A REVISION OF GAGNEPAINIA AND HEMIORCHIS (GLOBBEAE: ZINGIBERACEAE)

The species of Gagnepainia K.Schum. and Hemiorchis Kurz are revised throughout their ranges. These genera are shown with evidence from morphological and molecular studies to be distinct, although closely related to each other. Two species of Gagnepainia and three of Hemiorchis are recognised. A key to the genera of Globbeae and keys to the species of Gagnepainia and Hemiorchis are given, all names are typified and descriptions are provided. Conservation assessments of all taxa are proposed.

). This analysis, which included three accessions of Gagnepainia and four of Hemiorchis, sequencing internal transcribed spacer (ITS) and matK from each, found the two genera to be closely related as sister taxa and strongly supported as a monophyletic group. They share similarities in vegetative and floral characters that confirm this relationship (Table 1). In particular, the complex structure and ornamentation of the central region of the labellum is believed to be a unique and powerful unifying character of the two genera (Williams et al., 2004). Species delimitation and application of names in each genus remain largely unclear, however, so the aims of this work are to carry out a taxonomic revision using all available materials.

T A X O N O M I C H I S T O R Y
Kurz first established Hemiorchis with a single species, Hemiorchis burmanica, from Burma in 1873. In 1894, King added a second species from Sikkim, Hemiorchis pantlingii King. Baillon described three more species in 1895, Hemiorchis godefroyi Baill., Hemiorchis harmandii Baill. and Hemiorchis thoreliana Baill. from materials said to have been collected in Cambodia. He noted that these three species were unlike the type species, Hemiorchis burmanica, differing significantly in floral characters such as floral tube length and labellum morphology. Schumann (1904), in the most recent worldwide monograph of the Zingiberaceae, described another species of Hemiorchis, H. rhodorrhachis K.Schum. This new taxon had been described and illustrated as Hemiorchis burmanica by J.G.Baker (1890, tab. 7120) from cultivated material at the Royal Botanic Gardens, Kew.
Although the numbers of species in these genera are small, the identity of each species is unclear (Leong-Škorničková, 2009), and in some recent works, names have been applied interchangeably to the species, particularly in Gagnepainia (Phạm, 2000;Larsen & Larsen, 2006;Leong-Škorničková, 2009;Picheansoonthon & Tiyaworanant, 2010). A detailed study of the type materials is necessary in order to resolve this question.

M A T E R I A L S A N D M E T H O D S
Specimens or digital images of specimens were obtained from BK, BKF, CAL, CMU, E, K, L, P, U and US, which hold substantial collections from the Indochinese Continental Region, including type specimens cited in protologues. Eighty-one herbarium specimens of Gagnepainia were examined, 41 of them as digital images only. Forty-nine herbarium specimens of Hemiorchis were examined, 23 of them as digital images only. Additionally, living plants in the collection of the Royal Botanic Garden Edinburgh (RBGE) were studied ( Table 2). To manage all the data recorded from the specimens, information was added to the Zingiberaceae Resource Centre (continuously updated), an electronic database relating to Zingiberaceae that is maintained by the fifth author. The database is populated by the PADME system (Miller et al., 2015), which was developed at the RBGE. This revision has largely been put together using reports (e.g. annotations, citations of specimens studied in geographical sequence) generated by PADME. Mapping was done using the program DIVA-GIS (Hijmans, no date), based on geographical data downloaded from PADME.
Conservation assessments of the taxa were carried out according to the IUCN Red List Categories and Criteria, version 3.1, second edition (IUCN, 2012).
The morphological species concept is adopted in this revision. Each species is defined by an assemblage of characters derived from observing and measuring herbarium specimens and living plants in cultivation.
Throughout the growing season of 2013, living plants at RBGE were observed from their emergence from dormancy through flowering and fruiting (achieved by hand pollination in some accessions), to new vegetative growth and dying back again late in the season. The flowers were dissected and observed under a binocular dissecting microscope, and the development and dehiscence of fruits of some plants were also observed and recorded. The roots, tubers, rhizomes and leafy shoots of mature plants were studied. During the growing season of 2019, further hand pollinations were carried out in order to produce fruits.
