Gastrodia putaoensis X. H. Jin, a newly recorded species of Gastrodia from China

Gastrodia, a large genus of leafless myco-heterotrophic orchids^[1], comprises approximately 90 species and is distributed throughout Africa, tropical Asia, China, Japan, Madagascar, and Oceania^{[2, 3]}. In the past 14 years, numerous new species of Gastrodia have been reported globally, with several first reported in China^[4-9]. Gastrodia can be distinguished from other orchids by its myco-heterotrophic habit, horizontal and slightly fleshy rhizomes, terminal inflorescence, campanulate, urceolate, or cylindric flowers, united sepals and petals forming a perianth tube, with only apical portions free, and two pollinia without a caudicle^[10].

Gastrodia putaoensis X. H. Jin was first discovered in the Putao District, Kachin State, Myanmar, in 2016^[11]. This species is characterized by terminal sparse inflorescences, white flowers with sepals and petals united and forming a perianth tube, petal lip bifurcated into two sections, with the narrow apical section densely covered with yellow hairs and the apex densely covered with red papillae. In 2022, during a field investigation in Motuo County, Xizang, we discovered a whitish, flowering Gastrodia species growing under an evergreen broadleaf forest, consistent with the habitat described in Myanmar^[11]. Upon careful examination of the floral anatomical structure and consultation with related taxonomic literature, it was determined that this species was G. putaoensis, thereby confirming its presence as a new record for China.

墨脱天麻（新拟，Fig. 1: A–K）

Figure  1.  Gastrodia putaoensis X. H. Jin

A: Habit; B: Plant; C: Rhizome; D: Inflorescence; E: Flower; F: Sepals and petals; G, H: Location of column and lip; I: Anther cap; J: Column (without anther cap); K: Inner and outer surface of lip.

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Gastrodia putaoensis X. H. Jin, Nordic Journal of Botany, 35(6): 730–732, 2017.

Type: Myanmar, Kachin State, Putao District, Hkakaborazi National Park, Jin Xiaohua, et al., PT-2275 (holotype: PE; isotypes: PE, IBSC).

Myco-heterotrophic herb, 20−45 cm tall. Rhizome horizontal, 3–10 cm long, cylindric, slightly fleshy with several spreading roots. Stem glabrous, slender, and upright, without green leaves. Inflorescence terminal, sparse, 5–15 cm long. Floral bracts ovate, membranous, with purple apex. Flowers slightly twisted, pendent, white, ca. 15 mm long. Sepals and petals united, forming a perianth tube, more or less campanulate; Lobes 5, sepal lobes 3, broadly triangular-ovate, subequal, ca. 3 mm long, entire, apex obtuse, with verrucae or papillae between lobes; petal lobes 2, 3×2–2.5 mm, entire, apex acute. Petal lip enclosed within perianth tube, adnate to apex of column foot, ca. 5.5 mm long, 5-veined, veins sunken into 5 channels on the upper surface; basal part ovate, with short claw, 3.5×2–2.5 mm, 2 calli occurring on claw, yellow and sub-globose; apical part constricted, 2–2.2×0.8–1 mm, densely covered with yellow hairs, obtuse at apex, densely covered red papillae. Column contains winged sides, with two long and erect teeth at apex; pollinia 2, granular-farinaceous, composed of friable massulae, without caudicles, borne on anther cap; stigma raised, light green.

Distribution and habitat: North Myanmar (Kachin) and southwest China (Xizang), found growing under montane evergreen broadleaf forests.

Voucher specimen: China, Xizang, Nyingchi Prefecture, Motuo County, Beipeng Township, under montane evergreen broadleaf forest, 29.25°N, 95.22°E, 31 May 2022, Hu Guangwan, et al., HGW-1625 (HIB).

Phenology: Flowering in May and June.

Discussion

The complex terrain and climate of Xizang have created a remarkable diversity of plants. 116 genera and 491 species of wild orchids were reported as of 2022^[12], followed by 2 genera, including 29 new records and new species in 2023^[13-16], suggesting a high likelihood of discovering new orchid species in Xizang. Gastrodia putaoensis, first discovered in Myanmar, was subsequently discovered in southern Xizang as a newly recorded species in China. The two sites, located in the southern region of the Himalayas, are only 300 km apart and share similar terrain and climate. The original description provided only photographs of the habitat and inflorescence of the species, without detailed photographs of the floral anatomy and rhizome^[11], which are included here.

Compared with other Gastrodia species, the lip of G. putaoensis serves as a key identifying characteristic. The lip is bifurcated into two sections, consisting of an ovate basal segment and a narrower apical segment. The apical part is densely covered with yellow hairs, while the apex is densely covered with red papillae. In contrast, species such as G. dyeriana, G. longitubularis, G. gracilis, and G. wuyishanensis are characterized by lips comprised of only a single segment^{[2, 8, 9, 11]}. Furthermore, G. menghaiensis exhibits a lip with two sections of varying widths, similar to G. putaoensis, but features a long claw and lacks distinctive yellow hairs and red papillae^[7].

Gastrodia exhibits distinctive saprophytic traits, and its floral structure displays notable variability. Nevertheless, despite extensive research efforts, the phylogenetic history and biogeography of Gastrodia remain poorly understood. Further investigations are needed to unravel the complex evolutionary patterns of this unique genus. The recent discovery of G. putaoensis in China provides a valuable addition to the exploration of the origin, evolution, and phylogeny of this genus.