Arisaema, Arisaema, Arisaema

by Tony Avent, Plant Delights Nursery Inc.

IN THE BEGINNING, THERE WAS ARISAEMA TRIPHYLLUM
I remember being fascinated by these bizarre plants as I roamed the woods as a child, here in piedmont North Carolina. The native species A. triphyllum was so variable, that it made each plant seem special. A trip one week would find the new leaves just pushing through the leaf debris. Rushing home from school and out into the woods a few days later would find the unfurling flowers. Still later in the week, the purple coloration would be evident as I picked out my favorite plant.
Having only two native species, A. triphyllum and A. dracontium I longed to see more of what the genus offered. Unfortunately when the continents broke apart, most of the really wonderful species headed for Asia. Although a few seed would occasionally make their way into this country, it wasn't until the 1990's that we really began to gain access to many of the nearly 150 species of mostly Asian arisaema.
Our native Arisaema triphyllum and A. dracontium are two of the most hardy species, with each growing well into zone 3 and 4. There are a number of forms/subspecies of each varying in size and color of the flower. We'll leave the arguing over these to the taxonomists.
In 1996, I was fortunate to spend a month in Yunnan, China studying arisaema, followed in the fall of 1997 with a similar trip to Korea. In the interim time, our friend Barry Yinger has helped us set of a connection with a Japanese nursery that produces a variety of arisaema from seed. Thanks to a "harmonic arisaema convergence" we are now able to supply one of the finest collections of propagated arisaema in the country.
ARISAEMA SEX:
Arisaema flowers consist of many parts, the two most prominent are the spathe and spadix. The spathe is the hood of the pitcher, while the spadix is the "stalk" inside the flower that holds the sex organs. In some species the spathe develops into a long threadlike tail, while in other species, it is the spadix that copies this habit.
If you are the voyeuristic type, then you will love arisaemas. Arisaema plants are one of the more unique members of the plant kingdom. Some plants are male, some are female, some are both, and some change back and forth (paradioecious). As a general rule, arisaemas are male when young, then when they build up enough energy to have babies, they switch and become female. The year after giving birth (fruiting), they will often revert back to being male.
There are only a few arisaema species that always have both sexes on the same plant. They are A. flavum (always), A. tortuosum (when mature), A. consanguineum (when mature), A. heterophyllum (when mature), and A. dracontium (when mature but not self fertile).
MEXICAN SPECIES:
We strongly feel that the exploration of Mexico will result in a number of new arisaema species. While there are only 2 documented species, plant exploration by John Fairey and Carl Shoenfeld at Yucca Do seems to have already resulted in 6 very different collections (species?). We anxiously await these species getting into the trade for further study.
ASIAN SPECIES:
My first encounter with an Asian arisaema was A. sikokianum. This Japanese native was truly one of the most popular plant imports from Japan for a reason. The stunning black purple pitcher contrasted dramatically with the white center. I remember the $100 price tag, that left me with the feeling that I would never be able to own one of these gems. Finally the abundance of both imports and seed producing plants have brought the price into a more affordable range.
The next of the Asian species to grace my garden was Arisaema ringens...the cobra lily. This Japanese and Korean species occurs in very low areas in densely shaded woods. I was fortunate to find this species on my 1997 Korean expedition. The large trifoliate leaves serves as a backdrop to the wonderful flowers. Arisaema ringens is very early to emerge in spring, and should be protected when a late frost is imminent. Conversely, the seed are the last to ripen, often 2-3 months after the foliage has died away (around Christmas).
One of the easy to grow, but spectacular species is the giant Arisaema consanguineum. Hopelessly confused with A. erubescens, this arisaema has one of the widest distribution ranges of any species. Throughout our entire trip to China, we found Arisaema consanguineum from the tropical zone 11 areas to the top of alpine mountains at 15,000' near Tibet.
Arisaema vary as to their emergence dates in spring. For us the first species to emerge is A. japonicum (late February), followed soon by A. ringens, the in late March by A. sikokianum. A. consanguineum, A. flavum, and A. candidissimum often don't emerge until May or June in the south. You will need a great deal of patience to grow these species. Many of these species are not even shade plants. Arisaema candidissimum grows among dry sunny boulders on baking hillsides. A. flavum is also a species that prefers sun to shade.
I will admit to almost having given up after killing hundreds of the himalayan species (i.e. A. griffithii, A. intermedium, A. speciosum, A. costatum, A. jacquemontii, and A. nepenthoides). According to Guy Gussman and Wilbert Hettersheid who have had similar experiences, these tubers do not like to be dry during their dormant season (opposite of most other species). It seems that their roots remain growing during dormancy and must not be allowed to dry.
PROPAGATION:
Propagation of arisaema is almost entirely from seed. To get seed of most species, you will need both a male and female plant (see Arisaema sex). Obviously, the more plants of a particular species, the more chances for setting seed.
After the seed are harvested, they should be first cleaned (the pulp contains a germination inhibitor). The easiest way to clean arisaema seed is to put the ripe seed into a ziploc bag (the fruit are toxic and can cause severe skin irritation and numbness) and "squish" the pulp from the seed. After adequate squishing has been complete, pour the mess into a cup of water. Decant the pulp several times, and you will quickly have a cup of clean seed.
Arisaema seed can be planted in a pot of potting soil indoors immediately after cleaning. The seed should be covered lightly with potting soil. Arisaema seed will usually sprout within 4-6 weeks and will proceed to grow for up to 2-4 months. At this time, they will appear to slowly turn yellow and die. Fear not, for they are only going dormant. When dormant, arisaemas in containers must not be kept wet...this is certain death for most species. I keep my plants in containers and water only when the soil gets bone dry...about twice a month.
These arisaemas may be kept this way until winter, when after a cold period, they will again resprout. Some of the warmer growing species will actually resprout during the summer and put on an extra growth cycle (especially A. consanguineum). To squeeze out an extra season, the dormant plants can be refrigerated for 3 months during the spring/summer. This can be accomplished in the container (if your refrigerator and spouse will allow) or by placing the tubers in a ziploc bag of slightly moist peat(easier to store in the refrigerator). After this time, they will resprout and can often be forced into two seasons of growth during a calender year.
From seed, expect it to take 2-4 years to have a flowering size plant...depending on species. The size of the seed determines the amount of food reserves, and consequently how large the plants will grow during the first season. A. franchetianum, A. candidissimum, and A. taiwanense get quite large from seed during the first growing season.
The are other extremes, (i.e. Arisaema elephas, A. thunbergii, and A. urashima), which only sends out a root during the first season. Only after a dormancy period the new leaf emerges. This could have been easily predicted due to the tiny size of the seed in this species, as compared to the relatively large seed size of those mentioned above.
While tissue culture has been attempted on arisaema, their complex dormancy patterns and difficulty of sterilization, has here to for rendered such impossible.
Some of the arisaema species actually multiply by offsets. Arisaema candidissimum, A. amurense, A. concinnum, A. costatum, A. exappendiculatum, A. ringens, and A. ternatipartitum are good candidates for this mode of propagation. The small offset bulbs/runners can be snapped off and replanted at the end of the growing season in fall.
ARISAEMA DISEASES:
Fortunately, diseases that affect arisaema are rare. About the only problem is from a rust fungus (Uromyces ari- triphylli). The fungus appears usually on the underside of the foliage, and is evident as the foliage unfurls. There is little that can be done, except to discard the tuber to prevent spread. Occasionally, this can be seen in the wild on A. triphyllum.