Mahonia lancasteri O. Colin, 2021

Colin, Olivier, Hinsinger, Damien Daniel & Strijk, Joeri Sergej, 2021, Mahonia lancasteri (Berberidaceae), a new species originating from Sichuan (China) described from cultivation, Phytotaxa 482 (1), pp. 45-54 : 46-50

Mahonia lancasteri O. Colin , sp. nov. ( Figs. 1 , 2 )

Type: — CHINA. Sichuan province: Hongya county, Zhangcun, Zhaobaoping , 1370 m, 19 October 1994, Og 94056 ( BGT), plants cultivated in Villemomble (Seine-Saint-Denis, France), grown from a cutting collected on 19 October 1994 at the type locality, O . Colin , J . Strijk, D. Hinsinger & R . Hinsinger BGT7000 (holotype BGT) .

Description:—Shrub up to 1.7 m tall (up to 2.2 m in cultivation). Trunk diameter up to 3 cm at base. Current year’s new shoots 1.7 cm in diameter. Bark cork-like, deeply furrowed. Leaves abaxially white pruinose (leaves 2‒3 years old becoming partially pruinose, revealing clear yellow-green surface), adaxially subglossy green, oblanceolate, 45‒68 × 19‒23 cm, apex acuminate; rachis pinkish yellow adaxially, green abaxially, section elliptic-oblong, 4 × 5 mm; rachis internodes 5‒10 cm, uppermost 5‒5.5 cm. Leaflets 5‒7 (‒9) pairs, obliquely arranged, remote, sessile, lowest pair 1‒2 cm above base of petiole, apex caudate. Venation reticulate adaxially, midvein and adjacent pair sunken, secondary and tertiary veins impressed; three main veins raised abaxially, secondary and tertiary veins visible, slightly raised. Leaflets of proximal pair widely ovate, 3.4‒5.4 × 4.3‒5.7 cm, margin spinose with two exserted teeth on each side. Leaflets of middle pairs ovate-lanceolate (orbicular-ovate in younger plants), 9 × 6 cm, 4‒5 (‒7) spinose exserted teeth on each side. Distal pair narrowly ovate, 9 × 4 cm, 7 spinose exserted teeth on each side. Terminal leaflet elliptic, 11.5‒13.5 × 3.7‒5.6 cm, 6 spinose exserted teeth on each side, petiolulate (petiolule 3.5‒4.6 cm). Inflorescence with subtending equilateral triangular bracts, 2 × 2 cm. Inflorescence of 18 to 25 ascending racemes, many with one or two tiers of branches at the base, sometimes with one or several short bifurcations near the apex. Racemes pseudo-paniculate, 23‒28 cm long, with up to 90 flowers. First pair of branches ca. 3 cm above proximal part; branches asymmetric in length (8.5‒12.5 cm vs. 5‒11 cm). Second tier of branches, when present, shorter (3‒4 cm long). Distal third of main racemes sometimes crooked, paniculate, comprising up to 8 secondary racemes, each 1.5‒2 cm long bearing 6‒8 flowers. Flower bracts in proximal or mid-part of main racemes very conspicuous, widely ovate to oblong-ovate, acute, 4‒7 × 3‒4 mm. Flower bracts on proximal pair of branches 2 × 1 mm. Flower bracts on distal pair of branches rounded, small, 1 × 1 mm. Main raceme section hemicylindrical or elliptic near base. Flowers faintly fragrant. Pedicel 6‒8 mm (longer than bracts). Outer sepals triangular-ovate, 2.3 × 2 mm. Median widely ovate, 3.1‒3.2 × 4.2‒4.3 mm, 5 veined. Inner obovate, 4.5 × 8.2 mm, 5‒veined. Petals spathulate-oblong, 7 × 4 mm, deeply emarginate, retuse to entire at apex. Nectaries present at base. Stamens 3.6 mm. Anther connective truncate to slightly rounded. Ovary slightly inflated proximally, style cylindrical, 4 mm, 1.3‒1.5 mm in diameter. Ovules 4‒5. Fruit deeply blue pruinose, style absent. Seeds 4‒5.

Phenology:—Flowering December‒March, fruiting April‒July.

Etymology:—The epithet is chosen in honor of Roy Lancaster, master plantsman and holder of a notable collection of Chinese Mahonia species in his garden at Chandler’s Ford, Hampshire, England. It is with appreciation that we note the taxonomic proximity of M. lancasteri and M. ogisui is mirrored by the longstanding friendship of their namesakes.