The accessions sampled are listed in Table 2. Because all available sequences of Gagnepainia and Hemiorchis in the National Center for Biotechnology Information (NCBI) GenBank were either duplicates of those growing at RBGE or else poorly documented or not available to us, we decided not to use them and proceed only with material we have seen. Seven species of the closely related genus Globba, representing most sections, and three outgroup species, two from the subfamily Zingiberoideae (Boesenbergia rotunda (L.) Mansf. and Curcuma rhabdota Sirirugsa & M.F.Newman) and one from the subfamily Alpinioideae (Alpinia galanga (L.) Willd.), were included, i.e. sequences were downloaded from NCBI GenBank. Two regions were sequenced: ITS and matK.
A large-scale phylogenetic study of the Globbeae, especially Globba, is under way, and results will be published by the third author and colleagues in due course. The simple null hypothesis being tested here was that the species sampled do not fall into more than one clade, i.e. that Gagnepainia and Hemiorchis are one genus.

DNA extraction and sequencing
Total genomic DNAs were extracted using DNeasy Plant Mini Kits, available from Qiagen (Maryland, USA). Two regions were selected for amplification, namely nuclear ITS and chloroplast matK. PCR amplifications of these regions were performed using BIOTAQ DNA polymerase from Bioline (London, UK), with bovine serum albumen as an enhancer. PCR products were purified using ExoSAP-IT, supplied by Affymetrix (California, USA), and sequencing reactions performed using the BigDye Terminator v3.1 Cycle Sequencing Kit from ThermoFisher Scientific (Massachusetts, USA). Sequencing primers were the same as the amplification primers. Samples were sent to Edinburgh Genomics (Edinburgh, UK) for sequencing. See the Appendix for the primers, PCR recipes and PCR profiles used. Raw sequences were assembled and edited using Sequencher 5.1 (Gene Codes Corporation, Michigan, USA).

Phylogenetic analysis
The alignment was made using MAFFT v.7.394 (Katoh & Standley 2013), then checked and improved manually in BioEdit v.7.0. 4.1 (Hall, 1999). A partition homogeneity test (incongruence length difference, ILD, test;Farris et al., 1994) was performed in PAUP* 4.0 (Swofford, 2002). Nuclear regions were compared with chloroplast regions and easily passed the ILD test (P = 0.93). This result suggests that there is not a significant difference in the evolution of nuclear and chloroplast regions, and hence both may be concatenated and analysed together with partitioned analysis. The best evolution model of nucleotide substitution was computed using jModelTest 2.1. 3 (Guindon & Gascuel, 2003;Darriba et al., 2012). The GTR+G and GTR+I model was selected as the best-fit model (based on AIC; Akaike information criterion) for the ITS and matK data set, respectively.
Two phylogenetic reconstruction methods with partitioned data set were applied.

Characters
Life form. All species of Gagnepainia and Hemiorchis are deciduous herbs. They are dormant during the dry season and sprout at the onset of the rainy season.
Root zone. Gagnepainia produces compact rhizomes, similar to those of many species of Curcuma and Zingiber (Fig. 1). Tuberous and feeder roots are produced from the rhizome. The tuberous roots are fleshy, each forming a swollen tuber at or near the apex later in the growing season.
Hemiorchis produces elongated, creeping, fleshy rhizomes, but no root tubers have been observed. In cultivated plants, the slender connections between the perennating sections of rhizome break during the dry season and each disconnected section produces one or more buds, which grow into leafy shoots (Fig. 2).
Pseudostems. The laminae in both genera are decurrent onto the petiole. The ligule is a very short membranous structure at the junction of the leaf sheath and the petiole.
In Hemiorchis, the pseudostem shape, petiole morphology (length and shape), lamina shape and indumentum presence allow differentiation of the species. In Gagnepainia, there is little variation in vegetative structure between the species but there are some subtle characters by which they can be distinguished, namely the clasping of the basal leaf sheaths, the channelling of the petiole, the degree of folding of the plicate leaves, and the presence of an indumentum on the abaxial leaf surface. Indumentum. An indumentum of simple hairs occurs on various parts of the pseudostems. Its presence and coverage vary and can occasionally be of taxonomic importance.
Inflorescences. Both Gagnepainia and Hemiorchis flower precociously at the beginning of the rainy season before any vegetative growth occurs, although in cultivated plants flowering may also occur after vegetative shoot growth has begun. The leafless inflorescence in both genera is a spike with sessile flowers borne spirally along an unbranched rachis. It arises directly from the rhizomes and the peduncle is covered initially by a few inflorescence sheaths exposing only the rachis. One to a few flowers open per day and last for only about a day. An indumentum is present on most parts of the inflorescence including the sheaths.  Kurz (1873) and King (1894) recorded bracts in Hemiorchis burmanica and H. pantlingii, respectively. Baker (1890) reported membranous, deciduous bracts in Hemiorchis, and Larsen et al. (1998) stated that each flower was subtended by a caducous bract. Larsen & Triboun (2000) mentioned that the inflorescences were either bracteate or ebracteate, and Singh et al. (2012) said the flowers could be ebracteate or with bracts to c.1 mm long. Floral bracts were observed only in a single photograph from the Smithsonian Institution and on one specimen from Kew (K000649571) during this revision. They seem to occur rarely in Hemiorchis but never in Gagnepainia.
