Weeds in our Area (Part Sixty Four)
By Bob and Ena McIntyre, Botanical Society of S.A. – Garden Route Branch
Continuing along the Acacia trail Part 64 examines Acacia Cyclops (Rooikrans, Red Eye). The earliest record of Rooikrans was in 1858 when it was catalogued by McGibbon amongst a number of exotics growing in the Cape Town Botanic Garden (NOT Kirstenbosch which was only established in 1913) at that time. It may well be that Baron von Ludwig had it growing in his Cape garden in 1835. Around the 1880’s Rooikrans together with Port Jackson and some indigenous seed were used for stabilising drift sand along the new road across the Cape Flats from Cape Town to Bellville and beyond. It was next mentioned in 1884 in the report of the Superintendent of Plantations of the Cape. He reported that 27 bushels (approx 972l - i.e. just short of 1m³) of seed had been collected, no doubt also for the purpose of stabilising drift sand. Until the mid 1900’s seed was freely distributed in the winter rainfall area from Port Nolloth to Port Elizabeth.
A. Cyclops is now well established in Mountain and Lowland Fynbos vegetation groups as well as the Southern and Eastern Cape Forest and Succulent Karoo areas. Seeds are dispersed by humans as well as other mammals such as the striped field mouse and baboons as well as birds such as francolin, guinea fowl, moorhen, doves, and starlings.
Identification: Rooikrans is a small rounded shrub or small tree without thorns 1.5-6m high. In windy coastal areas it tends to be wind-clipped and therefore lower. The leaves are phyllodes (leaf-like petiole with no blade), bright green and almost straight. Flowers are sunshine-yellow globular flower-heads that are evident throughout the year peaking between October and February. The seed pods are as broad as the leaves and when ripe are twisted and persist after the seeds are shed. The pitch black seeds are encircled by a double row of bright red or orange fleshy stalks, resembling a red eye hence the common English name.
During February 2000 a Small Fluted Galler midge (Dasineura dielsi) was introduced. Until then the persistent dry seed pod was a popular means of identification – today the dried out galls which have inhibited the production of fruit are the easiest means of identification.
Control: Acacia Cyclops does not usually coppice when felled so there is no need to use herbicide on the cut stump. Young plants can easily be hand weeded. The introduction of the Galler Midge has had a major impact on the species’ ability to produce seed and evidence of the presence of the Galler Midge has been found to the furthest reaches of the areas invaded by A. Cyclops.
Substitutes: Our indigenous smaller trees and large variety of shrubs are undoubtedly more attractive and appropriate options. For sand stabilisation our local ground covers, grasses and sedges are obvious choices. Trees/shrubs: Dais cotinifolia (Pompom Tree), Diospyros dichrophylla (Star apple) Canthium inerme (Turkey berry). Groundcovers: Plectranthus saccatus (stoep jacaranda) Plectranthus strigosus, Plectranrhus thunbergii and any of the low growing Pelargonium species.
Photo: With kind permission of John Hoffmann, Zoology Department, University of Cape Town
BotSoc Forthcoming Events
Plettenberg Bay: Saturday, 17 June - Hack at Lookout Park. Bitou municipality are on course to declare this a Nature Reserve. To participate please contact Jean or Maaike below.
BotSoc Contacts in your area: George/Wilderness: McIntyre’s 044 877 1360
Knysna: Chris Gow 044 387 1978, Ariane Rohloff 044 382 7993
Mossel Bay: Lucretia van der Walt 044 691 3230. Stilbaai: Janet Naude 028 754 1106
Plettenberg Bay (Bitou Twig): Jean Sparg 044 533 2625, Maaike Murphy 044 531 6857