Weed Paradise: World Heritage Listed Central Highlands Of Sri Lanka --- Part 8 - Sri Lanka Guardian

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Wednesday, March 21, 2018

Weed Paradise: World Heritage Listed Central Highlands Of Sri Lanka --- Part 8

Giant bramble originated in Central America (Mexico) and introduced as a garden ornamental to lots of countries including Australia.




by Lalith Gunasekera

Giant bramble

( March 21, 2018, Victoria, Sri Lanka Guardian) Giant Bramble is native to China, Taiwan, Cambodia, Indonesia, Laos, and Thailand. It is a coarse, vigorous scrambling shrub with a woody rootstock, covering other plants and forming thickets that reproduce by seed and layering. Stems robust, thick primary canes up to 5 m long, covered with a felt of dense brown hairs and scattered hooked prickles. The stems erect at first and then arching and scrambling over other plants.

Short secondary canes producing flowers develop in the leaf axils of primary canes in the second year of the growth. Leaves are green above, velvety brown below due to a dense covering of reddish hairs. Leaves set alternatively on stems, 12.5 cm across, deeply notched at the base with 5-7 shallow but finely serrated lobes.

Flowers white, 1.5 to 2 cm diameter, in clusters at ends of secondary canes. Fruit a succulent aggregate berry of edible 1 seeded segments or drupelets, red when ripe. Seeds are small and black in colour. Seeds spread by birds and other animals and rooting of cane tips.

Giant bramble has a short woody rootstock giving rise to a sparsely branched main root with a number of fibrous laterals in the upper soil layers. It occurs in wet gullies, creek banks and around rainforests in the humid tropics.
Impacts:

Giant bramble forms dense thickets due to its high growth rate that smother other plant species. Barbed canes restrict access to water and readily invade developing pasture lands, newly clear lands and forests. It will encroach onto roadways, hindering access to useful areas and spread into disturbed rainforest areas.

Tree Daisy

Tree daisy (MONTANOA HIBISCIFOLIA) is not commonly found in Sri Lanka. This is new invader found in our Central Highlands. I have noticed this plant at roadside from watawala junction to Maskeliya.

This plant originated in Central America (Mexico) and introduced as a garden ornamental to lots of countries including Australia.

A soft wooded, many branched perennial shrub which grows up to 3 m or more. The leaves are opposite, simple, deeply palmately lobed into 5-7 pointed lobes with toothed margins. The colour is dark green above and greyish underside, velvety hairy on both surfaces. Leaf stalk is about 3-20 cm long and winged along the upper side.

Tree daisy flowers have white petals and yellow centres, borne in large showy axillary or terminal sprays and perfumed. The flower is about 5 cm wide. The fruits are brownish dry papery balls, about 25 mm across, bearing numerous individual one seeded fruit about 10 mm long. Seeds spread by water, animals, birds and humans. The plant can invade rainforests, creek banks, undamaged lands and roadsides. Look out of this plant in Central Highlands.

Blue Stars

Nil Mal (ARISTEA ECKLONII) was introduced to Sri Lanka during the colonial period especially into Nuwara Elia and surrounding areas. Blue star is a small lily like plant native to the Southern and Western parts of Africa that was grown as a garden ornamental for its attractive blue star like flowers.

Blue stars is a long lived clumping plant that usually grows up to 70 cm tall. It develops clusters of long and narrow leaves (10-60 cm long and 5-12 mm wide) at the base of the plant and produces woody rhizomes in the ground. The leaves are straight or slightly curved, with parallel veins running lengthwise and leaves end with pointed tips. Plants produce upright flowering stems which are branched in their upper parts. These stems are flattened in cross-section and slightly winged.
Each flower last for only one day and only for a few hours in bright conditions. Flower is about 20-25 mm wide and has six bright blue petals. The fruit is an oblong capsule that is 12-20 mm long and slightly three sided. These capsules turn from green to brown as they mature and split open to reveal three compartments. Each compartment containing large number of small seeds about 1.5 mm long.

Seeds are dispersed mainly by water, wind. Thus blue stars spread primarily from seeds but it can also be propagated by dividing rhizomes, tubers, corns or bulbs.

It is an invasive species in high mountain forests in Sri Lanka near Nuwara Eliya and Horton Plains. Blue stars is listed as a weed in New Zealand and Australia where it grows in extensive patches within native vegetation, along roadsides, tracks, streamside and in open forest.

Baloon cotton bush

Balloon cotton bush (GOMPHOCARPUS PHYSOCARPUS) is origin of South Africa. The plant is found in India, Hong Kong, Hawaii, New Caledonia, the Caribbean, Mauritius and Sri Lanka. This species has been spreading in knuckles ranges and Nuwara Eliya district of central highlands.

A small upright and occasionally branched shrub usually growing 1-2 m tall but occasionally reaching up to 2.5 m in height. Younger stems and branches are covered with short soft hairs. A poisonous milky white sap exudes from damaged stems and leaves. The leaves are long (3.5-12 cm) and narrow (5-16 mm) with pointed tips and gradually narrowed at the base and arranged oppositely on the stem. Leaves are borne on stalks and have entire margins. The upper surfaces are green and hairless, while their undersides are often paler green and finely hairy, particularly along the central vein.

Individual flowers have five white petals and a crown like structure. At the centre which may be white or pinkish in colour. They are borne in small drooping clusters of 4-10 flowers near the tips of the branches, with the individual flower stalks all radiating from the same point.

The distinctive inflated fruits are balloon like in appearance and covered with soft spines. They are abruptly pointed, with a very short beak that is usually sunken into the indented tip of the fruit. These fruit contain numerous small black seeds (4.5 mm long and 2 mm wide) that are topped with a tuft of silky white hairs about 3 cm long.
Balloon cotton bush reproduces mainly by seed. These seeds are most commonly spread by wind and water. They also may be dispersed as a contaminant of agricultural produce or in mud attached to animals, machinery and other vehicles.

To be continued



( Dr. Lalith Gunasekera is an invasive Plants Specialist based in Mackay - Queensland )

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