Ongzi, a zeal HORTICULTURIST,yet resides in a plant-free apartment…… thinks that plants deserved to be treated as LIVING THING, not merely as plants …… strongly condemns any form of CRUELTY TO PLANTS, yet enjoys feast on them…… collects only e-HERBARIUM, and proudly encourages others to do the same……
hysterophorus is a species of
flowering plant in the aster family, Asteraceae. Originated from the American tropics, it is
now spread all over the world. It
invades all disturbed land, including farms & plantation, pastures,
roadsides, park and gardens in India, Australia, Africa and Asia.
hysterophorus is an annual plant of
the Asteraceae family. It normally grows to 30-90 cm in height, but can grow up
to 1.5-2.5 m. It occurs in humid and
subhumid tropics, capable to grow on a wide variety of soil types
Flower heads are both terminal and axillary,
penduculate and slightly hairy; composed of many florets formed into small
white capitula, 3-5 mm in diameter. Each
head consists of 5 -8 fertile ray florets and about 40 male florets. First capitulum forms in the terminal leaf
axil, with subsequent capitula occurring progressively down to stem on lateral
branches arising from the axils of the lower leaves. Thousands of inflorescences may be produced
at the apex of the plant during the season.
Seeds are black, flattened, about 2 mm long. A plant can produce about 15,000-25,000 seeds. Seeds buried in soil can remain viable for at
least 4-6 years. Germination occurred at
10-25°C, over wide range of soil pH. Germination rate is extremely high.
Flowering may begin as early as 4 weeks after
germination. Life circle is about 86
days under optimum conditions, up to 335 days under unfavourable conditions.
Physiological studies have shown that P. hysterophorus has a low
photorespiratory activity and has the C3 photosynthetic pathway but with
positive C4 tendencies.
Its wide adaptability, photo- and
thermo-insensitivity, drought tolerance, strong competition, allelopathy, high
seed production, longevity of seeds in soil, small and light seeds that are
capable of long distance travel via wind, water, birds, vehicles, machinery,
contribute to its rapid introduction worldwide.
hysterophorus is a vigorous weed that
colonises pastures and farms. Its
presence reduce the pasture and crop production, as well as threatening the local
The presence of P.
hysterophorus pollen grains inhibits fruit set in tomato, brinjal, bean,
It found its way to India in the 1950s via
contaminated wheat imported from the USA.
Today, approximately 2million hectares of land in India have been
infested with P. hysterophorus.
hysterophorus was introduced to
Australia via the movement of military aircraft and machinery during WW2 and
pasture seeds. In Queensland, it is
declared a Class 2 plant under the Land Protection (Pest and Stock Route
Management) Act 2002.
hysterophorus is linked with several
health problems, both in human and domesticated animals.
Contact with P.
hysterophorus causes dermatitis and allergic respiratory problems in humans
and cattle, due to the presence of toxin parthenin.
Livestock fed on grass mixed with its leaves too will
develop deteriorated quality of milk and meat.
It also causes diarrhoea, severe popular erythematous
eruptions, breathlessness and choking.
hysterophorus is used in its native
neotropics as herbal remedy for various intestinal and skin disorders. It has potential medicinal properties for
skin inflammation, rheumatic pain, diarrhoea, urinary tract infections,
dysentery, malaria and neuralgia.
Compost produce from P. hysterophorus can lower weed population, possibly due to
allelophatic compounds present in it. The
allelophatic substances may be used as insecticide, herbicide, fungicide and
Removal of heavy metal and dye from the environment.
Chemical control with glyphosate has found to be
unsuccessful. Paraquat is effective only
when the plant is young. Manual removal
can only be done when the population is small.
Biological control by leaf-feeding beetle from Mexico,
Zygograma bicolorata is reported to
be able to defoliate and kill the plant.
Deadly bloom: The dangerous weed with flowers growing wildly in Sidam, Kulim.
SUNGAI PETANI: It has been dubbed
the “worst weed of the century”, destroying native flora and crops, causing
rashes that can leave humans permanently scarred and damaging the intestines of
animals that eat it.
hysterophorus, it was first detected here in September last year in
Ulu Yam, Selangor.
highly-allergenic plant has since been spotted in Perak, Kedah and Negri
Sembilan, raising fears that it has spread throughout the country.
accounts show that the plant has even resisted attempts to control it through
of flowering plant native to Mexico, it can cause severe skin disease and
hayfever in humans.
also toxic to livestock such as goats and cows, causing fevers, ulcers,
anorexia and intestinal damage, and can quickly replace native flora by
releasing toxic substances, causing massive crop loss.
in appearance toulam raja,P.
classified as a dangerous pest under the Plant Quarantine Regulations 1981 and
can quickly propagate.
to Professor Dr S. M. Rezaul Karim of Universiti Malaysia Kelantan, this is
because one plant, which can reach several feet in height, can produce hundreds
of thousands of seeds during its four-week life cycle.
seeds can be dormant in the ground for up to 10 years, making it impossible to
get rid of.”
Petani, some areas had been sprayed with herbicide, only to see fresh plants
springing anew just days later.
spreads like wildfire. You can look at examples in other countries, such as
Australia which spends millions of dollars yearly trying to control it,” said
Dr Karim, who heads the university’s parthenium weed research group.
to Dr Karim,P. hysterophorusnot only competes with other plants
for nutrients – it also releases chemicals which damage other plants.
effect on people, he said, was particularly worrying as it often grows by the
roadside where the public can easily come into contact with it.
to find out how many communities in Malaysia have been affected,” he said.
nations, the rash can become so bad it leaves people permanently scarred. It
can take three months for the symptoms to subside,” he said.
Starduring a recent
field trip to Sungai Petani saw the weed growing as high as 1.2m (4 ft) in
close proximity to restaurants, paddy fields, businesses and irrigation drains
that allow the seeds to hitch a ride to other areas, thus propagating its
to DOA representatives, the area had been sprayed several times with weedkiller
to no avail.
media release, the DOA listed several methods of controlling the weed,
including destroying the weed in its early stages before it flowers and
produces seeds, and curbing it in residential areas using salt water in a 1:4
ratio of salt to water.
department believes that the weed arrived in Malaysia by way of seeds being
carried through imported machinery or in fertiliser.
known affected areas are Kinta, Hulu Perak, Selama, Perak Tengah, Manjung,
Kuala Kangsar, Pokok Sena, Hulu Selangor, Kuala Muda, Kota Setar, Seremban and
Plant Biosecurity Division has formed a technical committee on the control,
containment and removal ofP. hysterophorusthat will come up with a standard
containment operating procedure and work with state governments to identify and
monitor problem areas as well as destroying existing weeds.
agricultural officers have been briefed on how to deal with the problem while
an exercise to identify places where the weed grows is already underway.