Invasive Alien Species

Species Name: Hydrilla verticillata

Family Name:
Hydrocharitaceae
Synonym:
Origin:
Not clear perhaps southern, southeastern Asia  and Australia.
Description:
Submerged freshwater plants, 25-300 cm long, profusely rooting in the mud, often with subter4ranean stolons with swollen top, densely covered with scales, 4-5 x 2.5 – 6 mm.  Stem are distinctly divided into nodes and internodes, and may be up to 5 5 m long in deep water. Leaves in whorls of 3-8, linear to ovate, sharply dentate, 8-40 mm x 1-5 mm.
Flowers develop singly within spathes in leaf axils, usually one female flower or several male flowers together in the upper nodes, with long peduncle, white or reddish; the male spathes contain a single flower 3 mm across, which released from the spathe just before maturity and floats up to the surface. Fruit elongate, 2-6 seeded; seed dark brown. Axillary turions green are formed in theaxil of a leaf and stalk, 3-12 x 2-3.5 mm.
Invaded Habitat:
In ditches, pools, ponds, marshes, shallow, muddy rivers; often abundant; also in tidal waters.  It can go down 6-12 m, in which case, it will not reach the surface.  In turbulent waters the plant remains bottom-bound.  Lowland-irrigated, lebak and tidal rice fields.
Distribution:
Widespread throughout Indonesia.
Ecology:
The plant spreads mainly by vegetative reproduction, e.g. by stolons, tubers, turions and stem fragments.  Grow is strongly enhanced with increasing nutrient content of the water.  The plant accumulates a bank of tubers and turions in the soil that may persist for several years.  The plant usually dies back above-ground at the end of the growing season. Growing  from 0-2000 m alt.
References:
  1. Backer , C. A. & R. C. Bakhuizen Van Den Brink.  1965.  Flora of Java. N.V. P. Noordhoff. Groningen, Netherlands. 
  2. Budiman, A., M. Thamrin and S. Asikin.  1988.   Beberapa Jenis Gulma di Lahan Pasang Surut Kalimantan Selatan dan Tengah dengan Tingkat Kemasaman Tanah Yang Berbeda.  Dalam Prosiding Konferensi HIGI IX.  
  3. Soerjani, M.,  A. J. G. H. Kostermans & Gembong Tjitrosoepomo (Eds.).  1987.  Weeds of Rice in Indonesia. Balai Pustaka. Jakarta. 
  4. Swarbrick, J.T., C.M. Finlayson and A.J. Cauldwell.  1982. The Biology and Control of Hydrilla verticillata (L.F.) Royle. BIOTROP Special Publication No. 16.
  5. Weber, E.  2003.  Invasive Plant Species of the World.  A Reference Guide to Environmental Weeds.  CAB International Publishing