Hedychium hookeri C.B. Clarke ex Baker (1892: 230)

Bai, Lin, Hu, Xiu, He, Jianghai & Tian, Zhongcheng, 2021, New records of Hedychium hookeri (Zingiberaceae) from China and Myanmar, Phytotaxa 494 (2), pp. 237-243 : 238-242

Hedychium hookeri C.B. Clarke ex Baker (1892: 230) . ( Figure 1 )

Lectotype (designated here):— INDIA. Meghalaya State: Khasia Hills [Khasi Hills], Kala Pauce , 27 June 1850, J.D. Hooker & T. Thomson 1350 ( K barcode K000640478 ! ; isolectotype: K barcode K000640479 !).

Perennial rhizomatous herb, 40–80 cm tall. Rhizome fleshy, 1.4–1.7 cm in diameter, externally brownish white, internally white, turning pale purple close to aerial stem; root fleshy, 4–6 mm in diameter; leafy shoots slightly bending or arching, often glaucous, with 4–8 well-developed laminae when in flower; aerial stem 12–20 mm in diameter at base, 6–9 mm in diameter at centre; leaf sheaths green, green or slightly pale burgundy tinged towards margins and or pure burgundy; ligule almost entire, only slightly emarginate at apex, 14–22 mm long, membranous, often semihyaline with pale burgundy colour or pale pink, rarely hyaline; petiole 5–25 mm long, shorter in upper leaves, pale green, pink or burgundy; laminae oblong-elliptic or ovate (length: width ratio 1.8–3.7), 13–29 × 5–13 cm, base subcordate to rounded to obtuse, rarely cuneate (at uppermost leaves), apex acuminate to caudate, adaxially green except the mid vein sometimes being burgundy, lateral veins raised, abaxially dark burgundy or pale green and more or less tinged burgundy, glabrous on both sides. Inflorescences terminal; peduncles 3–10 cm long, spikes oblong, 4–10 × 1.5–2.5 cm, basal one to three bracts sterile, the basal-most one up to 2.5–7 cm long, enclosing spike axis, green or often brownish green; fertile bracts 8–14, each subtending one flower, narrowly ovate to ovate, 8–15 mm long, 7–10 mm wide when flattened, green but often tinged red, their margins strongly incurved, apex acute to rounded; bracteoles 3–6 mm long, pink and semi-hyaline; flower 2–3.3 cm long; calyx 7–9 mm long, membranous, pale pink; floral tube 1.1–1.3 cm long, ca 2.5 mm in diameter, pale pink; corolla lobes subequal, narrowly oblong to linear, 10–12 mm long, margins strongly incurved, ca 2 mm wide when flattened, pink; labellum obcordate to spathulate, 6–9 × 5–6 mm, cream yellow, glabrous on both sides, lower part folded and embracing the filament, claw 4–5 mm long, apex emarginate or bilobed; lateral staminodes narrowly obovate to spathulate, 9–12 × 3–5 mm, cream yellow, glabrous on both sides; stamen 1.4–2 cm long; filament 1.0– 1.3 cm long, often strongly arching and bending down towards labellum, white to pale pink; anther 4–7 mm long, bright yellow; connective tissue pale yellow; style lying in a groove in the floral tube and held between thecae of stamen, pale yellow but often tinged red, stigma extends to the apex of anther thecae, thicker than style, infundibuliform, 1–1.5 mm long, ca. 1.5 mm in diam., pale yellow, ostiole ciliate, ovary obovoid, ca. 2 mm in diameter, glabrous; epigynous glands two, bluntly conical, 1.5–2.0 mm long. Fruits compressed obovoid or oblate, strongly bluntly trigonous, 1.0–1.2 × ca 1 cm, pale orange externally, dehiscing by three valves when mature, inner surface of the pericarp shiny orange to scarlet; within each cell seeds aggregated into an oblong seed mass, ca. 6 × 5 mm; seeds narrowly obovoid, slightly angled at one side, 2.5–4 × 1.2–2 mm, black, shiny; aril entire, almost enveloping the whole seed, dark bluish black, juicy.