Distribution and ecology:— Mahonia lancasteri is currently known only from Hongya county (1370m) and Lezhi county (1350‒1450m) in west-central Sichuan, China. It grows on the margins of warm temperate forest.Among the notable species growing in the vicinity were Aucuba himalaica Hooker & Thomson (1855: XII), Berberis sp. , Camellia pitardii Cohen-Stuart (1916: 68) , Cotoneaster salicifolius Franchet (1885: 225) , Daphne acutiloba Rehder in Sargent & Wilson (1916: 539), Hydrangea aspera Buchanan-Hamilton ex Don (1825: 211) , Litsea populifolia Gamble in Sargent & Wilson (1914: 77), Mahonia ×emeiensis, M. gracilipes , M. nitens , Quercus oxyodon Miquel (1863: 114) , Schefflera delavayi (Franchet) Harms in Diels (1901: 486), Stachyurus chinensis Franchet (1898: 254) , Photinia davidiana Cardot (1919: 399) and Viburnum cinnamomifolium Rehder in Sargent (1907: ii 31) (M. Ogisu, pers. comm.).

Other individuals (though with fewer inflorescences) were found close to the above location in April 2012 by R. Lancaster and M. Ogisu while on a visit to Sichuan (see Fig.1 Q ). According to Lancaster (pers. comm.), several specimens were seen between 1350 and 1500 m growing in dense thicket, in association with Lonicera ligustrina var. yunnanensis Franchet (1896: 317) , Rosa longicuspis Bertoloni (1861: 15) , Berberis sp. , Litsea populifolia , Viburnum cinnamomifolium , Metapanax davidii (Franchet) Wen & Frodin (2001: 117) , Stachyurus chinensis , Cornus chinensis Wangerin (1908: 100) , Symplocos sumuntia Buchanan-Hamilton ex Don (1825: 145) , Rhododendron ririei Hemsley & Wilson (1910: 111) , a bamboo species, plus two other Mahonia , M. gracilipes and probably M. ×emeiensis, together with a rich herbaceous layer including Cardiocrinum giganteum var. yunnanense (Elwes) Stearn (1948: 4) and Hemerocallis lilioasphodelus Linnaeus (1753: 324) .

At Zhaobaoping, the exact type locality of our new species, M. Ogisu (pers. comm.) observed many intermediate forms between Mahonia nitens and M. gracilipes (= M. × emeiensis), some possibly involving more than these two species. More research is necessary to understand the precise taxonomic status of these plants. In fact, the question of hybridization among Mahonia in nature has yet to be addressed. It seems odd that, until now, only one nothotaxon has been described from the wild and none is mentioned in the recent floras whereas the propensity of Mahonia species to hybridize in cultivation is well known. Three artificial hybrids involving Chinese species have been named from cultivation: M. ×media Brickell (1979: 16) (= M. japonica Candolle (1821: 22) × M. oiwakensis Hayata (1916: 1)) , M. ×lindsayi Yeo (1972: 38) (= M. duclouxiana Gagnepain (1908: 87) × M. japonica ) and M. ×savilliana Shaw (2011: 46) (= M. eurybracteata Fedde in Diels (1901: 338) × M. gracilipes ). Others might be described in the future from specialized Mahonia collections or from Asian botanical gardens where self-sown hybrids are grown. For example, the first author’s collection contains self-sown hybrids of M. fortunei Fedde in Diels (1902: 130), M. nitens and M. bodinieri Gagnepain (1908: 85) . Mahonia lancasteri also appears to be able to hybridize in gardens with other cultivated species (see below History in cultivation).

Figures

FIGURE 1. Mahonia lancasteri. A. Habit. B. Leaf underside. C, D. Leaves of three different cultivated forms of M. bealei (left) and M. lancasteri (extreme right), adaxial (C) and abaxial views (D). E. Top of a main raceme showing bifurcations. F. Flower with some sepals removed. G. Stamen. H. Pistil. I. Infructescence. J. Young fruit showing immature seeds. K. Young plant with three simple racemes. L. Flowering raceme. M. Flowering raceme showing conspicuous bracts. N. O. Mature plant and inflorescences. P. Mature plant with inflorescences at bud stage. Q. Mahonia lancasteri, with Roy Lancaster (left) and Mikinori Ogisu in Lezhi county, Sichuan, China (2012). Scale bars represent 10 cm (A, B, C, D, K, N, O, P), 10 mm (A, B, C, D, M) or 5 mm (G, J, H). All photos by O. Colin except Q by John Massey.

FIGURE 2. Maximum likelihood cladogram (left) and phylogram (right) depicting the relationship of Mahonia lancasteri with related Mahonia species and Berberidaceae from Yu et al. (2017), based on nuclear ITS, accD, ndhF, rbcL and psbA-trnH. Phylogenetic position of the M. lancasteri sequence (holotype BGT7000) is highlighted in bold. Bootstrap values indicated above nodes, values below 50 not shown. M1: Moranothamnus Yu & Chung (2017). M2: Mahonia sect. Paniculatae Fedde (1901). For readability, outgroups branches are collapsed in the phylogram.