Flowers. The calyx of Hemiorchis is more or less infundibuliform with three equal or subequal teeth 1/4 to 1/3 the length of the calyx and shorter than that of Gagnepainia, which is tube-like with lobes 1/3 to 1/2 the length of the calyx.
In Gagnepainia (Fig. 3A,B) and Hemiorchis (Fig. 3C), the floral tube is slender and narrow, surrounded by the calyx tube. The apex of the floral tube opens into a chamber to which the remaining perianth parts are attached. This is the floral chamber, which has not been described in detail before. We hypothesise that the floral chamber serves as a collection area for nectar, which in both genera is produced from a pair of epigynous nectaries at the base of the floral tube.
The staminodes in both genera are petaloid and are attached at the same level as the labellum and laterally to it. At the base of each staminode is a gland-like appendage that is situated at the sides of the opening to the floral chamber. In Hemiorchis, these appendages are more or less triangular and flap-like, whereas those of Gagnepainia are larger and more pronounced.
The corolla lobes of Gagnepainia reflex distinctively at anthesis, whereas those of Hemiorchis are generally flat with involute margins. The labellum in Hemiorchis is shallowly dish-like or deeply cymbiform with a mid-region of one or two keels that end as apical projections of the labellum. In Gagnepainia, the labellum is a more complex structure with two wing-like side lobes, a channelled mid-region and the apex adorned with 5 or 3 distinct projections.
In Hemiorchis, the androecium is made up of a short and slightly curved filament bearing the more or less rectangular anther, which has a shortly recurved apex. The androecium of Gagnepainia is made up of a long and arching filament connecting the lanceoloid anther with a more or less tapering apex.
The ovary in both genera is more or less ovoid to oblong, larger on the lower flowers, smaller and globose on the upper ones. It is densely puberulous with longitudinal grooves that become obvious as the ovary develops, and parietal placentation.
Fruits. The fruits of both genera are thick-walled capsules that are variously grooved and shortly puberulous. The calyx is persistent at the apex of the capsules, and the remaining perianth parts may be present as shrivelled remnants. There are preliminary indications that the direction of dehiscence differs between the two genera, but there is not sufficient evidence at present to allow a definite conclusion. Results obtained in the 2013 growing season seemed to show that in Hemiorchis the capsules dehisced apically, the pericarp splitting into three valves from apex to base. Some seeds remained attached to the valves while others fell. The valves were brittle and also soon fell. By contrast, in Gagnepainia dehiscence seemed to occur basally, the capsule splitting into three valves from base to apex and remaining weakly connate as a united, brittle pericarp. The split pericarp soon fell, leaving the seeds attached to the three placentae that remained on the inflorescence. Hand pollinations carried out in 2019 did not result in ripe fruits, so it is not yet possible to be confident that this is a useful character to separate the genera.
Thirteen seeds in a capsule of Gagnepainia harmandii (RBGE 19991163A) was the highest number recorded, of nine capsules obtained by hand pollination of three Gagnepainia accessions (RBGE 19991163A, 3 capsules; 20010444A, 3 capsules; 19871253A, 3 capsules) and three capsules from one Hemiorchis accession (RBGE 19991652A). The small, smooth seeds of both genera are obovoid to globose, light to dark olive-green in colour, and each with a short neck at the base that attaches to the placenta. Each seed is covered by 1/3 to 1/2 from the base by a white, veil-like aril.

Molecular phylogeny
The results of our phylogenetic analysis (Fig. 4) show that Gagnepainia and Hemiorchis are sister taxa that form a clade with 100% support in both Bayesian and ML analyses. Individually, Gagnepainia and Hemiorchis are monophyletic, each with 98-100% support in both analyses. These results confirm those of Williams et al. (2004) but with improved statistical support. Within the Gagnepainia clade, the two samples of Gagnepainia godefroyi form a strongly supported clade.
