Morphological peculiarities of fruits of the rare species Iris halophila Pall, I. pumila L. and I. hungarica Waldst. et Kit. (Iridaceae Juss.) in the conditions of introduction in the meadow-steppe cultural phytocenosis

Abstract

Objective – to analyze morphological structure and to reveal common and distinguishing features of the fruit in rare steppe species Iris halophila, I. pumila and I. hungarica introduced in conditions of meadow-steppe cultural phytocenosis in the M.M. Gryshko National Botanical Garden NAS of Ukraine (NBG).
 Material and methods. Fruits of I. halophila, I. pumila and I. hungarica were collected on the botanical-geographical plot “Steppes of Ukraine” of NBG during 2015–2019. Morphological terms are provided according to Artyushenko & Fedorov (1986).
 Results. In all analyzed species, fruit is a trimeric and trilocular loculicidal capsule with multi-seeded locules. This capsule is erect, straight, leathery, glabrous, opening by dehiscence from top to bottom along the dorsal veins of carpels. The morphological peculiarities of the fruits, which may be additional diagnostic characters of these species, are established. In particular, in I. halophila capsule is cylindrical with the upper part elongated into the apical spout (long, thin, bent to the side). The surface of I. halophila capsule is smooth, matte, six-ribbed. Ribs are located on both sides along each of dorsal veins (i.e., along the dehiscence stria). The dehiscence is complete with diverging upper parts of the valves that remain connected just at the base. Capsule of I. pumila is ellipsoidal with the upper part also elongated into the apical spout (short, thick, awl-shaped). The surface of I. pumila capsule is wrinkled, without ribs. Commissural (septal) suture and dorsal veins are protruding. The capsule dehisces completely by three slits, but the valves remain connected in the apical part and at the base. Capsule of I. hungarica is oblong-ellipsoidal, without apical spout. The surface is veined, grumous, with six grooves above the commissural sutures and dorsal veins, without ribs. The capsule of I. hungarica opens only partly toward the peduncle, leaving lower part indehiscent. The upper parts of the valves diverge, while the lower part of capsule remains unopened.
 Conclusions. It was established that shape of capsule, in particular structure of its upper part, presence of ribs and apical spout, as well as the surface features together with peculiarities of dehiscence are constant parameters and can be used as diagnostic characters to distinguish these species. The size and color of the capsules, as well as the number of seeds per capsule of I. halophila, I. pumila and I. hungarica varied – this may depend on environmental conditions, in particular geographical location, and many other factors, which should be analyzed precisely in future.