General Plant Information (Edit)
Plant Habit: Herb/Forb
Life cycle: Perennial
Sun Requirements: Partial Shade to Full Shade
Minimum cold hardiness: Zone 5a -28.9 °C (-20 °F) to -26.1 °C (-15 °F)
Maximum recommended zone: Zone 8b
Plant Height: 18 to 24 inches (46-61cm)
Leaves: Unusual foliage color
Spring ephemeral
Fruit: Showy
Other: Red when ripe
Flowers: Showy
Flower Time: Spring
Underground structures: Tuber
Resistances: Rabbit Resistant
Toxicity: Other: All parts of plant contain calcium oxalate crystals, an irritant to the mouth and esophagus. Toxic to cats and dogs.
Propagation: Seeds: Other info: Remove seed(s) from berry which contains chemicals that inhibit germination.
Propagation: Other methods: Offsets
Other: Noted for seldom, if ever, producing offsets.
Containers: Needs excellent drainage in pots
Miscellaneous: Goes Dormant

Image
Common names
  • Japanese Cobra Lily
  • Japanese Jack-in-the-Pulpit
  • Gaudy Jack
  • Circumcised Japanese Jack-in-the-Pulpit
  • Jack in the Pulpit
Botanical names
  • Accepted: Arisaema sikokianum
  • Synonym: Arisaema magnificum

Photo Gallery
Location: RHS Harlow Carr alpine house, Yorkshire
Date: 2019-05-11
Location: in my garden in Del Norte county, Ca. amongst the Redwoods
Date: 2020-04-18
Location: in my garden in Del Norte county, Ca. amongst the Redwoods
Date: 2020-04-18
Location: Meadowlark Botanical Garden, Fairfax, Virginia (May 2022)
Location: Copenhagen, Denmark, EU
Date: 2014-05-03
Location: Chelsea Flower Show, London, UK. 
Date: 2023-05-27
Location: Cary, North Carolina private garden
Date: 2023-03-26
2023 bloom in my woodland garden
Location: Meadowlark Botanical Garden, Fairfax, Virginia (May 2022)
Date: 2022-05-01
Location: Meadowlark Botanical Garden, Fairfax, Virginia (May 2022)
Date: 2022-05-01
Location: Green Spring Gardens Park, Alexandria, VA
Date: May, 2005
Beautiful mass planting of Arisaema sikokianum

photo courtesy of Sunlight Gardens, www.sunlightgardens.com
Location: Harlow Carr garden, Yorkshire, UK
Date: 2015-04-25
Location: z6a MA, my garden
Date: 2013-04-13
Inflorescence way ahead of leaves. Grown indoors.
Location: In my garden in Kalama, Wa. Zone 8b
Date: 2012-04-27
  • Uploaded by Joy
Location: St Louis
Date: 2017-04-04

Date: 2011-05-06
Location: In my garden in Kalama, Wa. Zone 8b
Date: 2012-04-27
  • Uploaded by Joy
Location: In my garden in Kalama, Wa. Zone 8b
Date: 2012-04-27
  • Uploaded by Joy
Location: In my garden in Kalama, Wa.
Date: 2012-04-27
  • Uploaded by Joy
Location: z6a MA, my garden
Date: 2013-03-30
Location: z6a MA, my garden
Date: 2013-04-08

photo by ghislain118
Location: Osaka Prefectural Flower Garden, Osaka, Japan.
Date: April 12, 2008
Photo by KENPEI
Location: In my garden in Kalama, Wa.
Date: 2012-04-27
  • Uploaded by Joy
Location: z6a MA, my garden
Date: 2015-06-20
Apparently happy overwintering in the garden.

Photo Courtesy of Lazy S'S Farm Nursery.
  • Uploaded by Joy

Date: 2009-01-17
photo by ghislain118
Comments:
  • Posted by SongofJoy (Clarksville, TN - Zone 6b) on Jan 14, 2012 11:19 AM concerning plant:
    The flower is composed of a pure white spadix, or Jack, that looks like a big puffy marshmallow and is surrounded by a pitcher that is glowing white inside and dark purple/black on the outside with a dark striped hood. Single flower stalks come up in mid-spring with a pair of 5-lobed glossy green leaves reaching about 12 to 20 inches tall. Unlike many other Arisaemas, the foliage stays up all summer. If the flowers were pollinated (you need at least 2 plants), you may see bright red berried fruits in late summer.

    Japanese Cobra Lily prefers partial to full shade and moderate to moist soil during the growing season. Excessive winter moisture is death to these plants.
Discussion Threads about this plant
Thread Title Last Reply Replies
Whoa! Totally strange... by wcgypsy Apr 29, 2012 12:14 PM 3

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