Iris setosa Pall. ex Link (1820: 71)

Boltenkov, Eugeny V., Menshakova, Marija Y., Gainanova, Ramziya I. & Rumjantseva, Zinaida Y., 2020, The first record of Iris setosa (Iridaceae) in Europe, Phytotaxa 437 (1), pp. 32-38 : 33-34

Iris setosa Pall. ex Link (1820: 71)

≡ Xyridion setosum (Pall. ex Link) Klatt (1872: 500) ≡ Limniris setosa (Pall. ex Link) Rodionenko (2007: 552) .

Protologue:—“[...] aus Sibirien”. Type (lectotype, designated by Hultén 1927: 256, as “type”):—[ RUSSIAN FEDERATION]. Ir. setosa , s.loc., [fl.], s.d., [ Pallas ] s.n. (B-W00993010 [digital image available at https://herbarium.bgbm.org/object/BW00993010], isolectotype HAL0071854 [digital image available at https://herbarium.univie.ac.at/database/detail.php?ID=540600]).

Notes on type specimens of Iris setosa :—The species was first described from Siberia by Link (1820) based on the specimens held at Willdenow Herbarium in Berlin. Currently, the original material of I. setosa at B is represented by a single specimen (B-W00993010) that was indicated as “ type ” by Hultén (1927), which hence represents a lectotypification of the name. This specimen belongs to the Pallas’ Siberian plants collection, which was given to Willdenow ( Stafleu & Cowan 1983, Sytin 2014). It is stored in a folder accompanied by a label on which Willdenow handwrote the name “ Iris setosa ”, a description copied from the protologue, and the provenance “ Habitat in Sibiria ”. This herbarium sheet bears the notes “ Ir. setosa . 1” in the upper right corner and “ Pallas W [illdenow]” in the lower right corner, which indicate the source of the material, i.e. the person from whom Willdenow allegedly received it ( Hiepko 1987). This apparently explains the reason for which the name I. setosa was ascribed to Pallas by Link. These handwritings were annotated by Leonhard von Schlechtendal, the Curator of the Willdenow Herbarium since 1822 ( Schlechtendal 1832, Stafleu 1972). Another specimen ( HAL 0071854) can be considered as original material for the name I. setosa . This specimen is evidently a duplicate, which came to Halle ( Germany) from the Willdenow Herbarium, probably through the purchasing of the herbarium of Schlechtendal (see also Boltenkov 2018), who was the director of the Botanical Garden at Halle between 1833 and 1866.

General description:—Perennial herb, up to 80 cm tall. Rhizome stout, branched, spreading centrifugally with time to create dense and subsequently cyclical colonies (clumps). Basal leaves ensiform, prominently ribbed but without evident midrib, 20–60 cm long and 0.8–2.5 cm wide. Stems usually 30–60 cm tall, exceeding basal leaves, with 1–3-flowered terminal branch and 1–2 lateral 1–2-flowered branches, bearing cauline leaves subtending each bifurcation. Bracts ovate-lanceolate, having short, acuminate apex, 4–6 cm long. Pedicels equaling bracts, 1.3–5.5 cm long. Flowers pale blue to violet, with reddish veins; colour variations can occasionally be found within a single population. Perianth tube ca. 1.3 cm long; outer perianth segments orbicular; inner segments usually reduced to bristles 0.7–2.6 cm long, variable in shape, with apex acuminate. Fruit roundly trigonal, thin-walled, much inflated, with apex not beaked. Seeds obliquely ovoid, with distinct raphe along one edge, light or dark brown, glossy; seeds ripen soon and rattle in the capsules. The flowering time is from June to August (depending on geographical origin); the fruiting time is from July to September. The plant exhibits the capability of within-flower self-pollination, or autogamy ( Burova 1970), but is often sterile under dry conditions ( Hultén 1927).

Voucher specimen:— RUSSIAN FEDERATION. [Murmansk Oblast], southeastern part of Kildin Island ( Barents Sea ), in sedge/cotton-grass marsh habitats, on the edge of a terrace, 69.332825°N, 34.30916°E, [fl.], 22 July 2018, R. I. Gainanova s.n. [originally in Russian] ( MASU Herbarium; Fig. 2 ) .

Notes:—Here we report the first record of I. setosa from Kildin Island, Murmansk Oblast, Russian Federation ( Fig. 1 , 3A ). The examination of herbaria in Eastern and Northern Europe and the study of all published Arctic floras of the European part of Russian Federation, including Murmansk Oblast, and neighboring European countries (e.g., Poyarkova 1954, Tolmachyov 1963, Kobeleva 1976, Tzvelev 1979, Webb & Chater 1980, Väre 2017) showed that, to date, I. setosa has never been reported so far from its native geographical range in Northeast Asia and North America. Therefore, the current study clearly indicates I. setosa as a species new to the flora of Europe.

The population of I. setosa found by us was constituted by 257 estimated reproductive individuals in full flowering or early fruiting stages, as well as 253 estimated vegetative individuals bearing one to seven rosette shoots. All reproductive individuals were growing in clumps of 50–200 cm in diameter, with each clump characterized by 1 to 162 flowering stems 27–60 cm long and 1 to 97 rosette shoots, most common by one-branched stems with 2–3 flowers, as well as by 2 or 3 stems with 1 or 4 flowers, respectively. From the Eurasian Iris species, I. setosa is easily distinguished in the flowering stage by the reduced inner perianth segments. In the field study of the Kildin Island population, the reproductive individuals clearly showed this feature ( Fig. 3B ).

The occurrence of I. setosa in Kildin Island is intriguing, since this population is greatly disjunct from the rest of the species range, and the way and time of its arrival on the island remain unknown. An explanation for the occurrence of this species on the island could be the possible naturalization of plants escaped from cultivation. However, according to interviews with local residents and our colleagues, who had studied Lake Mogilnoe for many years, no trace of horticultural activities has ever been recorded on the island. Indeed, we did not find any other adventive or cultivated plant on the island. Currently, Kildin is an abandoned territory with very few human activities conducted mostly around Lake Mogilnoe ( Strelkov et al. 2014, Krasnova et al. 2019). Previously, I. setosa was introduced in the Polar-Alpine Botanical Garden-Institute ( Zhukova 1967, Andreev & Zueva 1990), and authors of the present study have cultivated this species at MASU for more than a decade, and it did not show any tendency to naturalize in Murmansk Oblast. Furthermore, we have not found I. setosa on the populated places along the coasts adjacent to the island, including Teriberka Village, from which boats depart to Kildin Istand. Therefore, we may hypothesize that I. setosa is native to Kildin Istand, and probably arrived here through seed dispersal. The probability of long-distance dispersal through birds is very low, since birds have very rapid digestion and food passes through their bodies at a high rate ( Gill 2006). Moreover, seeds do not bear any appendages and do not show surface’s features that can allow them traveling stuck to the birds’ bodies. Therefore, this disjunction may provide evidence for past terrestrial connections. In fact, seeds of I. setosa can float on the water surface for long time ( Rodionenko 2013). In this regard, we suggest that the Transpolar Drift Stream (see Faleyev 1980, Rjabchikov 1988) could be one of the vectors for seed dispersal from Northeast Asia.

Figures

FIGURE 1. Maps of the Kola Peninsula (left), with a detail on Kildin Island (right) showing the locality (●) of collection of Iris setosa specimens.

FIGURE 2. Herbarium specimen of Iris setosa collected in Kildin Island, Murmansk Oblast, Russian Federation.

FIGURE 3. Iris setosa. A) General view of the population in Kildin Island; B) Flower with the small inner perianth segments (arrows).