Polygonatum campanulatum G.W.Hu, 2015

Cai, Xiu-Zhen, Hu, Guang-Wan, Kamande, Elizabeth Mwihaki, Ngumbau, Veronicah Mutele & Wei, Neng, 2015, Polygonatum campanulatum (Asparagaceae), a new species from Yunnan, China, Phytotaxa 236 (1), pp. 94-96 : 94-96

Polygonatum campanulatum G.W.Hu , sp. nov. ( Fig. 1 ).

The new species differs from Polygonatum gongshanense by alternate phyllotaxy, lamina shape, campanulate perigone, adnation of the peduncle base to stem and obovoid ovary; from P. franchetii in having epiphytic habit, subulate bracts, part of the peduncle adnate to stem, campanulate perigone and obovoid ovary.

Type:— CHINA. Yunnan Province: Xima Town , Yingjiang County, on the trunks of large trees mixed with epiphytic mosses and ferns in tropical mountain rainforest, 24°47′N, 97°40′E, elev. 1500 m, 27 October 2011, G. W. Hu HGW-00905 (holotype, HIB!; isotypes, HIB!, HNNU!)

Perennial, epiphytic herbs. Rhizome subglobose, dorsiventrally compressed, 2.4–4.1 cm in diameter, several ones connecting head to tail into moniliform rootstock with many fleshy roots. Stem ascendant, arching, 58–72 cm long, simple, glabrous, ca. 1.5–6 mm in diam., green, sometimes with black sparse dots at lower part. Leaves 6–12, alternate, simple, leaf lamina green to olive green, lustrous, narrowly lanceolate or elliptic-lanceolate, apex caudate, base cuneate, margin entire, glabrous, 12–16.8 cm long, 2.1–3.2 cm wide, petiole short, 2–3 mm long, glabrous. Inflorescences 2–3-flowered, peduncle pendulous, 2.5–4.2 cm long, basal 7–13 mm adnate to stem. Pedicels 8–18 mm long, bracts subulate, ca. 1.5 mm long, membranous, borne about middle of pedicel. Flowers bisexual, actinomorphic, pendulous; perigone yellowish green, or greenish white, 13–20 mm long, campanulate, tube 11–15 mm long, constricted around the ovary in the proximal third, lobes 6, ellipticovate, 4–6 mm long, 4–5 mm wide, apex acute; stamens 6, adnate to perigone tube; filaments incurved and connivent around the stigma, 4–4.5 mm long, inserted approximately at the middle of perigone tube, cylindrical, introrse, apex with a retrorse spur, spur 2–2.5 mm long, papillose; anthers lanceolate, yellowish white, 4–5 mm long, 1–1.2 mm wide, apex acute, 2- loculed, longitudinally dehiscent; ovary obovoid, sessile, 4.5–6 mm long, glabrous, 3-loculed, style 5.5–7 mm long, stigma glabrous. Fruit a berry, young fruit obovoid, ca. 6 mm in diameter. Pollen grains are single, navicular in equatorial view, bilateral symmetry, monocolpate, perforate reticulate ornaments and 42.8–45.9 × 18.9–20.2 μm in size. Shape and size of mesh irregular.

Distribution:— China (narrowly endemic and only known from the type locality, i.e. Xima Town, Yingjiang County, western Yunnan, China).

Ecology and Habitat:—All plants grow epiphytically on large trees in old-growth forests in a narrow altitude range. During the course of field work, we did not find any other population of this new species around the type locality (about 5 km 2). A single population of fewer than one hundred individuals was observed in an area of 25 km 2. Survey of the adjacent forests and long-term monitoring of the type locality is required to obtain more information about this species.

Phenology:—Flowering October.

Etymology:—The epithet ‘ campanulatum ’ refers to the campanulate shape of the perigone.

IUCN Red List Category:— Polygonatum campanulatum is only found from Xima Township, Yingjiang County, western Yunnan, China. According to the IUCN Red List protocol ( IUCN 2010), we categorize Polygonatum campanulatum as Critically Endangered (CR B1a, b(v)).

Taxonomic relationships:— Polygonatum campanulatum is unusual in its filaments apex with a retrorse spur; only two species of Polygonatum in China have this character, i.e. P. gongshanense Zhao & He (2014: 333) and P. franchetii Hua (1892: 392) . Polygonatum gongshanense , endemic to the Gongshan County, is also epiphytic. However, P. campanulatum has many obvious differences to distinguish it to P. gongshanense including the stem, which is green, sometimes with black sparse dots at lower part (vs. pink, minutely white-spotted in P. gongshanense ), the leaves which are alternate, lamina is narrowly lanceolate or elliptic-lanceolate with caudate apex and cuneate base (vs. leaves opposite, lamina ovate or lanceolate with attenuated apex and obtuse base in P. gongshanense ), the peduncle whose basal part is adnate to stem (vs. axillary in P. gongshanense ), the shape of the perigone, which is campanulate (vs. cylindrical in P. gongshanense ), the ovary shape which is obovoid (vs. cylindrical, apex trifid in P. gongshanense ). Polygonatum campanulatum is also similar to P. franchetii in the spur structure of filament apex, but differs most strikingly in the epiphytic habit (vs. epigeous in P. franchetii ), the peduncle whose basal part is adnate to stem (vs. axillary in P. franchetii ), the subulate and small bract, which borne about 1/2 of pedicel (vs. 2 or 3, bracteate at base of pedicel, large, enclosing flower bud in P. franchetii ), the campanulate perigone (vs. cylindrical in P. franchetii ) and obovoid ovary (vs. elliptic in P. franchetii ).

Figures

FIGURE 1. Polygonatum campanulatum sp. nov. (A) Habitat; (B) Rhizome; (C) Inflorescences; (D) Flowers in front view; (E) Adaxial (left) and abaxial (right) leaf blades, young friuts; (F) Flowers in lateral view, showing the shape of perigone; (G)–(H) Anatomical structure of flowers; (I) Stamen, showing the spur of filament apex. Photographed by GUANG WAN HU from Yingjiang, Yunnan.