Lilium formosanum
Wallace (1891)
(Formosa Lily / Taiwan Lily)
Overview
Section: Leucolirion
Subsection: Leucolirion (Eastern / Island Trumpet group)
Origin: Endemic to Taiwan; naturalized in Ryukyu Islands, southern Japan, and occasionally in Pacific and tropical regions where introduced
Habitat: Hillsides, open forests, and grasslands from 300–2,000 m elevation
Type: Subtropical to warm-temperate trumpet lily
Status: Locally common in Taiwan but declining in some native localities due to land conversion; often naturalized abroad
Introduction
Lilium formosanum, first described by William Wallace in 1891, is the quintessential lily of Taiwan, a graceful, pure-white trumpet lily thriving from coastal slopes to highland grasslands.
Known widely as the Formosa Lily or Taiwan Lily, it bridges the gap between continental Leucolirion ancestors (L. regale, L. leucanthum) and their insular descendants (L. longiflorum, L. philippinense).
Its adaptability to varying elevations and climates, from tropical lowlands to cool montane zones—has made it one of the most cosmopolitan Lilium species. In the wild it remains a striking component of Taiwan’s late-summer flora, while horticulturally it has become a parent of many modern trumpet hybrids.
Description
A tall, stately perennial reaching 1–2 m in height.
The stem is glabrous, green to purplish, bearing narrow-linear leaves 6–10 cm long.
Each plant produces 1–5 large, funnel-shaped to slightly flaring trumpet flowers, 12–20 cm in length. The tepals are white inside and lightly suffused with purple or reddish-violet externally, especially toward the midribs. The throat may show pale green or yellow shading. Fragrance is strong and sweet, more pronounced toward evening.
The bulb is ovoid and scaly, 3–4 cm in diameter.
Flowering time: July–September (late summer to early autumn).
Chromosome number: 2n = 24.
Ecology and Habitat
Lilium formosanum inhabits open mountain slopes, forest margins, and grassy clearings, often along roadsides and disturbed ground.
It favors well-drained, humus-rich volcanic or alluvial soils, and thrives in both subtropical and cool-temperate zones.
In montane sites it coexists with Miscanthus grasslands; in lowlands it colonizes clearings after typhoons or landslides, illustrating its pioneer ecological character.
Pollination is primarily by hawkmoths (Sphingidae) and large butterflies, guided by the strong fragrance and tubular form of the flower.
Taxonomy and Relationships
L. formosanum belongs to the Eastern / Island Leucolirion lineage, forming a close cluster with L. longiflorum, L. nobilissimum, and L. philippinense.
Molecular phylogenies (Chen et al. 2016; Duan et al. 2022) confirm this monophyletic island group as a southern offshoot of the continental trumpet lilies (L. regale, L. leucanthum).
Within the clade, L. formosanum is often regarded as the intermediate bridge species, morphologically linking the maritime L. longiflorum with the high-altitude L. philippinense.
It is sometimes misidentified with the former due to overlapping ranges, but can be distinguished by its more slender stems, violet exterior tint, and later flowering period.
Varieties and Forms
Several horticultural and regional forms are recognized:
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L. formosanum var. pricei (Franchet) Baker — a dwarf montane form from central Taiwan (1,500–2,500 m), 30–60 cm tall, with smaller but numerous flowers; often considered a separate subspecies or ecological variant.
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L. formosanum var. formosanum — the typical tall, low- to mid-elevation form common along coastal and foothill zones.
-
L. formosanum var. microgaleum (hort.) — horticultural selection with smaller, narrow trumpets, sometimes called “Miniature Formosa Lily.”
All share the same chromosome number (2n = 24) and hybridize freely with L. longiflorum and L. regale.
Phylogenetic Placement
┌── L. regale
┌───────────────┤
│ ├── L. sargentiae
│ ├── L. sulphureum
│ └── L. leucanthum
│
│ Continental Trumpet Lineage
Section
Leucolirion ────────────┤
│
│ ┌── L. longiflorum
│ ├── L. formosanum
│ ├── L. nobilissimum
│ └── L. philippinense
│
│ Eastern / Island Trumpet Lineage
│ (Ryukyu–Taiwan–Philippines; maritime and montane lilies)
│
└── Transitional Himalayan–Southern Line
├── L. puerense
└── L. anhuiense
Cultivation
L. formosanum is among the easiest Leucolirion species to grow.
It tolerates a wide range of temperatures (8–30 °C) and adapts to containers, open beds, or naturalized settings.
Best performance occurs in loose, sandy, well-aerated soil (pH 6–7.5).
It prefers full sun with good drainage and should be planted deeply (15–20 cm).
Seed germination is immediate hypogeal but vigorous; plants often flower within two years from seed—remarkably fast for a true lily.
Because it blooms in late summer, it is a valuable species for hybrid programs, contributing heat tolerance, floriferousness, and resilience to subtropical climates.
Evolutionary and Biogeographic Significance
The species exemplifies the insular dispersal phase of Leucolirion evolution.
From continental China’s trumpet lilies, migration proceeded eastward across the Ryukyu arc into Taiwan.
Here, L. formosanum evolved broad ecological amplitude, allowing colonization from sea level to mountain slopes—traits later refined in L. philippinense toward a montane specialization.
It stands as a pivotal taxon linking the temperate Chinese trumpets and tropical Philippine forms, illustrating how geography, altitude, and climate shaped diversification within the genus Lilium.
Selected References
Wallace, W. “The Formosa Lily: A New Species of Lilium.” The Gardeners’ Chronicle (London), 1891.
Comber, H. F. “A New Classification of the Genus Lilium.” The Lily Yearbook (RHS) 13 (1949): 86–105.
Chen, Y., et al. “Comparative Anatomy and Molecular Relationships of East Asian Leucolirion.” Plant Systematics and Evolution 302 (2016): 195–211.
Duan, Y., et al. “Molecular Phylogeny and Biogeography of Lilium.” Botanical Journal of the Linnean Society 199 (3) (2022): 323–341.
Stearn, W. T. A Handbook of the Genus Lilium. London: Royal Horticultural Society, 1950.
National Parks Board (Singapore). “Propagation Studies on the Endangered Lilium philippinense Baker.” Gardens’ Bulletin Singapore 63 (1 & 2) (2011): 395–404.