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Arisaema taiwanense (Formosa Cobra Lily)
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© Lin Scott, some rights reserved (CC-BY) · iNaturalist

Arisaema taiwanense

Formosa Cobra Lily

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At a Glance

HabitUpright
FoliageDeciduous
Height18-30 inches (45-75 cm)
Width12-18 inches (30-45 cm)
Maturity4 years

Growing Zones

USDA Hardiness Zones

5 - 9
These zones indicate the coldest temperatures this plant can typically survive.
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Frost Tolerancehardy

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

Distinguished from A. consanguineum by the generally broader leaflets with less pronounced drip tips and by the spathe coloration, which tends toward green-purple with distinct pale striping. The whip-like spathe tail is present in both species but is proportionally longer in A. taiwanense relative to the spathe body. The palmate leaf with 7–13 radiating leaflets separates it from the trifoliate species such as A. ringens and A. candidissimum.

Appearance

Size & Dimensions

Height1'6" - 2'6"
Width/Spread1' - 1'6"

Reaches mature size in approximately 4 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~3 weeks
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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 striping

Foliage Description

Medium to dark green

Growing 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

Soil Requirements

pH Range5.5 - 6.5(Neutral)
357912
Soil Types
Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

3-4 years

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

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fall

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 5 gallons

⚠️ Toxicity Warning

Toxic to pets and humans