Oenanthe incrassans: An enigmatic species from Turkey and its comparison with Oenanthe pimpinelloides (Apiaceae)

Abstract Oenanthe incrassans (Apiaceae) was discovered in Istanbul, Turkey. It is related to Oenanthe pimpinelloides, but it clearly differs in terms of leaves, inflorescence (ray, bracts, and bracteoles) and fruit features. A taxonomic description, some photographs of the species, geographical distribution and habitat features are given. Additionally, fruit micromorphology, stem, ray and fruit anatomy, and pollen features are studied for the first time and compared to Oenanthe pimpinelloides.


Introduction
Oenanthe incrassans Bory & Chaubert (Bory 1832) is one of the synonyms of the Oe. pimpinelloides L. (Linneaus 1753) in Flora of Turkey (Hedge and Lammond 1972). Foley and Southam published a study on Oe. incrassans and they recognized it as a distinctive plant of the Aegean region (Foley 2007). Th e species is an element of the East Mediterrenean area because of its distribution in Aegean region, but it hasn't been collected from Turkey until recently.
Foley and Southam also discussed Oenanthe thracica Griseb. which is the other synonym of Oe. pimpinelloides (Hedge & Lammond, 1972). Th ey said that Oe. thracica is conspecifi c with Oe. pimpinelloides and its taxonomy is in need of further study. Th eir result was based on examination of a specimen of Oe. thracica recorded as "Turkey (European)-A1(E) Edirne: Kesan, 6 July 1982, Nydegger 17003". In 2013 reported Oe. incrassans as a new record for Flora of Turkey based on this record (Özhatay 2013), and then it was added in the list of Flora of Turkey as a "doubtful species" (Menemen 2012). I have also examined specimen of Nydegger (deposite in E) which Foley and Southam determined as Oe. thracica, and in my opinion it is definetely Oe. pimpinelloides. Th is is consistent with an earlier determination of the sheet by Huber-Morath. Menemen (2012) thus recognized nine species (including doubtful species) in Turkey.
Within the scope of revisionary studies on the Oenanthe species in Turkey, numerous fi eld trips were held between 2014-2015, on one of which Oe. incrassans was discovered in Istanbul. Additionally, W and WU herbarium in Vienna, Austria were visited to investigate specimens of Oenanthe. During the investigation, undetermined specimens which were collected by Ernst Vitek from Istanbul were identifi ed as Oe. incrassans.
Th is study aims to present a full description of the species and resolve the delimitation between Oenanthe incrassans and Oe. pimpinelloides by comparing morphological, anatomical, palynogical and micromorphological analyzes and their ecological features.

Methods
Th e specimens of Oenanthe incrassans and Oe. pimpinelloides were collected in diff erent regions of Turkey between 2014-2015 and checked with relevant literature (Hedge and Lammond 1972, Cook 1981, Duman 2000. Herbarium specimens were deposited at GAZI. Th e specimens were compared with the types and other representative collections present at E, W, WU, GAZI (abbreviations following Th iers 2016). For the anatomic analysis, stem, ray, and fruit parts of the collected specimens were kept in 70% alcohol. Hand-made cross sections were fi rstly stained in sartur reagent (Çelebioğlu 1949). Detailed anatomic structures of the cross sections were photographed with a stereo microscope attached with a camera (Olympus E330). Relevant resources were made use of during the anatomic evaluation (Mauseth 1988, Dickison 2000. Pollen acquired from anthers of the herbarium specimens were prepared based on Wodehouse method, stained with basic fuchsin, and analyzed under light microscope (Wodehouse 1935). Th e pollen samples were placed on aluminium tape, coated with gold by using Polaron SC 502 Sputter Coater device, and microphotographed by Jeol JSM 6490LV model scanning electron microscope (SEM). SEM analysis of mericarp micromorphology was conducted with the same method. Th e terminology of the pollen and mericarp is based on Moore et al. 1991, Punt et al. (2007, and Doğan Güner et al. (2011).    Perennial, 50-70 cm tall, herb, glabrous, with ovoid or oblong tubers far from stem base. Stem erect, sparsely branched above, hollow, deeply striate (furrowed). Basal and lower stem leaves 2-pinnate, ovate to lanceolate in outline, up to 15 cm with petiole; ultimate segments with pinnatifi d lobes, ovate, 9-15 × 8-14 mm; petiole shorter than leaf lamina, broader at leaf base. Upper stem leaves 2-pinnate, ovate-triangular in outline; ultimate segments 2-2.5 cm long and 2-5 mm broad, elliptic. Umbels with 7-12 rays of subequal length (1.5-2 cm), rays becoming hardly thickened and elongating in fruit; involucral bracts 0-1, linear, up to 6×1 mm. Umbellets almost fl at, with unequal, thickened pedicels in fruit, many fl owered, about 1.5 cm diam., pedicel of surrounding fl owers longer than inner ones. Bracteoles 10-12, linear, ca. 3 × 1 mm. Petals radiating, creamy white, the outer fl owers are female, petals cordate, deeply emerginate in tip, inner petal surface papillate. Styles shorter than fruit, fruit oblong, 3.5-4 × 2-2.5 mm.