When rooted with Alpinia, the Gagnepainia-Hemiorchis clade clusters with the Globba clade to make the tribe Globbeae (Kress et al., 2002), but the support for this clustering is quite low (38% posterior probability in Bayesian analysis, 38% ML bootstrap). Only adding more sequence data in a future study can prove or disprove the monophyly of this tribe.

S Y S T E M A T I C T R E A T M E N T
Key to the genera of Globbeae 1a. Rhizome with finger-like tuberous roots; lamina not decurrent onto petiole; inflorescence a thyrse with cincinnate branches, terminal on pseudostem, rarely on a separate leafless shoot and then composed of cincinni; bracts showy and overlapping or greatly reduced to absent; floral tube conspicuously reflexed; labellum fused to floral tube, bifid or bilobed, rarely emarginate, lacking central point or lobe; filament long and arching, anther basifixed, hinged at junction with filament, with lateral appendages (except subg. Mantisia); fruit usually globose and rugose (elongate, ridged in sect. Nudae) _______________________________________________________ Globba 1b. Rhizome either long, irregular, without tuberous roots or tubers, or short and regular with tuberous roots bearing swollen tubers towards tips; lamina decurrent onto petiole; inflorescence spicate, cincinnate branches lacking, borne on a leafless stem; bracts absent or, if present, curved, subulate; floral tube straight; labellum free from floral tube, with a narrow central point or lobe; anther basifixed, not flexing at junction with filament, without lateral appendages; fruit ovoid-elliptic with numerous longitudinal ridges _____________________________________________________________ 2 2a. Rhizome short, with numerous tuberous roots and tubers towards tips; individual plant generally of multiple pseudostems; flowers generally white with light yellowish orange to orange or green with light yellowish green, lacking red or reddish brown colouring; corolla lobes tightly rolled up at anthesis, margins not involute; labellum fishtailshaped or semilunar with two flat side lobes and a channelled mid-region ending in 5 or 3 distinct apical projections; filament long in proportion to flower, much longer than labellum; tip of anther acute; fruit a thick-walled capsule, more or less elongate or ovoid __________________________________________________ 1. Gagnepainia 2b. Rhizome long, creeping, brittle, without tuberous roots and tubers; individual plant generally of single pseudostems; flowers mostly light creamy brown to brownish pink (with or without pink, light yellow or orangey yellow); corolla lobes flat, reflexed, never coiled at anthesis, margins more or less involute; labellum deeply cymbiform with central ridge(s) and apical projection; filament short in proportion to flower, Flowers: basal ones arranged in a spiral and subsequently in whorls or spirally arranged, sessile, zygomorphic, opening successively. Calyx tubular, 3-lobed, divided up to 1/2 of calyx tube length, pale whitish green or light green, finely puberulous, persistent in fruit.
Floral tube straight and slender, as long as or longer than calyx tube, off-white to light greenish yellow or light green. Floral tube chamber infundibuliform, attached directly from the base to floral tube, off-white to light green. Corolla oblong, dorsal lobe larger than or equal to lateral lobes, tip obtuse, rolled up when flowers open, light yellowish or light green, adaxial shortly puberulous, abaxial glabrous. Lateral staminodes petaloid and winglike, obliquely obovate, flat or reflexed with a thickened upper margin and protruding appendage present at the base, white with light yellowish orange to orange and an olivegreen to yellowish brown spot on each basal appendage or light yellowish green to green and glistening white basal appendage. Labellum a complex structure, fishtail-like or semilunar shape with two flat side lobes and a channelled mid-region ending in 5 or 3 distinct apical projections, side lobes are more or less squarish with two rounded angles at the margin or are almost semicircular with recurved apical margin, mid-region an open channel leading down to floral chamber with no basal appendage, bordered on each side by a raised keel adjoining the side lobes, apex of labellum comprising 5 (2 vertical : 3 horizontal) or 3 (2 vertical : 1 horizontal) distinct projections, most of labellum white to offwhite with bright yellowish orange to orange apex or side lobes light yellowish green to green with mid-region and apex glistening white. Stamens long, arching and glabrous, filament longer than anther, anther largely lanceoloid with more or less tapering apex, thecae narrowly lanceolate tapering at both ends and exserted, pollen yellow. Ovary elliptic or oblong to globose, pale to light green, longitudinal grooves unclear or up to c.8 and densely puberulous, tricarpellate, unilocular, placentation parietal; epigynous glands 2, subulate; style single, filiform; stigma clavate to globose, exserted from apex of anther between thecae. Fruit a thick-walled capsule, more or less elongate or ovoid to oblongovoid and slightly flattened, appearing almost bifacial, with persistent calyx and remaining perianth shrivelled, pale to light green, finely puberulous, dehiscing into three valves. Seeds obovoid to globose, attached to placentae by a short neck, light green to light olive green and smooth. Aril translucent white, veil-like and covering 1/3 to 1/2 of seed.
