of the pond. As algae photosynthesize, oxygen gets trapped in the body causing them to rise to the surface as clumps. Examples: - Spirogyra - bright green and slimy- Cladophora - cotton mat algae, due to texture - Pitophora - horsehair coarse
Aquatic Weeds - Algae Three types: – 1. Microscopic – 2. Filamentous – 3. Chara - looks more like a plant with leaves needle-like and arranged in whorls along the stem. Musky odor and gritty surface due to calcium deposits. Also called stonewort
Aquatic Weeds - Vascular Plants – Submersed Plants Four Groups: 1. Submersed plants - rooted to the bottom and completely submersed except for flowers which may extend above the water. Often referred to as moss. Identification based upon: * Leaf arrangement * Leaf shape