Giant Bramble - New Invader In Knuckles Mountain

l by Dr. Lalith Gunasekera

(November 11, Melbourne, Sri Lanka Guardian) This is not Giant Mimosa (Yoda Nidikumba). Another alien invader found in Knuckles mountain range at Riverston area commonly known as Giant Bramble (Rubus alceifolius). People in Sri Lanka not familiar with this species but I straight away recognised the species as it has been a big problem in tropical parts of Australia and also listed by IUCN among the top 100 invasive species of the world. It is normally found on road shoulders and the edges of rainforests. 

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 growing through Knuckles

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.

Control:

Herbicide can be used by applying as an overall spray during the early flowering period, making sure that the leaves and stems are thoroughly wetted. Penetration of thick clumps may be difficult and re-spraying may be required.

I would like to urge relevant authorities to quickly identify the plant and make suitable measure to remove this species as soon as possible. The species is still in early stages of its invasion (as my observation within very short time period) in Knuckles region. Don’t let it loose to our endemic forest and patina grasslands of Knuckles. Otherwise Knuckles Protected Forest will be a paradise for “invasive plants”