Plant Introduction, 85/86, 85–92 (2020) https://doi.org/10.46341/PI2020007 UDC 581.47:582.579.2(477-25) RESEARCH ARTICLE 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 V.V. Gritsenko M.M. Gryshko National Botanical Garden, National Academy of Sciences of Ukraine, Timiryazevska str. 1, 01014 Kyiv, Ukraine; [email protected] Received: 27.01.2020 | Accepted: 23.05.2020 | Published: 30.06.2020 Abstract The objective of this study was to analyze the 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, National Academy of Sciences 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. Fruit parameters were measured using a regular ruler. Morphological terms are provided, according to Artyushenko & Fedorov (1986). Colors were determined by Bondartsev’s (1954) scale. Results. In all analyzed species, the 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 the 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. The 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. The 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 the lower part indehiscent. The upper parts of the valves diverge, while the lower part of the capsule remains unopened. Conclusions. It was found that the shape of the 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, which should be analyzed precisely in future. Keywords: Iris, fruit, loculicidal capsule, diagnostic features, rare steppe plants, capsule dehiscence © The Authors. This content is provided under CC BY 4.0 license. V.V. Gritsenko Introduction within natural ranges, while I. halophila and I. graminea – outside. Representatives of the genus Iris L. In the previous studies, I examined the (Iridaceae Juss.) are ornamental herbaceous sozological characteristics, historical aspects plants characterized by significant species of the introduction, the number, and the diversity and grow in many botanical gardens condition of the populations of the introduced and arboretums in Ukraine (Mashkovska, species of the genus Iris (Gritsenko, 2005, 2015; Gritsenko, 2018). Iris halophila Pall., 2012, 2019b). In recent years, the success of I. pumila L., and I. hungarica Waldst. et Kit. the introduction of rare Iris species in the are rare steppe species protected at regional meadow-steppe cultural phytocenosis has level in different areas of Ukraine (Andrienko been evaluated, and preliminary analysis of & Peregrym, 2012). I. halophila belongs to the the fruit morphology was provided (Gritsenko, subgenus Xyridion (Tausch) Fourr., I. pumila 2017b, 2019a). and I. hungarica – to the subgenus Iris. Fruits Mature and dry Iris fruits are little visible of these species were partly investigated among the grasses and often overlooked. by Fomin & Bordzilovsky (1950). So far, Moreover, the identification of dry fruits of Dykes (1913) investigated principal ways of Iris species is challenging, especially taking fruit dehiscence in the genus Iris. Later into account incomplete descriptions for Rodionenko (1961) investigated the relation of the plants introduced in the conditions of the fruit dehiscence to the phylogeny of main meadow-steppe. There is a strong practical systematic groups in the genus. need to distinguish the fruits of Iris species The peculiarities of fruits and seeds in by morphological peculiarities for purposes some other Iris species were also sporadically of introduction. Hence, my objective was to investigated (Abramova & Kryukova, 2013; analyze the morphological structure of the Skrypec & Odintsova, 2015; Minjal & Boldyrev, fruits of I. halophila, I. pumila, and I. hungarica 2016; Biryukova et al., 2018). Minjal & Boldyrev and to reveal common and distinguishing (2017) also successfully applied the features of morphological features, which can be used seeds in the development of the identification for identification of these plants in meadow- keys of Iris species. steppe cultural phytocenoses. Shvets (2006) was engaged in the study of biological peculiarities and fruit morphology of 14 Iris species (including I. halophila, Material and methods I. pumila L., and I. hungarica) in connection with the introduction in the condition of The studies were conducted in 2015–2019 at the National Arboretum Sofiyivka located in the botanical-geographical plot “Steppes of Right-Bank part of the Forest-Steppe zone Ukraine” of the NBG. Fruiting was observed of Ukraine. The plants studied by Shvets in all four Iris species. I. halophila, I. pumila, were grown with the application of weeding and I. hungarica formed well-developed fruits and irrigation technologies. While in our that were included in the current investigation study, plants were grown in the composition (Fig. 1 A–C). However, I. graminea produced of meadow-steppe cultural phytocenosis, only undeveloped fruits, which stoped or which is characterized by considerable lingered in their growth and development, phytodiversity (Gritsenko, 2017a). In our case, and dried out prematurely. Therefore fruits of the conditions of Iris introduction were close I. graminea were excluded from the analysis. to the natural, and were characterized by To evaluate the morphological features strong competition with other plant species, of the fruits, 30 samples of each species without additional weeding and watering. were collected and investigated under ×2.0 In total, four rare steppe species of the optical lens. Fruit diameters were measured genus Iris (I. halophila, I. pumila, I. hungarica, in the middle part before dehiscence. All and I. graminea L.) are introduced on botanical- parameters were measured using a regular geographical plot “Steppes of Ukraine” of the ruler and, hence, rounded with a precision of M.M. Gryshko National Botanical Garden, 1 mm. Tables represent the arithmetic means National Academy of Sciences of Ukraine calculated following Lakin (1990). Deviations (NBG). I. pumila and I. hungarica exist here of the author’s original data from the data 86 Plant Introduction • 85/86 Morphology of Iris halophila, I. pumila, and I. hungarica fruits in the cultural phytocenosis A B C Figure 1. Unripe fruits of Iris halophila (A), I. pumila (B), and I. hungarica (C). Scale = 1 cm. published in the literature were calculated Capsules were dehiscing longitudinally by following formulae: Dev = 100 – y × 100 / x, along the carinal grooves (i.e., along the dorsal where x – author’s data, y – literature data. vein of each carpel) in the direction from top Morphological terms are given accordingly to bottom, and therefore are belonging to the to Artyushenko & Fedorov (1986). Colors loculicidal type. were determined and named following the Bondartsev’s (1954) scale, which the best reflects the natural colors of the fruits. Plant Morphological peculiarities of Iris halophila names are provided according to The Plant List capsules (2020). Species were determined according to Size: capsules are 3.5–4.8 cm long, 1.6–1.8 cm the Prokudin (1987). in diameter (Fig. 2 A–D). Shape: cylindrical All photos were captured by the author (Fig. 1 A; Fig. 2 A, B). After opening, they become using a Canon Power Shot SD 4000 IS Digital wineglass-shape (Fig. 2 C, D). The upper part of ELPH camera. the capsule: elongated into a long apical spout (0.6–1.0 cm), which is thin, slightly bent to the side (Fig. 2 A). Surface: smooth, with veins, Results matte (Fig. 2 A–D). As the capsule matures, a slight whitish plaque is observed. The capsule Common features of Iris halophila, I. pumila, has six sharp and well-expressed ribs located and I. hungarica capsules along both sides of dorsal grooves (Fig. 2 A–B). Genus Iris is characterized by a syncarpous Peduncle: 3.0–4.8 cm long, almost as long as capsule composed of three fused carpels the capsule. (Fig. 1). In the place of fused edges of carpels Dehiscence: complete (Fig. 2 C) or almost is formed a commissural (septal) suture. Along complete (Fig. 2 D). As the capsule matures and a midrib of each carpel, a carinal or dorsal opens, the upper parts of the valves diverge groove is formed. and bend, but near the base, the valves remain Investigated capsules are straight and connected (Fig. 2 D).