FLORAL ORGANOGENESIS OF CALDESIA PARNASSIFOLIA (BASSI EX L.) PARL. (ALISMATACEAE)
泽苔草的花器官发生

The floral organogenesis of Caldesia parnassifolia (Bassi ex L.) Parl. was observed under scanning electron microscope (SEM). The primordia of the floral appendage initiated in trimerous pattern and acropetal succession. Three sepal primordia first initiated on radii spirally, and a whorl of three alternisepalous petal primordia formed nearly simultaneously after the inception of sepal primordia. The petal and stamen primordia initiated separately, and no petal-stamen complex was observed. The three anti-sepalous outer stamens arised after the initiation of petals, the other three inner (anti-petalous) stamens arised subsequently, and the six stamens were arranged in one whorl at subsequent stages of development, but still anti-sepalous and anti-petalous separately. The first whorl of 3 pistil (carpel) primordia originated opposite the sepal primordia, while subsequent pistil primordia formed rapidly in alternation with the preceeding ones, each whorl with 1~3 pistils. The significance of the spiral, acropetal development of corolla is discussed.