Cotoneaster sp. (C.franchetii – orange and C. pannosus –
silverleaf cotoneaster) For this edition we refresh our memories about two familiar garden subjects classified as category 3 invaders.
Cotoneastersp has its origins in the northern hemisphere. The two species that have become invasive in our country are both of Chinese origin.
Our subjects areCotoneaster franchetii (commonly known as orange cotoneaster Afr.: Dwergmispel) native to south-western China and northern Thailand and C. pannosus (silver-leaf cotoneaster, Afr.: silwerdwergmispel) also native to China. Cotoneasters belong to the Rosacea family and are a familiar sight in almost every garden in our area, thriving in our cooler and milder climate. The small white flowers are insignificant, but those arching sprays of brilliantly hued berries are quite stunning. C. pannosus has become a troublesome noxious weed in Hawaii. Those pretty fruits, ingested in quantity are poisonous and parents and grandparents are advised to bear this in mind where there are young children playing in the garden. Birds however can eat many things we can’t and the berries are just as popular with our feathered friends, contributing to the spread of Cotoneaster plants outside our gardens. An interesting snippet I came across was that during the eighties, the species’ potential for natural hybridization led to confusion among growers as to the true identities of some species, and C.X cornubius is listed as of “Garden” origin. Add to that the ease of seed germination and propagation from cuttings and layering and the recipe for invasion is to hand.
Identification: The plants grow into substantial shrubs with long gracefully arching branches without thorns. Generally the young branchlets and undersides of the leaves are densely “felty”. In time the grey-green foliage of Cotoneaster franchetii (orange cotoneaster) becomes glabrous (without hairs) and shiny above, while the berries are orange-red in colour. C pannosus (silver-leaf cotoneaster) has dull-green foliage and its fruits are a dull deep red colour.
Invasive Status: The ease of propagation from seed and late summer cuttings contribute to the Cotoneaster’s invasive status. To all intents and purpose they also appear to be disease and pest resistant. They are quick growers and invade forest margins, kloofs and riverbanks and also grassland. We have identified and removed adult specimens along Hillside road and seedlings in our own backyard. Cotoneaster species are potential transformers and its classification as declared Category 3 invaders permits no trade or new plantings.