Typification:— In the protologue, Baker (1892) cited collections of J.D. Hooker & T. Thomson from Khasia Hills and collections of W Griffith from Assam. J.D. Hooker’s plant collections are mainly deposited at K, with some at MANCH and W Griffith’s specimens are now mainly deposited at K, with some duplicates at BR and CAL ( Stafleu & Cowan 1976 –1988). A search at BM, BR, E, MANCH and K revealed three specimens collected by J.D. Hooker and T. Thomson (two sheets at K and one at BM) and one specimen collected by Griffith (BM). The specimen at BM (barcode 000574549) has a small label annotated Khasya Griffith. Khasya and Kashia (or Kassia or Khasiya) are spelling variants ( Styles & Burley 1972). This mountainous region is now called the Khasi Hills and belongs to Meghalaya State, while before 1972 (including Griffith’s time), it was part of Assam State, which explains why Baker (1892) recorded Griffith’s specimen as collected in Assam. All four specimens represent original materials of the name. We here select one of Hooker and Thomson’s specimen at K (barcode K000640478) as the lectotype because it is the best preserved flowering specimen and it also has a determinavit slip of C.B. Clarke determining the species as Hedychium hookeri sp. nov., a field label with diagnostic description “leaves below, stems glaucous whitish, Fl. palish yellow”, the locality and date of collection “Kala Pauce, June 27/50”, and a sketch showing a single flower. The other specimen at K (barcode K000640479) with the same collection number is an isolectotype, while the specimen of J.D. Hooker and T. Thomson at BM without collection number and the specimen of Griffith at BM remain syntypes.

It is noted here that our collections from China fit well with the two characters mentioned in the field note on the lectotype. The character of lower side of leaves and stems being glaucous is not mentioned in the protologue but is observed in two populations in China (one in Honghe and the other cultivated in Kunming Botanic Garden, although the population in Nujiang seems not glaucous). Also, the labellum and lateral staminodes of the species are indeed palish yellow in the population from Lüchun and the plant cultivated in Kunming Botanic Garden, not sulphur yellow as described in protologue.

Specimens examined:— CHINA. Yunnan, Lüchun, Huanglianshan National Nature Reserve , elev. 1970 m, 22.896° N, 102.303° E, 1970 m, 23 June 2017, Y.Q. Wu 1 ( IBSC); ibidem, Y.Q. Wu 2, Y.Q. Wu 3 ( IBSC) ; Yunnan, Nujiang, Lushui, Pianma , elev. 2075 m, 26.049° N, 98.615° E, 5 August 2020, X. Hu 295 ( IBSC); ibidem, X. Hu 296, X. Hu 297 ( IBSC) ; INDIA. Assam State [now Nagaland], Naga Hill , elev. 5900 ft, 26 June 1935, N.L. Bor 4480 ( K) . MYANMAR. Kachin State. North, upper Burma , elev. 5000 ft, 14 May 1914, F. Kingdon-Ward 1550 ( E); Myitkyina District, Laugyang-Pyetpah , elev. 5400 ft, 25 May 1929, Sukoe 9990 ( E); Hpimaw Valley , elev. 5000 ft., 7 June 1919, R. Farrer 1007 ( E) .

Distribution:— Hedychium hookeri is now known in Yunnan Province, China, north-eastern India and northern Myanmar.

Ecology and phenology:— Hedychium hookeri grows on rocks or trees under forest, at elevations of about 1600– 2100 m. Flowering starts in early May and lasts till late June. Fruits begin to form in early June, and mature from late June.

Notes:— Hedychium hookeri can be easily recognized by a combination of petiolate leaves and oblong-elliptic or ovate lamina, longish ligules, short spikes with few bracts in number and an arching stamen by which its flower resembles some species of Globba Linnaeus (1771: 143) . The Chinese records fit well with the protologue and type specimen, except that the bracts were described as green in the protologue, but are often green tinged red in all three populations that we have observed in China.

