Polygonatum undulatifolium Floden, 2018

Floden, Aaron J., 2018, Polygonatum undulatifolium (Asparagaceae), a new species from the eastern Himalaya, Phytotaxa 374 (3), pp. 273-276 : 275-276

Polygonatum undulatifolium Floden sp. nov. ( Figs. 1 and 2 ).

Similar to P. cathcartii Baker (1875: 559) and P. griffithii Baker (1875: 558) in the opposite leaves and moniliform rhizomes, but differs from them by its distinctly undulate leaf margins, the obvious transverse leaf venation; it also differs from the former in its evergreen habit, and from the latter species by its shorter style not exserted from the perigone mouth.

Type:— INDIA. Arunachal Pradesh, East side of Siang River, heading from Tuting to Abroka Pass , ca. 7000 ft [ca. 2100 m], pressed from a cultivated collection, 29 May 2018, S. Hootman s.n. (holotype, CAL! , isotype MO! ).

Plant perennial, evergreen. Rhizome moniliform, 1–3 cm in diameter. Stem terete, red to purple maculate, smooth to minutely scabrellous, 40–200 cm tall, arching with upper half of stem often parallel to the ground. Cataphylls chartaceous, deciduous, borne on proximal third of stem, lanceolate-ovate, 3–12 cm. Leaves petiolate, petioles 1–5 mm. Leaves opposite, narrowly to broadly lanceolate, 8–15 cm long × 3–8 cm wide, chartaceous, base rounded, apex acute, generally 3-veined with secondary transverse veins prominent even when living. Inflorescences axillary borne in lower leaf axils; 1–3-flowered; peduncle arcuate 2–5 cm long, pedicels 1–1.5 cm, bracteoles subulate, cauducous or withering. Perigone 1–1.6 cm, expanded distally around the filaments; creamy white-yellow and green, occasionally with faint reddish tessellation proximally on outside of tube. Filaments inserted near middle or just distal of middle; 2–4 mm, sigmoid complanate, thicker distally with a distinct gibbous swelling at attachment to anther, papillose with longer papillae on the dorsal side; connivent around stigma; anthers subequal. Ovary green, elliptic, 3–4 mm; style subequal, not exserted from mouth of perigone. Fruit spherical, red; 1–2 cm diam.; seeds spherical 1–2 mm diam.

Etymology:—named for the distinctly undulate margined leaves which are distinct from all sympatric taxa.

Distribution:—This species is endemic to China (Tibet, near Medog) and India (Arunachal Pradesh, East Siang District), at altitudes ranging from 1900 to 2400 metres.

Ecology:— Polygonatum undulatifolium in Arunachal Pradesh, India was found as growing terrestrially in subtropical broad-leaved evergreen forests on steep slopes with Musa , Hedychium , with canopy trees including Lithocarpus , Schefflera , Rhododendron , and others. Specimen collection data and field images of the plant (cfh.ac.cn) show it also occurring in Tibet, China at a similar elevation range.

Phenology:—Flowering in May–June, fruiting September–November.

Other specimens examined (paratypes):— CHINA. Tibet. Medog, 25 August 1974, Qinghai-Tibet team 74-3988 ( PE01532391 !) ; ibidem, 3 August 1974, Qinghai-Tibet team 74-3988 ( PE0622106 !) ; ibidem, 2200 m, 28 June 1980, W. Chen 10694 ( PE01376532 !, 01376533 !) ; ibidem, 2000 m, June 1993, H. Sun, Z.K. Zhou, and H.Y. Yu 4301 ( KUN761864 digital image) ; ibidem, Han Mi, 1800 m, 28 October 1992, H. Sun, Z.K. Zhou, and H.Y. Yu 937 ( KUN305598 , 305600 digital images) ; INDIA. Arunachal Pradesh, above Simong Village, ca. 2000 m, Floden, Bruggeman, & Prehsler s.n., photo only ( Figs. 1c–d & 2 ) ; Pemako, ca. 1900 m, Bruggeman, photo only (Fig. 3) .

Taxonomic relationships:— Polygonatum undulatifolium is very similar to terrestrial forms of P. cathcartii in general appearance with opposite leaves that are glaucous abaxially, but it differs in its evergreen habit, transverse leaf veins, strongly undulate leaf margins, stem maculation color, and perigone morphology. The stems are maculate in large irregular purple maculation (vs. reddish maculation) on the lower part of the stem and sometimes completely coloring the proximal portion of the stem. The perigone is larger and more white-green in color than that of P. cathcartii which is typically yellow or yellow-white. The proximal portion of the perigone in P. undulatifolium often has some faint reddish tessellation in some populations. Polygonatum undulatifolium is also similar to P. griffithii but that species differs in its non-undulate leaves, its absence of obvious transverse veins, and by the length of its style that is up to three times the length of the ovary and exserted from the mouth of the perigone. Polygonatum undulatifolium has a style that is subequal in length to the ovary, but unlike P. cathcartii , the ovary is oblong-ovoid vs. spherical. The filaments of P. undulatifolium and P. cathcartii are inserted just distal of the middle of the perigone tube, but the two differ in multiple characters: the pedicels of P. undulatifolium are minutely papillose distally and glaucous, but scabrellous in ridges proximally whereas P. cathcartii are papillose and glaucous without the scabrellous ridges.

The treatment of Polygonatum griffithii in the Flora of China ( Chen & Tamura 2000) is largely based upon collections of P. undulatifolium from southeastern Tibet and no specimens were seen by Tamura ( Chen & Tamura 2000). Its inclusion in the flora is likely based on the Flora of Xizang ( Wu 1983). Examination of specimens at PE! and the elevations at which the specimens were collected reveals that all specimens referred to as P. griffithii in China are in fact P. undulatifolium and that the relatively unknown P. griffithii , which is known only from its type collection, should be excluded from the flora of China. The description of P. undulatifolium raises the number of species in the genus to 81 ( Floden 2015, WCPS 2018).

Early collections of the new species in fruiting stages were documented from Tibet near the border of India and these did not enable comparison to related species. Recently, I observed this species in Arunachal Pradesh, India above the Siang River at similar elevations as those collected in adjacent China further north along the river in flower and these enable comparison to sympatric populations of P. cathcartii . The types originated from this same region which is a hotspot of biodiversity within the Himalayan region ( Chowdhery 1997) and is comparatively underexplored. It is likely that P. undulatifolium is endemic to this region of the Mishmi Hills since it has not been observed by myself further to the east near Mayodia in similar habitats during field excursions nor have specimens other than those cited above been observed.

Figures

FIGURE 1. Polygonatum undulatifolium photographed by P. Bruggeman (A), a close up of a filament showing the shape, insertion, and surface of characters (B), and in situ by the author (C, D) at approximately 2000 metres, Arunachal Pradesh, India, showing: C, the inflorescences borne only in the lower axils of the stems, the white-green perigone; and D, the arrows indicate the small cauducous subulate bracteoles, and a dissected perigone showing the sigmoid complanate filaments and their insertion level, and the subequal style and ovary; perigone approximately 1.5 cm long and 0.5 cm wide at its widest point.

FIGURE 2. Polygonatum undulatifolium, photographed in situ inArunachal Pradesh by the author,bottom, showing the distinctly undulate leaf margins, the evident secondary transverse veins, and top, the glaucous abaxial surface, and the purple-maculate stem.