ИСТИНА

We present a comparative study of flower development in the early-divergent monocot order Alismatales. This order is remarkable for possessing probably the widest range of variation in floral ground-plan among monocots. Some species of several genera develop trimerous-pentacyclic flowers that are typical for monocots. However, in general, taxa in which the perianth is differentiated into sepals and petals demonstrate a tendency for an increased number of stamens and carpels, while retaining a trimerous perianth. In contrast, families in which the perianth consists entirely of tepals are more likely to show reduction in both merosity and number of floral whorls. Apart from ground-plan, floral development is dependent on inflorescence type and the presence and location of non-floral organs surrounding the flower. Flower-subtending bracts and floral prophylls create morphogenetic gradients resulting in unidirectional or spiral organ inception in whorled flowers.