Scientific name: Curcuma sahuynhensis Škorničk. & N.S.LýEnglish name: Vietnamese name: Nghệ sa huỳnhOther name:
Similar to Curcuma xanthella (subgenus Ecomata) in its elliptic-lanceolate, plicate laminae and L-shaped anther, but differs in the shape and size of the spike that appears above ground (6–15 × 5–9 cm; composed of 10–23 bracts with prominently reflexed apical halves arranged on an elongated rachis), overall smaller flowers (3.5–4.5 cm long), shorter (4 mm) and stouter anther spurs, longer anther thecae (6–7 mm long) and shorter epigynous glands (5–6 mm long) (versus spike 4–5 × 1.5–2 cm, composed of 4–8 bracts with a reduced rachis, basal part of spike often partly subterranean; flowers to 7.5 cm long, longer and more slender anther spurs (6 mm), shorter anther thecae (3–4 mm) and longer epigynous glands (ca 15 mm) in C. xanthella).
Type:—VIETNAM. Quảng Ngãi Province: Đức Phổ Dist., Phổ Thạnh commune, Đồng Vân Village, Núi Đồng Đế, Núi Đồng Vân, 14°39′28″N, 109°02′22″E, 183 m asl., 4 September 2010, Lý Ngọc Sâm, Phan Thế Cường, Lý-486 (holo SING (incl. spirit), iso E, P, VNM (incl. spirit))
Small rhizomatous herb to 0.8 m tall. Rhizome ovoid to narrowly ovoid, 1.5–4.0 × 0.5–1.0 cm, occasionally with a thin branch pointing downwards, light brown externally, creamy white to pale yellow internally, slightly aromatic, root tubers fusiform, 2–6 × 0.8–1.8 cm, light brown externally, pure white internally, buried deeply in the ground (distanced 8–15 cm from the main rhizome). Leafy shoots with ca 1–2 leaves at the time of flowering, with up to 10 leaves on mature plants past flowering; pseudostems 10–15(–20) cm long, green, composed of sheathing bracts and leaf sheaths; sheathing bracts 3–5, green, glabrous or sparsely puberulent, turning dry and papery with age; leaf sheaths green, glabrous; ligule up to 5 mm long, bilobed, hyaline, greenish white, translucent, glabrous, margin sparsely hairy; petiole 2–20(–24) cm long (petiole of first leaf shortest, innermost leaves longest), canaliculate, green, glabrous; lamina slightly unequal, ovate to elliptic, 20–38 × 9–16(–18) cm (measured in mature plants in late stage of flowering), plicate, adaxially bright green, glabrous, abaxially lighter green, glabrous but sparsely puberulous along midrib and near margin in apical part of lamina; midrib green, glabrous above, very sparsely puberulous below (hairs restricted to sides of midrib); base obtuse to rounded, slightly oblique; apex attenuate to acuminate, puberulent. Inflorescence lateral, arising at the same time as first 1–2 leaves; peduncle 6–16 cm long, to 8 mm in diameter, light green in parts exposed to light, sheathed by 3–5 leafless, light green, glabrous sheaths (turning dry and papery with age); spike to 6–15 cm long, 5–9 cm in diam. at the middle, with no obvious coma, composed of 10–23 bracts; bracts 3.0–5.5 × 1.5–4.0 cm, broadly to narrowly ovate to rhombic (broader at base, narrower at the apex), whitish to pale green at base with various degree of coral pink or red tinge, both sides glabrous, connate in lower 1/3–1/4, apices acute to narrowly acute, reflexed; cincinni with 3–5 flowers at the base of the inflorescence, 1–2 flower at the top; bracteoles subulate, 1–5 mm long, semi-translucent white, glabrous, often fully reduced. Flowers 3.5–5.5 cm long, exserted from bracts; calyx 14–19 mm long, 3-toothed, with unilateral incision, 5–8 mm, glabrous, semi-translucent white or with pink tinge; floral tube 1.8–2.8 cm long, narrowly cylindrical at base for ca 1.3–1.8 cm above the ovary, funnel-shaped at apex, externally white or with pink tinge, externally puberulous (less so in basal part), internally white, turning pale yellow towards apical part, densely hirsute at apical part, sparsely hirsute towards the base, with dorsally placed loose groove holding the style; dorsal corolla lobe 15–22 × 6–11 mm, triangularly ovate, concave, white or pale yellow with various degree of pink or red tinge, glabrous, apex mucronate, mucro ca 1 mm, sparsely puberulous; lateral corolla lobes 15–20 × 6–9 mm, triangular, apex broadly acute to obtuse, slightly concave, white or pale yellow with various degree of pink or red tinge, glabrous; labellum 15–23 × 12–18 mm, slightly obovate, with an incision 2–7 mm long, cream white at base, warm rich yellow at apex with bright yellow-orange band running through the centre; lateral staminodes 15–22 × 10–14 mm, unequally ovate to obovate to rhomboid, warm rich yellow, lighter towards base, covered with short glandular hair adaxially. Stamen 11–12 mm long; filament 4–5 mm long, cream-white to pale yellow, 3–4 mm broad at base, 2.0–2.5 mm broad at apex (the point of attachment to the connective), densely