Distribution. Two species occurring in Thailand, Laos and Cambodia. Perhaps also in Vietnam.
Ecology. Typically growing in partly shaded to shady understorey of bamboo, hardwood, deciduous or mixed evergreen forest, often growing along streams and seasonal streams, and in association with granite, shale or limestone substrate, 60-1000 m altitude. Occasionally remaining in disturbed, fire-damaged or degraded vegetation.
Key to the species of Gagnepainia 1a. Petiole open with more or less undulate wings; leaves 5-11, strongly plicate, abaxial surface more or less puberulous; flowers mostly white with light yellowish orange to orange; labellum fishtail-shaped, side lobes more or less square with two rounded angles at margin, labellum apex with 5 (2 vertical : 3 horizontal) projections ____________________________________________ 1.1. G. godefroyi 1b. Petiole more or less narrowly channelled, wings not undulate; leaves 3-7, weakly plicate, abaxial surface glabrous; flowers mostly green with light yellowish green; labellum semilunar, side lobes almost semicircular with recurved apical margin, labellum apex with 3 ( Plants to 70 cm tall; basal leaf sheaths 2-4, alternate, margins not overlapping, open and tightly clasping, apex shortly tapering, pale to light green, paler or white at base, shortly puberulous, denser and longer on margin. Petiole 4-9.5 cm long, upper ones longer, openly channelled with more or less undulating wings. Ligule puberulous, translucent to tinged with faint brown. Leaves 5-11, strongly plicate, 10-39 × 6-13 cm, adaxially light green to green, whitish hirsute in 2 rows along secondary veins, more or less sparsely puberulous on lamina, denser along veins parallel to the margin, abaxially light greyish to silvery green, more or less puberulous to puberulous. Basal inflorescence sheaths 2-6, alternate, overlapping but not fused, apex shortly tapering, light green, basally paler, puberulous. Inflorescence 7.5-38.5 cm long, pale to light green, puberulous. Flowers: basal ones arranged in a spiral and subsequently in whorls, each whorl comprising a compact spiral of up to 5 flowers. Calyx 0.9-1.7 × 0.2-0.3 cm, divided up to 1/2 of calyx tube length, apex more or less obtuse, off-white to pale whitish green, puberulous. Distribution. Laos and Thailand (Fig. 6).
Habitat and ecology. 230-1000 m altitude. Gagnepainia godefroyi is a distinctive species that appears to be the more common and widespread of the two species of this genus. It is characterised by its small, white flowers with light yellowish orange to orange markings, fishtail-shaped labellum with two flat lateral lobes that are rather square with two rounded angles at the margin, the mid-region of the labellum being an open channel leading to the floral chamber, and the apex of the labellum adorned by 5 (2 vertical and 3 horizontal) distinct projections that are white (the 2 vertical ones) and bright yellowish orange to orange (the 3 horizontal ones). When in bloom, it can easily be distinguished from the other species, Gagnepainia harmandii, which has mostly green flowers and different floral stuctures. The two species may be confused when not in bloom, because they are similar in vegetative morphology, requiring closer examination to tell them apart. Vegetatively, Gagnepainia godefroyi differs from G. harmandii by having tightly clasping basal leaf sheaths, openly channelled petioles with undulating wings, and strongly plicate leaves with puberulous abaxial surfaces making them more or less velvety to touch. By contrast, Gagnepainia harmandii has basal leaf sheaths that are up to half or apically free from the pseudostem, narrowly channelled petioles without undulating wings, and weakly plicate leaves that are glabrous on the abaxial surfaces and more or less leathery to touch. By these characters, it is possible to tell the two species apart even when they are not in bloom.
