Anatomie du point noir de l'Artichaut (Cynara scolymus L.)

Abstract The « black spot disease » or localized necrosis of the receptacle is prejudicial to the french production of artichokes cv 'Camus de Bretagne1: hard, necrotical black granules develop inside the floral receptacle. A SEM structural study shows that the black spots are cellular nodal structures sclerified, inserted into the parenchyma of the receptacle; they are associated to the xylem bundles which they can contain. Resulting probably from an active autolysis, some caverns groove the noduls, sometimes breaking sieve elements. The black spot, non resulting from bacterial, fungal or viral attacks, is thus reminiscent of the typical structures of a restoration or a cicatrization after a physiological accident entailing the isolation and the desertion of an histological area injured by a lethal disorder, in fact a sieve conduction accident, probably bound to a gaseous embolism after « cavitation ».