puberulent (glandular hair); anther L-shaped (angle ca 110°–120°), spurred, connective tissue pale yellow to pale yellow-orange, densely puberulent (glandular hair), anther spurs 3.5–5.0 mm long, stout, parallel with acute apices slightly divergent, creamy white to pale yellow, anther crest 0.3–1.0 mm long (almost negligible in some plants), apex emarginate, pale yellow; anther thecae 6–7 mm long, dehiscing along entire length, pollen white. Epigynous glands two, creamy yellow, 4–6 mm long, ca 0.6 mm in diameter, with blunt apices. Style white, glabrous; stigma capitate, ca 1 mm wide, creamy white; ostiole shortly ciliate facing forward. Ovary 3–5 × 2–4 mm, trilocular, creamy white, usually glabrous (rarely sparsely hairy at apical part). Fruit a globular trilocular capsule (with locules visibly bulging in ripe fruit), 11–15 mm in diameter, white, glabrous; seeds irregularly obovoid, 4–5 × 2–3 mm, light brown, shiny, enclosed in translucent white, laciniate aril. Ecology and phenology:—Growing in coastal lowland forests, on gravelly infertile soil in open spaces, shrubby vegetation as well as Acacia plantations. Curcuma sahuynhensis flowers from August to October and fruits from September to November. This flowering pattern corresponds with the beginning of the rainy season in central to northern Vietnam.
Etymology:—The specific epithet sahuynhensis is derived from Sa Huỳnh town, hometown of the second author, where this species was first collected. Sa Huỳnh area is well-known for its ancient rich culture dating to 1000 BC to 200 AD. Vernacular names and uses:—The species is locally called Rau Nghệ [Rau = vegetable, Nghệ = Turmeric (Curcuma)]. The name reflects the fact that C. sahuynhensis is often harvested as a local vegetable. Inflorescences and young leafy shoots are sold in the local market when in season and are used for preparation of boiled vegetable or soup (usually mixed with another wild vegetable: Lá Giang - Aganonerion polymorphum Pierre ex Spire (1905: 43), Apocynaceae).
Distribution and IUCN preliminary assessment:—Curcuma sahuynhensis is currently only known from Quảng Ngãi Province. During the field work conducted by the second author, many populations/subpopulations each consisting of 10–100 adult individuals were noticed growing naturally in open places or shrubby vegetation of the coastal lowland forests around Đồng Vân and Đồng Đèo villages. Its occurrence in the wild as well as in local vegetable markets have been also reported to us from Đức Phổ town. While the young shoots and inflorescences are harvested in the wild by local people as a seasonal vegetable, the rhizomes remain deep in the ground and regular harvesting does not seem to pose any threat to population sizes. While we have seen images from various sources of likely identical species from central Vietnam (without precise localities), we have also seen images of closely related, but likely distinct species from adjacent provinces. We therefore suggest treating this species as Least Concern (LC) until more comprehensive data on the extent of its occurrence and population sizes as well as relationships to other potentially distinct species will suggest the necessity for re-evaluation.
Additional specimens examined (paratypes):—VIETNAM. Quảng Ngãi Province: Đức Phổ Distict, Phổ Khánh commune, Diên Trường Village, Núi Đồng Đèo, 14°41’23.54”N, 109° 2’27.60”E, 95 m, 5 September 2010, Lý Ngọc Sâm, Phan Thế Cường, Lý-488 (SING, VNM).
Notes:—Curcuma sahuynhensis is fairly distinct from other species of subgenus Ecomata in Vietnam by its character combination of an L-shaped anther and an inflorescence composed of bracts arranged on an elongated rachis resulting in less overlapping bracts. The L-shaped anthers are not unusual in subgenus Ecomata and were observed in C. flaviflora Tong (1986: 37), C. newmanii, C. singularis Gagnepain (1907: 407) and C. xanthella, but all these species have spikes composed of few bracts arranged around a strongly reduced rachis, resulting in a fusiform to narrowly cupuliform shape of the inflorescence. Of the four species, C. xanthella has been selected for diagnostic purposes because of its plicate leaf blades, bright warm yellow flowers, and the fact that this species occurs in Vietnam, but mistaking these species is not likely. No other herbarium collections revised by the first author in numerous herbaria could be determined with certainty as this species, although a single specimen deposited in the MNHN herbarium in Paris (P), collected by Couderc from Hue between 1883 and 1885, is a possible match for C. sahuynhensis. Re-collection of material from Hue is needed to confirm the identity of this specimen.