Gastrodia Brown (1810: 330)

Averyanov, Leonid V., Nguyen, Van Canh, Vuong, Truong Ba, Quang, Bui Hong, Nguyen, Khang Sinh, Le, Tuan Anh, Binh, Tran Duc, Maisak, Tatiana V. & Nguyen, Cuong Huu, 2025, New orchids in the flora of Vietnam X (Orchidaceae, Orchidoideae, tribe Orchideae, Epidendroideae, tribes Gastrodieae, Arethuseae, Cymbidieae, and Vandeae), Phytotaxa 681 (1), pp. 20-54 : 24-26

Gastrodia Brown (1810: 330) .

Gastrodia fontinalis T.P. Lin (1987: 129 , photos 72, 73), Su (2000: 894, fig. 380), Chen et al. (2009: 204), Lin et al. (2016: 99).

( Fig. 2 )

Type: — CHINA. Taiwan: Taipei, Mt. Pataoerh, February 25, 1979, Lin 435 (holotype TAIF, fide Lin et al. 2016: 99).

Ecology and phenology (in Vietnam):—Achlorophyllous mycoheterotrophic tuberiferous herb. Lowland evergreen broad-leaved closed forests on stratified solid shale, commonly along streams, at elevations of about 100 m a.s.l. Flowers in November–December.

Distribution: — Vietnam (Quang Tri Province, Da Krong District). Japan, China (Taiwan).

Conservation status:— Gastrodia fontinalis is presently known from a single location with one population in lowland area of Quang Tri Province (Da Krong District). This area has no official protection and experienced the wide uncontrolled anthropogenic transformation, resulting in decline in quality of the habitat. The AOO is less than 10 km 2. Owing to the fact that this is a mycoheterotrophic species and based on threat of ongoing decline in quality of habitat, the species can be assessed as Critically Endangered [CR B2ab(iii)] following formal criteria proposed by the IUCN (2024). The species is known to occur in Taiwan and Japan. Hence, due to such disjunct distribution range, the immigration of propagules from these countries is highly unlikely. In Japan this is considered as a very rare species ( Suetsugu et al. 2014). Accordingly, the preliminary assessment of CR is retained for the final regional assessment of this species for Vietnam.

Notes: —Plants discovered in central Vietnam (in Quang Tri Province) in their morphology fit well with Taiwanese plants described under the name Gastrodia fontinalis ( Lin 1987) . We have no doubts in their identification. Similar plants were discovered recently also from the Ryukyu Islands of southern Japan ( Suetsugu et al. 2014). Both discoveries outside Taiwan anticipate a wide distribution of this unattractive achlorophyllous species, which was previously considered as a strict Taiwanese endemic. The location of the species, which was unexpectedly found in Vietnam, is more than 1500 km on the west-south-west from locus classicus and exhibits a significant ocean disjunction. Meanwhile, Vietnamese plants differ from Taiwanese specimens by not spreading perianth (vs. spreading perianth) and raceme-like inflorescence (vs. head-like inflorescence), and may represent local mainland race.

Studied specimens: — VIETNAM, Quang Tri Province, Da Krong District, Trieu Nguyen Commune, lowland evergreen broad-leaved closed forest on stratified solid shale, along stream, around point 16°40’33.9”N 106°59’14.7”E, at elevation about 100 m a.s.l., 8 December 2023, Tuan Anh Le, AL2808 (analytical photos LE: LE 01124749 https:// en.herbariumle.ru/?t=occ&id=208857).

Figures

FIGURE 2. Gastrodia fontinalis. A. Flowering plants in natural habitat. B. Flattened flowering plants prepared for herbarization. C, D. Portion of rhizome. E. Rhizome, cross section. F. Flowers buds in apical part of inflorescence. G. Portion of inflorescence. H. Floral bract, abaxial side. I. Rachis, floral bract, pedicel and ovary, and flower but, side view. J. Flowers, front view. K. Flower with dissected lateral sepals, view from below. L. Flower with separated lateral sepal and petal, side view. M. Column and intact lip, side view. N. Column and lip artificially recurved. O. Intact lip, view from below. P. Artificially recurved lip, view from above. Q. Separated lip, abaxial side. R. Column, frontal and half-side views. S. Apex of column with intact anther. T. Base of column, adaxial side. U. Operculum, view from above and from below. V. pollinarium. W. Ovary, cross section. Photos by Tuan Anh Le, from specimen AL2808. Photo correction and design by L. Averyanov and T. Maisak.