Elements de precision sur la systematique d’especes adventices dugenre corchorus l. (tiliaceae) au Senegal

Corchorus L is a genus includes nearly 40 species widelydistributed throughout the tropics and is represented in Senegal by 5 species according to Berhaut : C. aestuans L.; C. fascicularis Lam., C. olitorius L. with 2 varieties C. olitorius var olitorius L. and C. olitorius var incisifolius Asch. & Schw; C. tridens L. and C. trilocularis L.. Interest for these species is both economic and systematic. Indeed, beyond their weed statute and because of their ethnobotanical properties some species are cultivated. Besides, in the botanical point of view they belong to a genus which is a transition group between two tribes ; Tiliae and Grewiae. Even works done on the genus, identification of these species is still difficult. In fact, the more discriminant characters put ahead concern those of the fruit, an organ which appears late in the plant life cycle. Investigations on vegetative and reproductive organs on adult plant showed that, the presence or absence of basal hair on the limb, the dentate or lacerate leaves, the ovary 3 or 5-celled, the circular or hexagonal or pentagonal or trigonal secttion of the fruit, the seeds contiguous or separate inside the fruit are additional characters which could better help to identify these species.