During our literature research, we have noticed that Hedychium longipedunculatum , a species that was also described based on plants around the China-India border in Xizang, China is very similar to H. hookeri , except for the colour of the arils, although Sastry & Verma (1968) did not realize the similarity and only compared H. longipedunculatum to H. densiflorum . The colour of arils of H. longipedunculatum was described as bright red in the protologue. Moaakum & Dey (2013), who rediscovered this species in in eastern Indian ( Nagaland States ), did not describe the colour of the arils. The colour of arils of H. hookeri was not described in the protologue, but they are clearly dark black on the isolectotype specimen. In our experience of preparing specimens of Hedychium species from China, red arils turn pale yellow and semi-hyaline instead of black in dried herbarium specimens. We would therefore expect that the arils of H. hookeri to be a dark colour in fresh. Sanoj (2011), who rediscovered H. hookeri from China-India Border , also described the arils as black. Both populations (one from Lüchun , south-eastern Yunnan and one from Lushui , north-western Yunnan) with fruits we observed in China also have black arils. So far, black arils have not been recorded for any other species of Hedychium . Since we have not been able to assess the variation of this character in a larger sample and have not been able to examine any type specimen of H. longipedunculatum either, a treatment of H. longipedunculatum will be deferred, although we are of the opinion that the two most likely represent the same species.

Hedychium hookeri is also similar to another two high elevation species, namely H. densiflorum and H. putaoense . All three species occur in Pan-Himalayan region. They all have somewhat small flowers (2–3.9 cm long), one flower per bract and relatively small rhizome but rather thick fleshy roots, and leaf stems which go dormant in the dry season. Hedychium hookeri is further similar to H. densiflorum in the shape of its flowers. Both species have comparatively broad lateral staminodes compared to the labellum. Tanaka et al. (2016) recorded H. densiflorum from Myanmar but some specimens they cited represent H. hookeri , namely, F. Kingdon-Ward 1550 (E) and Sukoe 9990 (E, collector incorrectly cited as Sutuz). We have not been able to examine the remaining specimens cited so we cannot verify the existence of H. densiflorum in Myanmar, nor have we come across any other specimens of H. densiflorum in Myanmar. Hedychium densiflorum can be distinguished in herbarium specimens by its much longer and lanceolate lamina, the absence of a petiole and longer inflorescence with many more bracts (and flowers). When fresh, it can be identified by its attractive orange coloured flowers. Hedychium hookeri is further similar to H. putaoense in the size and general colour of the flowers, but H. putaoense can be easily distinguished by its lateral staminodes being much narrower than the labellum, much narrower and lanceolate lamina, shorter ligule, the absence of a petiole and densely villous calyx. A thorough comparison of the above mentioned four species including more subtle differences is given in Table 1 . Colour plates of H. densiflorum , H. longipedunculatum and H. putaoense may be consulted from Sanoj (2011: Plate 09. A–C, H), Moaakum & Dey (2013: Plate 1) and Ding et al. (2018: Figure 1 ).

The vegetative parts (especially the broadly ovate lamina and long petiole) of H. hookeri are extremely similar to H. ellipticum . The length of spikes is also somewhat similar. Hedychium ellipticum can, however, easily be distinguished in herbarium specimens by its spikes with compact and less convolute bracts, much larger flowers (11–13 cm long) and its filament being much longer than the labellum and lateral staminodes, and when fresh by its very different pure white labellum and lateral staminodes.

Figures

FIGURE 1. Hedychium hookeri A. Plant habit (fruiting). B. Infructescence (mature). C. Seed mass (showing bluish black arils enclosing entire seeds). D. Rhizome and roots dissection. E. Seeds with arils removed. F. Sub-mature capsules. G. Stem (showing petioles, ligules and lamina bases). H & I. Inflorescence. J. Flower dissection from left: two single flowers enclosed by bracts and bracteoles, flower with corolla lobes, labellum and lateral staminodes removed, three corolla lobes, labellum, two lateral staminodes. A, B, E are based on collection X. Hu 297, photographed by Xiu Hu; C, D, F–I are based on collection Y.Q. Wu 1, photographed by Yong Qing Wu.

Tables

TABLE 1. A comparison of Hedychium hookeri, H. longipedunculatum, H. densiflorum and H. putaoense (significant differences in bold).

