Viburnum treleasei Gandoger (1899: 255)

Moura, Mónica, Carine, Mark A., Malécot, Valéry, Lourenço, Paula, Schaefer, Hanno & Silva, Luís, 2015, A taxonomic reassessment of Viburnum (Adoxaceae) in the Azores, Phytotaxa 210 (1), pp. 4-23 : 17-18

Viburnum treleasei Gandoger (1899: 255)

Type (lectotype designated here):—AZORES. Flores: 4 August 1894, Trelease 389 (MO1679100!, isolectotype AZ 1336!).

≡ Viburnum tinus L. var. subcordatum Trelease (1897: 118) ≡ Viburnum tinus L. subsp. subcordatum (Trel.) P. Silva in Palhinha (1966: 115−116) ≡ Viburnum subcordatum (Trel.) Rivas-Martínez et al. (2002: 709) , nom. superfl.

− “ Viburnum tinus ” auct . non Linnaeus (1753: 267−268): Seubert & Hochstetter (1843: 13).

− “ Viburnum tinus L. var. lucidum ” auct. non ( Miller 1768: VIB-VIB) Aiton (1789: 372): Seubert (1844: 35).

Note:—We consider that V. treleasei Gandoger is a name at a new rank (stat. nov.) for V. tinus var. subcordatum , thus following Art. 7.3 of ICN, its type should be selected among the material cited by Trelease (1897). Trelease (1897) cites four specimens collected by himself in the Azores (São Miguel: 25 August 1894, Trelease 388, MO!; Flores: 4 August 1894, Trelease 389, MO! AZ!; Flores: 10 August 1894, Trelease 390, MO!; Santa Maria: 29 June 1896, Trelease 390a, MO!, idem, Trelease 390b, MO!), together with a Carreiro specimen “San Miguel (388; Carreiro)”. The only Carreiro collections older than the protologue that match are deposited at LY and AZ: Carreiro s.n. (São Miguel: Furnas, July 1891, at LY! [in Gandoger’s herbarium]), Carreiro s.n. (São Miguel: Furnas, July 1891, at AZ! [1331, V. lucidum sensu H. Christ ]). From among these syntypes, Trelease 389 is selected as lectotype. It is a mature fruiting collection, distributed at both MO, where Trelease worked, and AZ.

Both Gandoger (1899) and Trelease (1897) cite the names Viburnum tinus and V. tinus var. lucidum in synonymy. For Viburnum tinus, Gandoger (1899) clearly stated “non L.”, thus he explicitly excluded Linnaeus’ type. This was not the case for V. tinus var. lucidum . However, we consider that their inclusion in synonymy is to record names previously used in the Azores to refer to the taxon described by Trelease (and renamed by Gandoger). Gandoger (1899) considers Viburnum treleasei as endemic to the Azores, thus excluding the type V. lucidum Mill. (basionym) and V. tinus var. lucidum (Mill.) Aiton by implication [Art. 52.2(e)]. Viburnum lucidum was first reported by Clusius (1576) from Portugal, and cultivated in mainland Europe [as indicated by Oersted (1861) in his monograph of Viburnum ]. We also note that Gandoger considered V. lucidum as a distinct taxon from southern Europe, in his Flora Europae [ Gandoger, 1886: 40, as “Tinus lucidus (Mill.)], a work that he mentions in the introduction of his 1899 article containing the V. treleasei protologue, and in his Novus Conspectus Florae Europae ( Gandoger 1910: 225, as Viburnum tinus subsp. lucidum ), leaving no place for including its type under V. treleasei .

Evergreen shrub up to 2 m tall, with dense, ovate canopy and pubescent twigs with stellate trichomes, the most apical internodes slightly compressed. Leaf 3−10 × 2.5−6 cm, bright green, subcoriaceous, entire, ovate, obovate, orbicularovate or elliptic; base mostly subcordate or auriculate-cordate; apex acute or obtuse; margins revolute; venation pinnate, with secondary veins curving, not ending in margins, and anastomosing; blade surface blistered; upper leaf surface with simple pilose trichomes located on the mid rib and secondary veins; lower leaf surface with dense long tomentose trichomes on the mid rib and secondary veins axils, simple hirsutullous trichomes and occasional, small sessile stellate hairs, on the mid rib and secondary veins, trichome density variable with near glabrous forms occurring frequently. Petiole 0.5−4 cm in length, hemicylindrical, with simple trichomes on the upper surface and stellate trichomes on the lower. Inflorescence 4.5−7 cm wide, umbelliform. Peduncles with one axillary bract; primary peduncle very short, generally with less than 1 cm long, branching into 5−7 primary rays; secondary and tertiary peduncles 0.9−2.1 and 0.5−1.3 cm, respectively, branching into 4−6 secondary rays and pedicels. Pedicel 0.2−0.6 cm, with 1 axillary bract and 2 terminal bracteoles. Calyx 5-merous, herbaceous, funnelform, synsepalous, fused with the ovary, persistent. Corolla diameter 5−9 mm, actinomorphic, rotate, 5-merous, synpetalous, marcescent, white inside with pink or red streaks outside. Stamens 5, excerted, filament glabrous. Pollen exine with regular reticulum and psilate muri. Ovary inferior, with long, stellate trichomes at the base, 1-locular, excentric, with one fertile locule, 1-ovulate, matted with long fascicled hairs. Style less than 1 mm long, glabrous, or sessile. Stigma 3-lobed, generally pink. Fruit subglobose pseudodrupe with thin flesh, 7−11 cm long, metallic-blue. Stone generally moderately compressed in cross-section, slightly grooved. Endosperm ruminate. Glands upright with rounded apex on the inflorescences, mid rib and secondary veins of the upper leaf surface, less frequently on the lower leaf surface.

Phenology:—Flowering occurs from November to June, with inflorescences showing diminute dark red flower buds, which grow and open into white or white and pink streaked flowers. Fruiting occurs from May to February, with fruits initially bearing a green colouration and later turning a characteristic metallic-blue shade when ripe. Seedlings emerge from March to August. Annual growth develops from March to July.

Distribution and Habitat:—Native in all Azorean islands, except Graciosa, where it was recently translocated from other islands. Generally found in non-shaded locations, either on the margin or in clearings of natural forests ( Morella faya woodland, laurel forest, Ilex perado subsp. azorica forest, Juniperus brevifolia forest, Erica azorica forest), on Erica azorica scrubland, Holcus rigidus natural meadows, pioneer scrubland, roadsides and on ravines and crater slopes, generally between 300 to 800 m, although altitudinal limits can reach below 100 m ( Flores) and above 900 m (Pico).