Orobanche zajaciorum Piwow., 2015

Piwowarczyk, Renata, 2015, Orobanche zajaciorum (Orobanchaceae): a new species from the Caucasus, Phytotaxa 201 (3), pp. 214-220 : 215-218

Orobanche zajaciorum Piwow. , spec. nov. ( Figs. 1 , 2 )

Type: ― GEORGIA. Samtskhe-Javakheti: steep rocky slopes, S exposure, on the road between Tsaghveri and Kimotesubani, 10 km ESE of Borjomi, 1056 m, 2 June 2014, R. Piwowarczyk s.n. (holotype KTC!; isotype KRA!) .

Description: ―Small plant, (10–)15–17(–24) cm tall, pale pink, dirty pink, pale white-yellow. Stem simple, (1.5–)2.2– 3.2(–4.0) mm in diameter in the middle part, slightly widening towards the base, up to 4–7 mm; slightly bulbous at base; slightly striate (clearly striate when dry); densely glandular-pubescent in the upper part, with white or, rarely, pale yellow (orange when dry) short hairs 0.2–0.4 mm; stem pale or dirty pink, pale violet or rarely pale yellow (pale brown when dry). Basal leaves 10–13(–15) mm × 3.0– 4.5 mm, ovate-lanceolate (triangular) to lanceolate, imbricate, glabrous abaxially, but shortly ciliate at the edge with hairs ca 0.2 mm. Upper leaves 9–12 mm × 2.3–4.0 mm, narrowly lanceolate to lanceolate, becoming sparse above, more or less erect, pale yellow, changing early to brown, especially at the top; densely glandular-pubescent abaxially, with short hairs up to 0.3 mm. Inflorescence (2.8–)4.0– 8.5 cm × (1.8)2.0–3.0 cm, cylindrical to slightly ovate, shorter than the remaining stem; (5–)13(–26)-flowered, dense. Bracteoles are absent. The flowers are small, bent forward, and geniculate. Bracts 8–13 mm × 3.0– 4.5 mm, shorter or equal to the corolla, narrowly lanceolate, frequently deflexed, with white or pale yellow glandular hairs. Calyx (5–)7–8(–11) mm long, (1.6–)2.0(–2.5) mm wide at the widest point, shorter than the corolla tube, of up to half a corolla; segments simple, entire, narrowing to the apex; long acuminate teeth with a gently ovate base; segments free, clearly separate; dense glandular-hairy at base, hair forming sparse cover at the edge and the apex, hairs short ca 0.2 mm, white or pale yellow; lower parts of calyx pale yellow, pink, violet or purple with the tip, nerves conspicuous in dry specimens. Corolla (11–)13–15(–17) mm long, 3–4 mm in diameter in the central part; the dorsal line strongly curved, geniculate, only slightly inflated at base; externally glandular-pubescent with white or pale pink (in dry form, orange) glandular hairs of 0.1–0.3 mm, more or less abundant, hair cover slightly denser at upper lip; inside glabrous; corolla basally yellowish-white, upper parts pale pink with violet or dark pink veins; upper lip with two short, broad lobes, emarginated, patent or, rarely, erect, sloping down; lower lip with three oval lobes, central lobe slightly larger than lateral lobes, irregularly dentate on margins; entrance to interior corolla seen from below is characteristically flattened longitudinally. Stamen filaments obliquely inserted, adaxial filaments 5 mm above the corolla base, abaxial at 3.8–4.0 mm, slightly widened at base. Filaments 7–10 mm long, clearly geniculate, densely villous in the base to middle part; non-glandular and glandular hairs up to 0.3 mm long, upper part with rare short, white, glandular hairs; filaments white to pale yellow. Anthers 1.0– 1.1 mm long, ochre, paler when dry; glabrous with sparse short glandular hairs (ca 0.1 mm) located at the line of fusion. Ovary 6–8 mm × 2–3 mm, glabrous or with very sparse white glandular hairs ca 0.1 mm above; lateral opening by two longitudinal slots. Style 6–8 mm long, with very sparse glandular hairs or glabrous, dark pink. Stigma bilobed, with numerous warts (orange when dry) on the lobes and dark pink, violet to purple; stigma is hidden in the corolla and does not protrude. Seeds ovoid or oblongoid; seed coat reticulate with polygonal shallow cells, which range from more or less isodiametric or irregular to tangentially elongated; seed coat is pitted; a narrow trough is present on radial walls of seed wall cells. Pollen inaperturate, spheroidal.

