EARLY LEAF ONTOGENY AND THE SHOOT APEX OF COLOPHOSPERMUM MOPANE (LEGUMINOSAE)

Shoot tips of Colophospermum mopane (Kirk ex Benth.) Kirk ex Léonard produce leaves which at maturity are bifoliate and devoid of stipules. Investigation of their early ontogeny, however, shows that these leaves begin as trifoliate structures partially enclosed by their stipules. The latter are fused along their mid regions, forming a tongue-like “connector.” The lower chamber of this stipule pair harbors the apical meristem while the upper compartment enfolds the two lateral leaflets. The terminal leaflet, histologically resembling the stipules, also fulfills a similar function by covering the top portion of its sister leaflets. Anatomically, the shoot apex displays a pendulum symmetry, with rather steep elevation of that internode portion which subtends the newly formed primordium. Some comparisons with the shoot apex of Hymenaea are drawn.