Scientific name: Lilium procumbens Aver. & N.TanakaEnglish name: Vietnamese name: Other name:
Herb terrestrial or lithophytic, bulbiferous, perennial. Bulb situated at 8–12 cm below the surface of the ground, subglobose to ovoid, (2)2.5–3(4) cm in diam., without a tunic; scales many, narrowly ovate to broadly lanceolate, white, fleshy, imbricate, (1.5)2–2.5(3) cm long. Aerial stem slender, unbranched, procumbent, pendulous or climbing, 1–1.5(2) m long, 3–5(6) mm in diam., leafy throughout, sparsely papillose in apical third, with whorls of many dense roots and few bulbils at nodes above the bulb; internodes (1.5)2–4(5) cm long. Leaves many, alternate, distant, more or less horizontal (to stem), broadly lanceolate to narrowly ovate, (6)8–16(18) cm long, (1.5)2–2.5(2.8) cm wide, glabrous, abaxially with 3 prominent veins, apex attenuate or acute, base sessile or subsessile, often narrowed into short petiole (1)2–5(6) mm long, 1.5–2 mm wide. Flowers solitary (or 2 to 3 in terminal raceme), campanulate-funnel form, nodding, slightly zygomorphic, white with green tint, rarely with very few sparse purple marks along margin near the base of outer tepals (sepals). Tepals 6, free, spatulate or narrowly obovate, (4.6)4.8–5.2(5.4) cm long, (1.3)1.4–1.5(1.6) cm wide; in adaxial proximal half involute laterally and medial longitudinal narrow part (midrib zone) green, glabrous and nectariferous; in distal half nearly flat and not strongly recurved; the inner 3 (petals) slightly wider than the outer 3 (sepals); medial portion prominently keeled abaxially; the keel rectangular in cross section. Stamens 6; filaments light greenish to almost white, filiform, glabrous, recurved distally, 3.5–4 cm long; anthers narrowly oblong-ellipsoid, slightly arcuate, dorsifixed, rotatable, brown-orange, 6–7 mm long, 2.5–3 mm in diam. Pistil slightly shorter than stamens; ovary erect, straight, narrowly conoid, longitudinally shallowly grooved, 9–10 mm long, 1.5–2(2.5) mm in diam. near base, 3-loculed; ovules many per locule; style slender, gradually slightly broadened towards apex, slightly curved upward, 2.2–2.4 cm long; stigma subcapitate, apically subtruncate, 3-lobed, 4–4.5 mm across, light greenish to white, densely papillose.
Fruit a light brownish capsule; seeds numerous, flat, winged around.
Etymology: The specific epithet refers to the procumbent habit of the plant.
Distribution: Endemic to VIETNAM, Cao Bang province (Nguyen Binh district, Ca Thanh municipality).
Habitat, phenology and conservation status: Terrestrial or lithophytic, bulbiferous herb with a climbing or procumbent to pendulous slender stem. Primary mixed forests of broad-leaved trees and conifers like Pseudotsuga sinensis on karstic rocky limestone, common on very steep rocky slopes and on shelves of shady cliffs near mountain tops. 1300–1500 m a.s.l. Flowers in July in cultivation.
This species is rare and is regarded as endangerous (EN) according to IUCN Red List criteria.
Notes: Lilium procumbens is morphologically similar to L. poilanei Gagnep. described from northwestern Vietnam and northern Laos and also to L. primulinum var. ochraceum (Franch.) Stearn known from Guizhou, Sichuan and NW Yunnan in China (Liang and Tamura, 2000). It markedly differs from them in having a more slender, procumbent stem, and smaller, white, stellately campanulate-funnel form flowers with slightly or moderately recurved, narrowly obovate tepals and a pistil shorter than the stamens. In natural habitats, the new species grows on very steep rocky slopes and on shelves of vertical cliffs of limestone near mountain tops. The slender stem was climbing among dense shrubs or procumbent or drooping among mossy cliffy rocks. The slender, procumbent habit of the stem is stably retained in cultivation. Sterile stems to the end of vegetative period commonly form persistent bulbils in axils of apical leaves.