Polygonatum costatum Floden, 2015

Floden, Aaron, 2015, A new Solomon’s Seal (Polygonatum: Asparagaceae) from northern Thailand, Phytotaxa 236 (3), pp. 279-282 : 279-281

Polygonatum costatum Floden sp. nov. ( Fig. 1 )

Differs from P. punctatum Royle ex Kunth in the whorled leaves at mid-stem; emaculate, non-urceolate, generally larger perigone, costate ridges of the perigone due to the raised areas where the filaments are connate within the tube; and the filaments longer. It also differs from P. tessellatum F.T.Wang & Tang in its shorter perigone, shorter filaments and anthers, as well as having multiple-flowered, pedunculate inflorescences (vs. single-flowered and fascicled). It is similar to both species in its erect infructescences, red fruit, and evergreen habit.

Type:— THAILAND. Chiang Mai Province: Java Tong District, summit area Doi Inthanon National Park , 2560 m, 24 May 1990, J.F. Maxwell 90-559 (holotype, BKF! ; isotypes CAS! , HUH! , MO! )

Plants perennial, evergreen. Rhizomes moniliform to torulose, green, densely fleshy rooted, 1–2 cm in diameter. Stem 30–50 cm tall, red maculate, cataphylls caducous, outermost ovate, inner lanceolate, apex obtuse, chartaceous. Leaves alternate to opposite proximally, 3–4 verticillate distally and at apex, 6–10 × 1–3 cm, oblanceolate, apex long acuminate, margin entire, glabrous, abaxially red maculate on midrib. Inflorescences 1 per leaf, 1–4-flowered, peduncles 5–10 mm long, pedicels 5–15 mm long, red maculate, bracteoles minute. Perigone cylindric, inflated distally around the point of filament insertion, distinctly costate on tube, 3 mm wide at pedicel, 4 mm wide near lobes, 8–10 mm long, white, lobes green, 2–3 mm long; filaments inserted near middle of perigone, 1–1.2 mm long, tapered distally, smooth to roughened, but not papillose, with a gibbous protrusion near anther attachment, anthers 1.5–2 mm long; ovary 2.5–2.7 mm long, style 2.2–2.7 mm long not surpassing the anthers; fruit red, ca. 1 cm diam., peduncles erect in fruit. Seeds ca. 1.5 mm, ovoid, tan.

Chromosome number:—2 n = 30. See Tamura (1993) who reported this count and its karyotype from plants from Doi Inthanon. In comparison to other members of the P. punctatum -group this species lacks a secondary constriction on the longest pair (see Floden 2014).

Phenology:—Flowering April–May, fruiting September–February.

Distribution:— Thailand: Chiang Mai Province; Doi Inthanon, 2300–2565 m. Epiphytic. This species should also be sought at higher elevations in the Daen Lao Range in southern Myanmar and into Yunnan, China. The apparent rarity of P. costatum may be an artifact of limited collecting and its discovery on Doi Inthanon only enabled due to access to the peak and increased biological collections from this national park.

Etymology:—The epithet, “ costatum ”, is for the distinctly costate ridges of the perigone where the staminal filaments are connate within the tube. These ridges are most prominent when the perigone is cut in cross section.

Conservation:—Doi Inthanon is a designated biosphere which is a protected area thus the plant does not qualify for protection ( IUCN 2014). At this time the species should be considered Data Deficient (DD) until locations are documented outside the biosphere.

Taxonomic relationships:—While the overall gross morphology and the cytology of Polygonatum costatum confirms its relationship with P. punctatum , there are abundant differences that serve to distinguish these species. Moreover, molecular analyses of the nuclear ribosomal ETS and ITS and chloroplast DNA support its relationship to the P. punctatum group and also its distinction from that species (A. Floden in prep.). In particular, in ETS there are 6 fixed differences that separate the two and a 4 bp duplication in P. costatum and in ITS there are 8 nucleotide changes.

Other specimen seen (paratype):— Chiang Mai Province: Java Tong District, summit area Doi Inthanon National Park , 2560 m, 1998, BSWJ 6599, living collection ( TENN) .

Figures

FIGURE 1. Polygonatum costatum, drawn from a living collection of BSWJ 6599, by the author. a, proximal portion of stem; b, perigone cut length wise; c, anther and filament. Scale bars, a = 1 cm for proximal portion of stem, a = 1 dm for whole stem and rhizome, b = 5 mm, c = 0.5 mm.