Volume 16 > Part 2 > Year 2023 > Page 461 > Zingiberaceae > Curcuma

46. Curcuma roscoeana Wall.wfo-0000365997

Pl. Asiat. Rar. 1: 8, t. 9. 1829.— Hitchenia roscoeana (Wall.) Benth., Gen. Pl. 3: 643. 1883.— Hitcheniopsis roscoeana (Wall.) Loes., Nat. Pflanzenfam., ed.2, 15(A): 572. 1930.

Accepted Name : This is currently accepted.

Synonyms & Citations :

Description : Main rhizome ovoid, 2–4 by 1–2 cm, internally cream-white to pale yellow; branches absent or only a few, if present, ca 0.7 cm diam.; root tubers ovoid to ellipsoid, internally pure white. Leafy shoot 30–90 cm tall, composed of up to 8 leaves; bladeless sheaths 12–28 cm long, green with deep red-purple tinge, pilose to softly pubescent; leaf sheaths 20–22 cm long, green, sometimes with red-purple tinge, sparsely puberulent; ligule obscurely bilobed, 1–2.5 mm long, translucent greenish, hairy on margin; blades ovate to elliptic-ovate, 16–35 by (5.5–)10–13 cm, prominently plicate, mid to dark green above, glabrous or with some hairs along secondary veins, light green below, glabrous, midrib green, glabrous, base slightly oblique, broadly cuneate, rounded to subcordate, apex acuminate; petiole 7–25 cm long, green or with reddish purple tinge, puberulent or glabrous. Inflorescence central; peduncle 15–28 cm long, green, glabrous to puberulent, mostly hidden within pseudostem; thyrse 8–15 by 4–7 cm, composed of 15–45(>50) bracts arranged above each other forming neat rows; bracts obovate, 3.5–5.5 by 2.5–4 cm, connate in basal ½–⅔, greenish yellow at base, gradually becoming deep orange, glabrous or puberulent, apex rounded, strongly reflexed; cincinni with 2–4 flowers at basal bracts; coma bracts absent but uppermost 4–7 bracts sterile and spirally arranged (not in rows); bracteoles ovate, 5–15 by 3–9 mm, folded, hyaline, semitranslucent cream-white, glabrous. Flower gullet type, 4.5–5.5 cm long; ovary barrel-shaped, 2–4 by 2–3 mm, white, glabrous; epigynous glands narrowly cylindrical, 4–5 mm long, cream-white, apex acuminate; style white, glabrous; stigma irregularly capitate with two blunt, dorsal bulges, 1.5 by 1.5 mm, white, ostiole facing forwards, ciliate; calyx 1.4–2 cm long, tridentate, with unilateral incision 4–7 mm long, semitranslucent white, glabrous; floral tube narrowly cylindrical at base, widening distally, 3–4 cm long, externally cream-white to very pale yellow, glabrous, internally with no constriction, cream-white, glabrous at base and apex, puberulous in centre, dorsal corolla lobe elliptic-ovate 0.9–1.4 by 0.5–0.7 cm, concave, apex somewhat hooded, but not mucronate, cream-white, glabrous, lateral corolla lobes bluntly triangular, 0.9–1.4 by 0.4–0.7 cm, concave, cream-white, glabrous, lateral staminodes irregularly elliptic-ovate to bluntly rhomboid with obtuse apex, 1.2–1.5 by 0.8–0.9 cm, cream-white to pale yellow, glabrous; labellum very broadly elliptic-obovate to nearly round, 1.4–1.8 by 1.7–2.2 cm, apex slightly emarginate, cream-white to pale yellow with deep yellow median band extending from base of labellum slightly beyond halfway, base of median band swollen forming two ridges, glabrous, but hairy along either side of median band; stamen ca 9 mm long; filament ca 3 mm long, 3.5–4 mm broad at base, 2.5 mm broad at point of attachment, pale yellow, glabrous or with sparse glandular hair; anther spurless, 5–6 by 2–2.5 mm, connective tissue cream-white to very pale yellow, glabrous or with sparse glandular hair, anther crest rounded, recurved, 1.5–2.5 by 2–3 mm, darker yellow than remainder of connective tissue, glabrous, thecae drop-shaped, 2–2.5 mm long, positioned in basal half of anther, pollen white. Fruit not seen.

Thailand : NORTHERN: Mae Hong Son, Chiang Mai, Lampang, Phrae, Tak; SOUTH-WESTERN: Kanchanaburi.

Distribution : India (Andaman Islands), Myanmar (type).

Ecology : Deciduous forests in limestone areas, 200–700 m alt. Flowering: March–November.

Vernacular : Khachiao som (กระเจียวส้ม).

Uses: Ornamental plant of high horticultural value, often sold as a cut flower.

Notes: The thyrse composed of uniformly orange bracts arranged in neat rows makes this species easy to recognise.