Arisaema taiwanense
Formosa cobra lily
Overview
Arisaema taiwanense is a tuberous perennial reaching 18–30 inches (45–75 cm) tall with a spread of 12–18 inches (30–45 cm). A single pseudostem supports one palmate leaf divided into 7–13 narrow, lance-shaped leaflets radiating from a central point, each leaflet 4–7 inches (10–18 cm) long with tapered tips. The spathe is 5–8 inches (13–20 cm) long, green to purple-brown with pale longitudinal striping, terminating in a long, whip-like tail that extends 6–12 inches (15–30 cm) beyond the hood. The spadix is elongated and threadlike, extending well beyond the spathe opening. Clusters of bright red berries, each 0.3 inch (8 mm) in diameter, develop on female plants by late summer and ripen in early fall. Growth emerges in mid to late spring. Plants are sequentially hermaphroditic, typically functioning as male when young and transitioning to female as tuber size increases over several years. Foliage senesces and disappears by mid-fall. Tubers are vulnerable to rot in poorly drained winter soils, and slugs feed on emerging growth in spring.
Native Range
Arisaema taiwanense is native to Taiwan, where it occurs in montane forests and along forest margins. It grows at elevations of 3,300–8,200 feet (1,000–2,500 m) in humus-rich, moist but well-drained soils under deciduous and mixed forest canopy.Suggested Uses
Planted in woodland gardens and shaded borders at 15–18 inch (38–45 cm) spacing among ferns, hostas, and other shade perennials that fill the space during winter dormancy. Grown in containers of at least 5 gallons (19 L) in a humus-rich, freely draining mix. The tall pseudostem and radiating leaflets create a canopy effect similar to A. consanguineum in understory plantings.How to Identify
Appearance
Size & Dimensions
Height1'6" - 2'6"
Width/Spread1' - 1'6"
Reaches mature size in approximately 4 years
Bloom Information
Flowers appear in May–June in zones 7–9 and June–July in zones 5–6. The spathe persists for 2–3 weeks before collapsing. Fruit clusters develop on female plants and ripen to bright red by September–October. Young plants may produce only male inflorescences for the first 2–3 years.
Detailed Descriptions
Flower Description
Green to purple-brown with pale stripingFoliage Description
Medium to dark greenGrowing Conditions
Sun Requirements
Requires 2-5 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Plant tubers 4–6 inches (10–15 cm) deep in humus-rich, well-drained soil in fall or early spring. Consistent moisture during the growing season supports foliage development and fruit production; drought causes premature leaf senescence. Winter drainage is critical—tubers rot in waterlogged soils during dormancy. Slugs and snails damage emerging shoots in wet spring conditions. Plants typically require 3–4 years from a newly planted tuber to reach female flowering stage. Mark planting locations to avoid accidental disturbance during the dormant period from November through April.Pruning
No pruning required. Spent spathes collapse and decompose naturally. Foliage yellows and senesces in fall; spent leaves can be removed once fully brown or left to decompose in place. Berry clusters can be left for seed collection or removed to prevent self-sowing.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
fall
Container Growing
✓ Suitable for container growing
Minimum container size: 5 gallons