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Marijuana: State Prohibited Weed | LC0280 |
Keith Turnbull Research Institute, Frankston
January, 1998 |  |
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Common Names
Marijuana, Indian hemp
Botanical Name
Cannabis sativa L. s.lat.
Status
Marijuana is one of only fourteen weeds proclaimed as State Prohibited Weeds in Victoria. This is the highest category to which a noxious weed can be allocated and is complementary to the status of marijuana in other Victorian legislation.
Origin
Marijuana is native to central Asia. Marijuana will grow in a variety of climatic conditions. Reports indicate that it is illegally grown in most of Victoria.
Description
An annual herb with erect, bushy form, with a growth height between 2 and 7 m. Male and female flowers are on separate plants. The male plants produce abundant pollen which is shed prior to the plant yellowing and dying. Female plants are dark green and continue to actively grow until all the seed has ripened, unless damaged by frost. Reproduction is by seed only.
Stems - slightly woody, simple or sparsely branched, 1 to 2.5 cm diameter, rough, hairy, resinous in the upper part of the plant.
Leaves - dark green and sparsely hairy on the upper surface, paler and more densely hairy below; hand-shaped, with 5 to 9 finger-like leaflets growing from the tip of a narrow 4 to 5 cm long leaf stalk, the leaflets with sharply toothed margins and prominent veins.
Flowers - green; male flowers on small, branched flower stalks, in the leaf axis with a tiny leaf opposite; female flowers in leafy spikes and clothed in sticky hairs.
Seeds - usually an olive-brown to yellow colour, sometimes with a dark mottled pattern when ripe; almost round in shape or oval, slightly flattened, with blunt edges.
Roots - a 30 to 100 cm long, multiple-branched taproot, with a dense layer of laterally spreading roots immediately below the soil surface to a depth of 20 cm.
Figure 1: Marijuana plant.
Life Cycle
Seeds germinate from mid-spring to early summer. Plants take about three months to reach maturity. Flowering occurs from mid-summer through to late autumn and then plants are usually killed by frost.
Dispersal
Without doubt humans are the major cause of spread of this plant. Marijuana is illegally grown for use as a recreational drug. There may be some wild escapes, attributed to birds or fruit being carried away with surface water runoff.
Figure 2: Marijuana seeds.
Chemical Control
No products are registered in Victoria to control this weed.
Important
Any person who believes they have located marijuana plants should notify the police.
Reference
Parsons, W.T. and Cuthbertson, E.G. (1992) Noxious Weeds of Australia. Melbourne, Inkata Press
Acknowledgements
Drafted by N Freeman, edited by R Williamson, KTRI, 1996. Updated by I. Faithfull, KTRI, January 1998.
This note replaces note number PPA0006
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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