Baillon, in the protologue (Baillon, 1895), stated that he had abundant material of one species, which came, he said, from the "Montagne de Lakhon". This is all the locality information to be found in the protologue. When Schumann (1904) made the combination in Gagnepainia, he repeated this information although with a misspelling in the place name, as follows, "Berge bei La-Khou (Godefroy in Expedition Harmand)". On examination of the material at P, we found four sheets which match the protologue. There seems little doubt that the material on these sheets was collected by Godefroy, but the evidence that they form a single gathering (Turland et al., 2018; Art. 8) is weak. Sheets 1, 3 and 4 all state that the material was collected in Cambodia, but Lakhon is, in fact, the old name for the town of Nakhon Phanom, Thailand, and for the lands around it, on both sides of the River Mekong. A map in Harmand (1994, pp. 114-115) shows the "Province de La-Khon" stretching across the River Mekong. There are no mountains in Nakhon Phanom of Thailand (although the name means 'Hill City'), but there are limestone mountains on the Laotian side of the river in the provincial capital of Khammouane, Tha Khèk. It seems likely that Godefroy collected his material in Khammouane Province of Laos rather than Nakhon Phanom Province of Thailand.
The sheet with barcode number P032684 clearly bears the name 'Hemiorchis godefroyi' in Baillon's hand and shows the characters of the species in flower. It is the most suitable of the original materials to serve as lectotype. Sheets 2, 3 and 4 described above cannot be shown conclusively to form part of a single gathering with the lectotype, so they remain syntypes.
It should be noted that two Plants to 60 cm tall; basal leaf sheaths 2-5, alternate, margins not overlapping, open and up to half or apically free from pseudostem, apex shortly tapering, pale to light greyish green, paler or white at base, glabrous to shortly puberulous, whitish hirsute on margin. Petiole 5.5-12 cm long, upper ones longer, more or less narrowly channelled, wings not undulate.
Proposed IUCN status. Least Concern (LC). AOO = 32 km 2 , EOO = 187,651 km 2 . This taxon appears to be less common than Gagnepainia godefroyi, but most of the collections have been made near or within protected areas. Gagnepainia harmandii is a distinct species with a more southerly distribution than G. godefroyi. Although Gagnepainia harmandii is similar in its vegetative morphology to G. godefroyi, there are vegetative characters that allow the two taxa to be distinguished from each other, as described above. Gagnepainia harmandii in bloom can hardly be confused with G. godefroyi, because it is characterised by flowers that are predominantly green and yellowish green, its labellum is half-moon-shaped with two flat side lobes that are almost semicircular with a recurved apical margin, the apex of the labellum is adorned with 3 distinct projections that are a glistening white colour, 2 vertical and 1 horizontal.
Only a single sheet of the type collection of Hemiorchis harmandii has been located during this study. Recognising that duplicates may yet be found in other herbaria, we designate this sheet at P, barcode P0032686, as the lectotype.
In 1895, when Baillon described Hemiorchis godefroyi and H. harmandii there was also a third species, H. thoreliana. Baillon was uncertain whether Hemiorchis thoreliana was a good species or merely a variety of H. harmandii but he proceeded to name it provisionally as a separate species.
Two specimens of Hemiorchis thoreliana have been found during this revision. One is Thorel s.n. (P032687) from Cochinchine, and the other is Harmand 1895 (P06136205) from an unknown collection locality. Thorel's collection is labelled 'Hemiorchis thoreliana' in Baillon's handwriting and is marked as the type of this name, although it is impossible to be sure whether this was done in Baillon's time. Harmand 1895 is labelled 'Crescit in montibus Lakoon, 9/1877'. A second label, in Gagnepain's handwriting states, 'Confusion d'étiquettes. M. Pierre attribue à cette plante la localité du Gagnepainia godefroyi', i.e. mixed labels. Mr Pierre attributes the locality of Gagnepainia godefroyi to this plant. Of these two collections, only Thorel's was definitely seen by Baillon so we choose it here as the lectotype of Hemiorchis thoreliana.
Close examination of these specimens and comparison to Gagnepainia harmandii revealed no differences. Furthermore, an annotated illustration of a flower by Baillon attached to the holotype of Hemiorchis thoreliana clearly shows a flower bearing a labellum with two flat side lobes that are almost semicircular and, most significantly, the labellum apex is detailed with 3 (2 vertical : 1 horizontal) distinct projections. Considering all the available evidence, Hemiorchis thoreliana is placed in synonymy in this revision. There are no grounds to maintain it as a distinct species.
