Orobanche cuprea Boiss. & Balansa, 1879

Uhlich, Holger & Rätzel, Stefan, 2015, A contribution to the taxonomy and phytogeography of Orobanche alba Steph. ex Willd. (Orobanchaceae), Phytotaxa 222 (1), pp. 1-16 : 2-4

Orobanche cuprea Boiss. & Balansa :

Some years ago, the first author saw colour photographs, made by the second author from various localities on the island of Cyprus and in southern Turkey. These photos showed a plant resembling typical Orobanche alba , but differing in several aspects. More pictures from other photographers and examination of herbarium material allowed a more detailed description of this plant:

Description: Stem simple, reddish-brown, with abundant pale glandular hairs, up to 26 cm tall, with abundant scales below and sparse scales above. Scales lanceolate, up to 17 mm long, glandular hairy, like the stem reddish-brown. Inflorescences cylindrical, lax, 12–17 × 3–4 cm, usually longer than the remaining stem. Bracts similar to the scales, lanceolate, glandular hairy, as long as the corolla tube to as long as the entire corolla. Calyx segments entire, from a lanceolate base long and narrowly acuminate, sometimes filiform, up to 11 mm long, one third to half as long as the corolla, with numerous glandular hairs and a darker middle vein. Corolla broadly tubular or campanulate, (16–) 18–20 mm long, its dorsal line rather straight in the middle part, but curved at the base and the upper lip (which is sometimes almost curved downwards), whitish at the base, getting darker towards the ± pale brownish-violet to reddish margin, most strongly coloured at the lobes of the upper lip (rarely the entire corolla dirty yellowish-white), with darker veins, outside with abundant yellowish glandular hairs, sometimes on the proximal (pale) part also with glandular hairs with dark red bases (e.g. Kalheber 97–437, Herbarium Kalheber); upper lip ± deeply 2-lobed, lobes broad, reflexed or more rarely antrorse; lower lip with 3 ± equal lobes, lobes round to almost truncate, irregularly crenate, between them two large ± light yellow folds, which run into the throat; all lobes more darkly veined, on the outer surface distinctly glandular hairy, on the inner surface with few glandular hairs, and on margins only sparsely glandular hairy. Stamens inserted 1–2 mm above the base of the corolla tube. Filaments basally dilatate, in the lower half long glandular lanate, in the upper half with sparse or scattered glandular hairs above. Anthers broadly elliptic, dark brownish in dry state, long whitish mucronate. Style (especially towards the stigma) reddish, like the upper part of the ovary abundantly glandular hairy. Stigma 2-lobed, white (sometimes after anthesis light pink).

Taxonomic relationship:— The plant differs from all other taxa of the Orobanche alba -complex [O. ser. Glandulosae Beck (1882: 132)] by the large, conspicuous light yellow folds between the lobes of the lower lip. Also remarkable is the absence of dark glands or darker hairs on the exterior of the corolla—as occasionally occurring also in other taxa of O. tribe Glandulosae , e.g. the taxon described as Orobanche alba f. lutescens ( Boreau 1840: 341) Beck (1890: 212) (a taxon clearly belonging to typical O. alba )—as well as the consistently white stigma.

A white stigma is also found in Orobanche alba f. cuprea (Boissier & Balansa ex Boissier 1879: 510) Beck (1890: 213) [syn.: Orobanche cuprea Boissier & Balansa ex Boissier (1879: 510) ], but neither Boissier & Balansa in Boissier (1879) nor Beck (1890) mentioned the yellow folds. According to the description by Beck (1890), („Corolla […] sicut tota fuscescentes-rubra.“) it is likely, that he has only seen a dry specimen of this plant or that he made his nomenclatural recombination without detailed consideration of the specimen. However, Boissier & Balansa (1879), probably describe characteristics of the fresh plant (e. g. the white stigma) and thus should have noticed the conspicuous yellow throat: “ O. cuprea breviter glanduloso-papillosa tota fuscescenti-rubra, caule squamis oblongo-lanceolatis obtusis obsito, spica longa laxa, bracteis a basi late lanceolata longe attenuatis subulatis corollam aequantibus, sepalis a basi latiori longe subulatis indivisis corollae subaequilongis, corolla tubuloso-campanulata dorso modice curvata labiis subaequilongis acute denticulato-glandulosis superiore retuso inferioris lobis obtusis intermedio submajore, filamentis paulo supra basin insertis inferne dilatatis et valde hirtis, stigmate albo. - Spica semipedalis vel fere pedalis, corolla 9 lineas longa, facies O. hederae floribus minoribus et characteribus caeterum diversissimae. Affinis O. epithymo spica brevi, stigmate atropurpureo, etc. distincte.” ( Boissier 1879: 510).

To determine whether Orobanche alba f. cuprea is the same as the plant described in detail above, the first author obtained scans of the syntypes located at the herbarium Conservatoire et Jardin botaniques de la Ville de Genève. The scans are of good quality ( Fig. 4 , 5 ) and clearly show the yellow folds on the lower corolla lip. Therefore, it is slightly puzzling that the feature was not included in the protologue. However, in all other respect the plants from Cyprus and southern Turkey fit well or at least do not contradict, the description of Orobanche cuprea , so that we are confident that these are identical.

Because of the distinctive morphological characteristics (absence of dark glandular hairs, yellow folds on the lower corolla lip and white stigma), the plant can be well distinguished from all other taxa of the O. alba -complex. Considering this fact and the existence of a separate distribution area this taxon is clearly undervalued as forma; the promotion (again) to the rank of species appears to be an overvaluation, because in its basic characteristics (habit, flower shape, ecology, etc.) it can be clearly seen as a taxon identical to typical O. alba . It is therefore classified as:

Figures

FIGURE 4. Syntype G 00330045 of Orobanche cuprea (courtesy of the herbarium Conservatoire et Jardin botaniques, G-BOIS). Lectotype (hic designatus) of O. alba subsp. cuprea (Boiss. & Balansa) Uhlich, C.A.J.Kreutz & Rätzel.

FIGURE 5. Syntype G 00330044 of Orobanche cuprea (courtesy of the herbarium Conservatoire et Jardin botaniques, G-BOIS).