On the leafy nature of lodicules in the genus Triticum (Poaceae)

Abstract

Lodicules are important organs creating the mating system in grasses, in a range between autogamy in clestogamous flowers and allogamy in chasmogamous flowers. This balance is the main factor determining variation patterns in plant populations. Recognition of variation in lodicule morphology is especially important in wheat, the main crop of the world. For this reason, a broad range of species of wheat was evaluated by means of characters showing the leafy nature of lodicules. The characters were studied under polarizing and epifluorescence microscopes. Development of lodicule stomata is different than that in leaves. Development of stomata and xylem, is distinctly correlated. Other short cells created by epidermal meristemoids are developmentally rather independent of both stomata and xylem. Interrelations between stomata, xylem and morphogenetic traits of the abaxial epidermis of the lodicule are illustrated by pictures and diagrams of numerical analyses, including a non-metric multidimensional scaling method. Some unthreshable wheats, such as Triticum diccocum, T. ispahanicum and T. spelta, have more leafy lodicules, but intraspecific variation appears in the form of +leafy vs. −leafy lodicules. Formation of leafy lodicule morphs does not depend on the ploidy level of wheat. An intraspecific mosaic of + or −leafy lodicules proves a mutational origin of their leafy characters.