Baillon's protologue (1895) is very unclear where the types of Gagnepainia harmandii and G. thoreliana were collected. Of the latter, he said nothing at all, and of the former he said simply that it was probably a Cambodian plant. The label of the type of Gagnepainia harmandii states in Baillon's handwriting that it came from Cambodia. The label of the type of Gagnepainia thoreliana states only 'Cochinchine', which may refer to southern Vietnam but was also used until at least the 1940s to include Cambodia (see, for example, Gagnepain, 1944, p. 41, in which Godefroy is said to have accompanied Harmand 'au Cambodge, en Cochinchine, où il récolta 882 échantillons reçus en 1876-8'). Thorel collected the type of Hemiorchis thoreliana during a long expedition along the River Mekong, which began in Saigon and passed through the Cambodian towns of Phnom Penh, Oudong, Siem Reap, Kratié and Stung Treng before crossing into Lao and Thai territories (Gagnepain, 1911). We have not been able to determine the collection localities of Thorel's collection along this route, nor have we seen more recent collections of this species from Cambodia. In preparing Figure 6, we have placed the type of Gagnepainia harmandii in the centre of Cambodia and that of G. thoreliana in An Giang Province of Vietnam, very near the Cambodian border, because this is the best information we have. It should be noted, however, that no material of Gagnepainia has ever been seen by Trần Hữu Đăng, one of the best Zingiberaceae collectors working in Vietnam (Trần Hữu Đăng, Bình Dương, personal communication, June 2017). Deciduous and precocious understorey herbs to 85 cm tall, erect, individual plant of isolated pseudostems forming loose to dense spreading clumps. Rhizomes long, creeping and irregularly shaped, forming along the length of the rhizomatous roots, light brown. Rhizomatous roots creeping and fleshy, white when young, turning light brown with age.

Hemiorchis
Feeder roots fine and numerous, white when young, turning light to dark brown with age.
Pseudostems arising with plane of distichy of leaves parallel to rhizome, broad and almost flattened to rounded, with 2-6 basal leaf sheaths, pale to light green, with or without flush of maroon or light brownish pink, longitudinal venation distinct, puberulous, indumentum present along sheath margins. Petioles short to long with lamina decurrent, openly or narrowly channelled. Ligule perpendicularly encircling the inner circumference of the base of each petiole, very short and membranous, puberulous, almost translucent to tinged with a light reddish brown. Leaves 3-9 on each pseudostem, alternate, lanceolate, broadly lanceolate to slightly ovate, plicate, adaxially light to dark green, indumentum present along leaf venation, abaxially a contrasting light greyish to silvery green with or without flush of light maroon, puberulous or glabrous, base obtuse to rounded, apex acuminate or attenuate. Basal inflorescence sheaths 2-6, finely puberulous, pale to light green, with or without flush of maroon or pale to light reddish brown with or without fine maroon specks, longitudinal venation distinct. Inflorescence a spike to 26.5 cm tall, erect, pale to light green or off-white to pale light brown, with or without fine maroon specks, darker at peduncle and lighter at rachis, finely puberulous. Floral bracts absent or, if present, curved, subulate, each subtending one flower. Flowers spirally arranged, sessile, zygomorphic, opening successively. Calyx infundibuliform, 3-lobed, divided up to 1/3 of calyx tube length, light green to light reddish brown with or without fine maroon specks on lobes, finely puberulous, persistent in fruit. Floral tube straight and slender, shorter than, or as long as to twice as long as calyx tube, off-white to light greenish yellow. Floral tube chamber cupuliform, dorsiventrally attached from base to floral tube, off-white to light pale yellow. Corolla lobes oblong to broadly oblong, dorsal lobe larger than or equal to lateral lobes, margins involute, pale to light creamy brown or light brownish pink, adaxially shortly puberulous, apex connate forming an acuminate tip. Lateral staminodes petaloid, paddle-shaped, obovate or shallowly concave, light creamy brown to brownish pink with or without pink or light yellow to orangey yellow, basal appendage flap-like, more or less triangular, light to dark brownish red or light to dark yellow with or without red markings.
Labellum shallowly dish-like or deeply cymbiform, mid-region distinctly raised with a single broad keel or a double keel more or less channelled between, running the length of labellum from base to apex, with an appendage at base and a projection at apex, side lobes concave, adjoining both sides of labellum, variably coloured light yellowish brown, pinkish brown, maroon and yellow to orange. Stamen: short, slightly arching and glabrous, filament short, shorter than or equal to anthers; anthers more or less rectangular with slightly recurved apex, thecae linear and exserted, pollen white to off-white. Ovary oblong to globose, light pale green to light yellowish brown, up to 10 longitudinal grooves present and densely puberulous, tricarpellate, unilocular, placentation parietal; epigynous nectaries 2, subulate; style filiform; stigma clavate to globose, exserted from apex of anther between thecae. Fruit a thick-walled capsule, more or less ellipsoid, with persistent calyx and remaining perianth shrivelled, light green to green or light creamy brown, with or without maroon specks, up to 10 longitudinal grooves and finely puberulous, dehiscing into three valves. Seeds obovoid to globose, attached to placentae by a short neck, light olive to brownish green and smooth. Aril translucent white, veil-like and only covering the neck or up to 1/3 of the seed.
