Gnidia species

Abstract

DISTRIBUTION: G. burchelli occurs more or less in the eastern half of the country and in the Western Cape, while G. polycephala is to be found in the drier parts of the Karoo and the Northern Cape province.

BOTANICAL DESCRIPTION: Gnidia burchellii: A woody, much-branched shrublet ± 1 m high. The branches have a reddish-brown bark. Just under the bark are some fine silvery silky threads, which are exposed when a twig is snapped and the bark pulled away from the wood. This helps to identify the plant. The leaves are carried mainly at the upper ends of the branch and distinct scars remain when they drop. The flowers are yellow, tubular and carried in dense clusters at the ends of the branches. The fruit is small, 1-chambered and contains a single seed. Gnidia polycephala: A perennial with a strong taproot. Much-branched from the base and forms a densely tufted bush ±50 cm high. The grey-green stems have few side branches and bear leaves only in the young stages. Small, dense heads of flowers subtended by broad papery bracts are borne at the ends of the branches. The flowers are tubular, yellow and hairy on the outside. The fruit is covered with plumes of long, silvery hairs, is 1-chambered and contains a single seed.

TOXIC PRINCIPLE: Esters of the diterpenoid phorbol, similar to daphnetoxin.

TOXICITY: • Relatively toxic. • Powdered plant irritating on skin and mucous membranes.

MECHANISM OF ACTION: • Severely irritant. • Affects rapidly dividing cells.

SYNDROMES: Gnidia intoxication.

SYSTEMS AFFECTED: Gastro-intestinal and respiratory systems.

CLINICAL SIGNS: Respiratory system: • Dyspnoea • Forced expiration with grunting (steun). • Peritracheal and subcutaneous emphysema of head (“lugdikkop”), as result of rupture of alveoli and air escapes into mediastinum and further. G.i.t.: • Anorexia • Ruminal atony • Diarrhoea.

NECROPSY: Macroscopical findings and histopathology: • Hyperaemia, congestion, oedema and emphysema of lungs • Lymphoid atrophy and karyorrhexis • Necrotic to pseudomembranous enteritis • Nephrosis • Myocarditis.