Distribution and habitat: ―The species is probably endemic to the Lesser Caucasus. It was found at one locality and requires further research. The locality’s altitude is over 1000 m, between the Meskheti and Trialeti mountain ranges, at the foot of Mount Tortiza (1996 m). It grows by the roadside, between Tsaghveri and Kimotesubani, 10 km ESE of Borjomi, on steep, rocky slopes and landslides to the Gujaretistskal river valley (right tributary of the river Mtkvari). The upper parts of the slopes are covered with loose hornbeam oak forests, partly interspersed with scrub communities (with Carpinus orientalis as the dominant species) and xerothermic rocky mountain vegetation. The region where the species was recorded is mostly composed of Tertiary sediments (clay, marl, and sandstone) and Quaternary volcanic bedrock (andesite, basalt, and dolerite). Geologically, it belongs to the Lesser Caucasus mountain system (Meskheti- Trialeti Range) ( Akhakatsi et al. 2008, Nakhutsrishvili 2013).

Phenology: ―Flowering period May–June, fruiting at the end of June and July.

Ecology: ―Parasitic on Scutellaria sosnowskyi Takhtajan (1940: 24) ( Lamiaceae ). The flowers of O. zajaciorum emit a strong carnation scent.

Etymology: ―The epithet “ zajaciorum ” honours Maria Zając and Adam Zając, a married couple, Polish professors, prominent botanists from the Institute of Botany, Jagiellonian University in Cracow.

Conservation: ―The known locality of Orobanche zajaciorum lies outside protected areas, in the vicinity of the Borjomi-Kharaguli National Park and Nedzvi Sanctuary. The locality is threatened due to the close proximity of the main road and mechanical destruction threatening it through landslides of soil and rock material down the slope, so this newly-discovered species should be listed as endangered ( IUCN 2013).

Discussion: ―The newly-described species habitually is close relative to Orobanche section Orobanche Teryokhin subsection Galeatae (Beck) Teryokhin (1993: 39) . The corolla shape of O. zajaciorum is very similar to O. caryophyllacea Smith (1798: 169) and O. teucrii Holandre (1829: 322) , especially due to the helmet-shaped upper lip, and the relatively narrowly tubular flower like O. lutea Baumgarten (1816: 215) . However, the species of O. subsection Galeatae are much taller and have larger flowers (usually 18–30 mm), broad bidentate calyx segments, different hosts, or yellow colour of the stigma, like O. lutea and O. schelkovnikovii Tzvelev in Novopokrovskij & Tzvelev (1958: 686). O. zajaciorum , due to its small size, distinctively curved geniculate and small flowers (to 17 mm), simple and narrow calyx segments is difficult to confuse with other taxa of the Orobanche subsection Galeatae or other. I found no herbarium material (especially in LE or TBI) from other regions corresponding to this taxon. Also, the host, Scutellaria sosnowskyi , facilitates the identification of this taxon.

Heretofore, within the genus Scutellaria , only S. hirta Sibthorp & Smith (1809: 425) was given as a host of O. cypria Reuter in Unger & Kotschy (1865: 294) and was known from Cyprus ( Beck 1930); records in Iran and Iraq ( Beck 1930, Schiman-Czeika 1964) require confirmation ( Meikle 1985). However, O. cypria differs significantly from the newly-described species: mostly maroon or red stem and flowers, the calyx is divided into two teeth, the corolla is slightly curved with strongly plicate and fimbriate-denticulate margins of lobes.

Georgia occupies an interesting geobotanical position as a part of the Caucasus region which connects Europe and Asia. The complex orographic structure of Georgia and its geographical position account for the geographical and ecological isolation of some plant communities, which has resulted in a high degree of local endemism, as well as a variety of species of different geographical-genetic elements. The newly-described species can probably be found in the following localities within the range of the host Scutellaria sosnowskyi , covering eastern Turkey to the Transcaucasus ( Turkey, Armenia, Georgia), that is, mainly the Lesser Caucasus. Attention should also be paid to the known hybrids of the host plant S. sosnowskyi ( Cicek & Yaprak 2011) , or other species of this genus, and family Labiatae .

Figures

FIGURE 1. Orobanche zajaciorum. A. Plant. B. Flower, side view. C. Flower, front view. D. Segment of the calyx. E. Bract. F. Leaf. G. Open corolla and androecium. H. Anther. I. Gynoecium. J. Stigma. Illustration by Jolanta Urbanik.

FIGURE 2. Orobanche zajaciorum. A. Habitat. B, D. General habit. E, F. Inflorescence. C. Host plant Scutellaria sosnowskyi. Photos by Renata Piwowarczyk.