Distribution. Three species ranging from eastern Nepal, southeastwards through northeastern India (West Bengal, Meghalaya, Assam, Mizoram), Bangladesh, Burma and northern Thailand. We have not seen material which is definitely from Sikkim or Bhutan though parts of the south of Sikkim are at suitable altitude.
Ecology. Typically growing in partly shaded to shady understorey of bamboo, Dipterocarpus and mixed deciduous forest, and occasionally growing in association with limestone substrate.
Hemiorchis can be recognised by its orchid-like flowers, which are sessile with a densely puberulous ovary surmounted by an infundibuliform 3-lobed calyx, and a slender floral tube with a distinct, cupuliform floral chamber bearing the remaining orchid-like perianth. The three corolla lobes are generally flat with involute margins, and the petaloid staminodes are paddle-shaped, obovate or shallowly concave. The stout stamen comprises a short filament with rectangular anther, protruding from above the basal appendage of the labellum. The labellum is shallowly dish-like or deeply cymbiform and the mid-region distinctly raised with a single broad keel or a double keel more or less channelled between; this runs the length of the labellum from the base to the apex with an appendage at the base and a projection at the apex. The thick-walled capsules are usually formed by the basal flowers, occasionally by the apical ones. They are more or less ellipsoid with persistent calyx and are distinctly grooved and finely puberulous. Determination of specimens from images is more difficult in Hemiorchis than in Gagnepainia. We cannot determine the specimens at CAL, which we have seen only as images. For this reason, we are not confident of the distributions of the species in India.
Key to the species of Hemiorchis 1a. Petiole > 4 cm, long, slender and narrowly channelled; leaves 3-6, elliptic to slightly ovate; staminodes with light to dark brownish red basal appendage; mid-region of labellum a single broad keel, apical projection a single to weakly bilobed or triangular to tridentate lobe ______________________________________ 2. Plants to 60 cm tall, pseudostems more or less rounded; basal leaf sheaths 4-6, alternate, margins not overlapping and open, apex shortly tapering, pale to light green, with or without flush of maroon, whitish hirsute on margin only to puberulous. Petiole 4-11.5 cm long, upper ones longer, slender and narrowly channelled. Ligule shortly puberulous, translucent to tinged with light reddish brown. Leaves 3-6, elliptic to slightly ovate, 6.5-23 × 4-8 cm, adaxially light green to green, whitish hirsute in 2 rows along secondary veins, denser along veins parallel to margin, abaxially light greyish to silvery green, glabrous or puberulous, base more or less obtuse to rounded or weakly, asymmetrically rounded, apex shortly acuminate to acuminate, margin entire. Basal inflorescence sheaths 2-5, alternate, margins overlapping but not fused, apex shortly tapering, pale to light green, with or without flush of maroon, basally paler, puberulous. Distribution. Burma and Thailand (Fig. 8). Distribution. India, Nepal (see Fig. 8).

Etymology.
Greek, red rachis. In the protologue, Schumann (1904: 128) cited a single collection as follows, "In den Khasia-Bergen, lebend eingesandt nach Kew von Gustav Mann, blühte dort." Additionally, he referred to Hemiorchis burmanica sensu Baker in Curtis's Botanical Magazine (1890: t. 7120) and in the Flora of British India (1890: 207). The original material of Hemiorchis rhodorrhachis thus comprises a herbarium collection made from a plant cultivated at Kew and a painting in Curtis's Bot. Mag. Three sheets were found in a type cover at K, Anon s.n. (K000640564), Mann, G. s.n. (K000640565) and Mann, G. s.n. (K000640566). Each was collected on a different date, so they are not parts of a single gathering. The sheet with barcode K000640564 bears an annotation reading, "Type specimen of Bot. Mag. t. 7120". We regard this and the painting in Curtis's Bot. Mag. as original material. Of the specimen and the painting, we select the specimen as the lectotype of Hemiorchis rhodorrhachis. It is uncertain whether specimens K000640565 and K000640566 are part of the original material. If they are, they are syntypes, not isolectotypes.