Oenanthe incrassans
Distribution, habitat and ecology. Oenanthe incrassans is distributed in Greece and Turkey (Figs 2-3). Th e species is distributed around Istanbul (Arnavutköy, Durusu-Terkos region), Turkey. Th e fl owering time is April, fruiting time is June. It grows on lake sides at 20-50 m altitude.
Morphology. Oenanthe incrassans is close to Oe. pimpinelloides, but it clearly differs in leaves, infl orescens and features of fruit. Th eir diff erences are given in Table 1.
Ray anatomy. Rays are hardly thickened and the shape of cross section is 8-10ridged and circular in outline in Oenanthe incrassans; but they are slightly thickened Shorter than fruit ± Equal fruit body Fruit 3.5-4 × 2-2.5 mm 2.5-3 × 1-1.5 mm and 7-ridged ovoid or oblong in outline in Oe. pimpinelloides. Th ere are 8-9-seriate collenchyma cells in Oe. incrassans; but 5-6 seriate in Oe. pimpinelloides. Pith cells are 3-4-seriate and disappear towards the center in Oe. incrassans; but they are present at the center in Oe. pimpinelloides ( Fig. 5a-b). Fruit anatomy. Size and shapes of mericarps show morphological diff erences between the two species. Th e cross section shape of mericarps is semi-circular in outline and 4-ridged at the dorsal surface in Oenanthe incrassans. However, it is triangular in outline and only faintly 4-ridged in Oe. pimpinelloides. Mesocarp tissue consists of two types of cells; parenchymatic-slightly thickened cells and lignifi ed sclerenchyma cells around vascular bundles. Th ere are 9-10-seriate parenchymatic cells in Oe. incrassans, but there are 4-5-seriate parenchymatic cells in Oe. pimpinelloides ( Fig. 6a-b).

Discussion
Th ere are many studies about anatomical features of genera of Apiaceae (Liu 2003, Ashena 2014, Akalin Urusak 2013, Yilmaz 2013, Lyskov 2015 because the fruit morphology and anatomy are distinctive characters which frequently clarify the similarities and diff erences between species. Also a lot of research shows that pollen features of the members of Apiaceae help to distinguish at species (Hebda 1985, Doğan Güner 2011, Yılmaz 2013. Oenanthe pimpinelloides shows wide distribution in the World and also in Turkey. Th e species has been recorded Aegean, Mediterrenean, Th race and Black Sea region in Turkey but not the East Anatolian region (Figure 2). Investigation of the collected specimens show that the plant has variable leaf characters. Oe. pimpinelloides not only prefers wetlands or marshy areas, but is also found on dry slopes or under the shade of trees. It has longer stems and leaves in wetlands than in dry habitats, but its infl orescence and fruit features remain unchanged throughout its range. On the other hand, Oe. incrassans only occurs in wet areas and it shows similar morphology all localities. Foley and Southam mentioned that morphological characteristics of Oe. incrassans were retained even in cultivation in England (Foley and Southam 2007). Oe. incrassans is placed in synonymy of Oe. pimpinelloides in Hedge and Lammond (1972) because these authors thought some characters such as the thick peduncle and rays of Oe. incrassans only refl ected local variation of Oe. pimpinelloides. After collecting Oe. incrassans and a lot of specimens of Oe. pimpinelloides from diff erent localities, and observing the diff erences outlined above (Table 1), we agree with treatment of Foley and Southam 2007 and recognize them as distinct species. Th erefore, there are nine species Oenanthe species in Turkey.