Attributes	H. hookeri	H. longipedunculatum	H. densiflorum	H. putaoense
Data source	Three living collections from China	Protologue	Protologue, type specimen and living collections from China	Protologue and type specimen
Type locality	Meghalaya state, India	Xizang, China	Shivapuri, Nepal	Kachin State, Myanmar
Distribution	Eastern India, northern Myanmar, and southwestern China	China, north-eastern India	Nepal, eastern India and southwestern China	Northern Myanmar
Leafy shoot height	40–80 cm	20–40 cm	100–120 cm	20–50 cm
Ligule	14–22 mm long, apex emarginate	5–20 mm long, apex 2-lobed	10–12 mm long, apex obtuse	8–19 mm long, apex obtuse
Petiole length	5–25 mm	3–16 mm	0–10 mm	0–10 mm
Lamina size and shape	13–29 × 5–13 cm, oblong-elliptic or ovate	4–23 × 1.5–10 cm, elliptic or oblong-elliptic, base acute	12–35 × 3–10 cm, elliptic	13–23 × 3–7 cm, lanceolate
Lamina colour (abaxially)	More or less tinged burgundy	Light pinkish purple	Pale green	Pale green
Inflorescence length	4–10 cm	4–6 cm	10–18 cm	7–10 cm
Peduncle length	3–10 cm	5–14 cm	1–2 cm	7–10 cm
Fertile bract, colour and margin morphology	8–15 × 7–10 mm, green tinged with red, loosely convolute	Ca. 11 × 7 mm, green tinged with red, convolute	16–20 mm long, green, convolute	4–6 × 2.5–3 mm, purplish red, convolute
Bracteole length and colour	3–6 mm, pale red	Ca. 6 mm, red	8–10 mm, pale red on the base	2.0–2.5 mm, dark red
Calyx length and colour	7–9 mm, pale pink	11 mm, colour unknown	13–16 mm, light green	12–14 mm, pale red
Floral tube length and colour	1.1–1.3 cm, pale pink	Ca. 11 mm, colour unknown	16–20 mm, orange-red	10–13 mm, creamy yellow
Corolla lobes size and colour	1.0–1.2 × 2 mm, pink	Ca. 16 × 3 mm, light red brown dotted	11–13 × 3 mm, yellow	10–16 × 1–2 mm, red
Labellum shape, size and colour	Obcordate to spathulate, 6–9 × 5–6 mm, apex emarginate or bilobed, claw 4–5 mm long, cream yellow	Obcordate to spathulate, ca. 15 × 6 mm, apex deeply 2-lobed, claw 5 mm long, cream yellow	widely obovate, 8–10 × ca. 8 mm, sinus at apex 3.5–4 mm deep, not clawed, orange-red,	widely obovate, 12–14 × 4–7 mm, sinus at apex 2–3 mm deep, not clawed, orange
Lateral staminodes shape, size, and colour	Narrowly obovate to spathulate, 9–12 × 3–5 mm, cream yellow	Spathulate, 17 × 7 mm, creamy	Elliptic, 9–11 × 3–4 mm, orange-red	Broadly falcate to lanceolate, 11–13 × 3–4 mm, orange
Stamen length	1.4–2 cm	Ca. 2.2 cm	1.7–2.0 cm	1.4–1.7 cm
Filament length and colour	1.0–1.3 cm, yellow	Ca. 15 mm, yellow	1.0–1.2 mm, orange-red	11–12 mm, orange
Anther length and colour	4–7 mm, bright-yellow	Ca. 7 mm, bright-yellow	6.0–6.5 mm, orange-red	Ca. 5 mm, orange
Fruit size and indumentum	1.0–1.2 cm in diameter, glabrous	1.5 cm in diameter, hairy	1.5–1.8 cm in diameter, glabrous	0.5–0.7 cm in diameter, densely villous
Seeds size and colour	2.5–4 × 1.2–2 mm, black	3 × 1 mm, red	3–4 × 1.5–2.0 mm, red	3 × 2 mm, red
Aril	Juicy, entire, enveloping almost the entire seed; bluish black	Fleshy, shape unknown; bright red	Fleshy, divided into many separate strands; bright red	Fleshy, divided into many separate strands; bright red
Anthesis	May to June	May to July	July to August	May to July