Arisaema ringens border

Plant of the Month June 2023


I was fascinated by “Jack-in-the-Pulpits” as a child in England. Arum maculatum grew in our woods. We also called it Lords-and-Ladies and Cuckoo-Pint. Was there something improper about the plant? I recently learned “pint” was a shortening of “pintle” (penis!) My Grandmother had a scary, smelly Voodoo-Lily (Amorphophallus konjak) in her garden. Now I find Arisaema triphyllum growing in our Ontario woodlands.

All three are among 140 genera of the Aroid family, or Araceae. These are characterized by a large, frequently colourful, upright to curled over bract called a spathe (pulpit). This encloses the spadix (Jack), which is an upright thick stalk bearing numerous male and/or female flowers. When teaching, I liked to show teen-aged students a small Arisaema triphyllum and tell them it was a male plant. It would be female the next year if it grew big and strong enough! Seed production might exhaust it and it would return to being a male plant! (Paradioecious, changing back and forth.)

Synonym: Arisaema praecox. Arisaema sieboldii. Arum ringens.

Common Name: Japanese Cobra Lily.


    Arisaema ringens ‘Black Mamba’ – dark purple pseudostems.

    Arisaema ringens var. glaucescens – green spathe.

Arisaema ringens

Arisaema ringens.

Life Cycle: Perennial, growing from disc shaped tubers. 

Size: to 0.5m x 0.5m.

Bloom Time: The plant usually emerges during the first week of May in Toronto. The inflorescences open soon after, in mid May to June.

Arisaema ringens mid May

Arisaema ringens early May.

Leaves: A mottled purple pseudostem bears 2 long lasting glossy trifoliate leaves. The 3 leaflets are oval to elliptical and about 15 cm long. The leaves die down in late summer if no seeds develop.

Arisaema ringens leaves

Arisaema ringens - leaves.

Flower Colour & Size: Long lasting Arum flowers. The thick spathe, striped in green, purple and white curls forward and down, looking like the head of a cobra.

Arisaema ringens 4 plants

Arisaema ringens – four inflorescences.

The glimpse of the shiny purple interior gives the impression of 2 eyes. The creamy coloured spadix is hidden inside. The tiny flowers are usually male or female with an occasional hermaphrodite plant.

Arisaema ringens spadex

Arisaema ringens close up

                      Arisaema ringens – closeup.                                  Arisaema ringens – female.

Fruit: Red berries in fall, if male and female plants present. I have had berries once which did not develop.

Range: China, Japan, Korea.

Habitat: Lowland woods.


Plant: Plant dormant tubers in fall, at least 10 cm deep with a handful of gravel mixed below.

Light: Part to full shade.

Soil: Humus rich, well drained soil. Avoid heavy clay.

Water: Medium moisture to wet soil, though my plants dry out frequently.

USDA Hardiness: Zones 5-9.

Companion planting: Woodland plants – Ferns, Hosta, Stylophorum diphyllum (wood-poppy), and if light shade,  Hakonechloa macra 'Aureola' (Japanese forest grass). 

Propagation: Dig plant in fall and separate tubers - replant. From seed: Remove fleshy coat. (Use gloves.) Gently scarify. Soak in hand-hot water for 24 hours. Plant and keep at 20°C. Let seedlings grow for as long as possible, feeding with an all purpose fertilizer. Keep at 4°C over winter.

Problems:  None noted. The plant is poisonous.


Text and images supplied by Anna Leggatt (Toronto Master Gardener)