Patterns of style polymorphism in natural populations of Narcissus tazetta L

Stylar polymorphism is a sexual mechanism of the hermaphroditic plants that enforces out-crossing. It involves floral variants that differ in the position of their style length but with anthers at a similar height. These dimorphic species differ from the typical heterostylous species because they lack the reciprocity of sex organs and intra-morph incompatibility. Stigma height dimorphism occurs in some Narcissus species and is associated with a particular flower shape. In this study, we examined the sexual polymorphism of Narcissus tazetta L. We investigated the morph distribution in 22 natural populations from Algeria. To assess the morphological diversity of these populations, we used biometric analyses of various floral traits. We also investigated the breeding system of N. tazetta by analyzing the seed set and counting the pollen tubes and fertilized ovules, resulting from free, self, and cross-pollinations 24-h and 6-day post-pollination. The results showed a variable morph frequency, depending on the population. It deviates from the expected isoplethy (1:1 morph ratio) to a significantly dominant L-morph in most populations. In addition, the results showed that style morph is associated with variation in herkogamy and some floral traits. A continuous variation of style length was detected particularly in L-morph plants. Our results confirmed the late-acting self-incompatibility and the intra- and inter-morph compatibility of N. tazetta . These results may contribute to clarify the stylar polymorphism evolutionary pathways in Narcissus .