Freshwater aquaculture

Practical 5 - Study of aquatic weeds

5.2. Submerged Weeds

Hydrilla

• Stem slender, grows up to 0.5 m in length
• Can infest water even 12m in depth
• Common in India
• Leaves are linear
• Flowers during October to January
• Grows fast
• Reproduces by vegetative propagation
• One of the important ornamental plant
• Causes problems in fish ponds
• Grass carp feeds on this weed

Vallisnaria sp.

• Rooted to pond bottom.
• Leaves are linear and ribbon like and have sheath at the base.
• Grows up to 30 – 35 cm in length and 5-7 cm in width
• Dark green in colour
• Flowers during Oct. to March
• Ornamental

Ceratopyllum

• Perennial submerged rootless plant
• Sometime anchored to bottom by shoot
• Leaves finely divided and located in whorls at the nodes
• Grows up to 20cm in length
• Flowers from Jan to March

Cabomba sp.

• Submerged rooted plant with leaves placed opposite to each other.
• Structures looking like fans
• Stem slender with gelatinous line
• Good ornamental plant

Chara sp.

• Plant with whorls of short branches
• Attached to soil by rhizoids
• Flowers soft, encrusted with calcium deposits in hard waters
• Musk like smell when crushed

Nitella sp.

• Stem cylindrical
• Leaves arranged as Whorls at regular intervals

Myriophyllum

• Long and slender stem
• Pinnate leaves in whorls of 4-6
• Highly segmented
• Masses of stems detach and float