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Arisaema
cultivation etc.
 

INTRODUCTION
The genus Arisaema consists of  200-300 different, mainly spring and summer blooming, rhizome or bulb species.
Arisaema is a fantastic exiting genus with incredibly beautiful flowers, and it deserves a much bigger spreading in our gardens than it is to day.
The genus is not represented in the European flora, which might be one of the reasons, that it is not well known in culture in this country.
It belongs to Araceae, and it mostly look like Arum, if you look what's in culture in Denmark.
The centre for Arisaema growth is Yunnan, but it is also richly represented in Himalaya and the temperate E. Asia. At the east it grows in N. America and Mexico, while Afghanistan makes the frontier to the west, what the temperate an sub tropic species concerns.
The tropic species grows in the height in S. Asia, but is also represented in the mountains in the central and northeast Africa and in the south of the Arabian peninsula.
Some species is found as well in temperate as tropic areas.
The most hardy comes from N. America
, but the most different and the most exiting species comes from China, especially from Yunnan and Sichuan, and from Himalaya. A lot of these species isn't yet named or neither in culture.

BOTANIC DESCRIPTION
The root is a tuber or a rhizome. Those plants who have a rhizome, by the most are evergreen and they mostly grows in tropic areas.
The tubers vary in size and appearance. Some is almost globose, often a little flattened and about 2 cm in diameter, while others in form and size mostly look like a turnip.
Because of the almost globose tubers, it can be difficult to see which way to turn up. Notice that the roots often grows from the upper site of the tuber, and it's here you find the little new bud.
The species which in culture by us, has a tuber that's resting in the winter, and normally starts to grow very late spring. It emergence with a remarkable leaf followed by the flower.

The leaves are very variable. Often there is only one, maybe two big leaves, which is divided in leaflets. The numbers of leaflets vary a lot, but 3 are relative common, as well as the radiated often occurs.
The flower is not a real flower
, but a cornet shaped spathe almost like a Calla, but the Arisaema-spathe is grown together at about the half, (spathe-tube) and the upper part (spathe-limb) either are upright and pointed, or bent over the spathe-tube. Now and then the spathe-limb is extended in a tail-looking, sometimes very long point. The flowering takes 14 days to 1 month. The spathe sits by the most species hidden under the leaf.
In the spathe-tube you find the spadix, on which lower part the real flowers are sitting - groups of changed anthers and stigma. The spadix can be either female or male, or it can be bisexual with the male above and the female under.
Arisaema is one of the very few genus that can chance sex after the circumstances. There is many theories about this phenomenon. The one which the most writers inclines to, is that the sex depends of the conditions of growth and the state of nutrition in the year before.
Bad state of nutrition results in small tubers, which produce male spadix, while big tubers produce female spadix. This probably can be used in culture by fertilizing, so it's possible to produce both male and female plants, and in this way make a better possibility for pollination. Some writers means that young and small plants becomes male, while older and full-grown plants becomes female. But when the plants must be full-grown (or at least have some age), before they produce fertile spadix, the first theory sounds most logical.
A special characteristic of the spadix is, that the upper part vary a lot in form fromspecies to species. This spadix-appendix is important for determining the different species. The appendix can vary from an obtuse club to a trunk or a long tail or whip. By the same time it sends out a special scent which attracts some sorts of insects to pollinate the plant. 
After the pollination the spathe-limb gets slack and curl up.

In the late summer the spadix develops a lot of red, poisonous sharp-tasting berries, and they get sitting long after the leaves are withered down.

NOMENCLATURE.

The existing naming of the species are complex, and there are a countless examples of wrong naming. Al this complicates for the lack of nature- and herbarium studies, and the, now and then, more or less, random naming of the species which are sold in the nurseries. A lot of Arisaema are directly imported and gets sold under the collection-name which is special unreliable.
The first dividing of Arisaema in sections was done by Engler in 1920. He makes a dividing in 15 sections with attach importance to the spathe.

In 1971 Hara makes a revision of this dividing, and now Arisaema gets divided in 13 sections. In this dividing the attach importance especially was to the leaves/leaflets.
Then, in 1984,  Murata makes the newest dividing, where the examinations was done by fresh collected substance, and was based on a comprehensive study in the morphology including chromosomes and pollen. After this 3. dividing the genus gets divided in 11 sections.
In 1990 Murata maked a revision, which until now is the newest, and now he divided in 14 sections:

1.  Anomale
2.
  Arisaema
3.
 Clavata
4.
  Decipienta
5.
  Dochafa
6.
 Fimbriata
7.
  Flagellarisaema
8.
  Franchetiana
9.
 Lobata
10.Nepenthoidea
11.
Pedatisecta
12.
Sinarisaema
13.
Tenuipistillata
14.Tortuosa

ARISAEMA IN NATURE
In nature Arisaema grows in a humus-rich soil, often in mountains-forests. For example the Himalaya-species grows in so different conditions as:
1.
Open sub-alpine slopes.
2.
In the border of temperate forest.
3.
 Under vegetation in high forests.
4.
 On riversides in forest areas.
5.
 In the periphery of sub tropic jungle.
6.
 In sub tropic meadows.

The most areas in the Himalaya gets hit of the monsoon, and through the summers are hot and moist, the winters are cold and dry.
The natural conditions for the most of the Arisaema which has our interest are as following:
1.
The tuber often is places very deep.
2.
Covered with snow in the winter.
3.
 Grows in rock areas in humus rich soil.
4.
 Good drainage.
5.
 Gets a lot of water in the spring and summer.
6.
 Dry at winter.
7.
 By the most in full shade or half shade. Some in full sun, but only in big heights so the temperature don't get too high.

Maybe it's worth to mention that Arisaema not only has aesthetic value, but also is useful as food and medical. For example the Sherpas in Darjeeling and Sikkim use the roots of A. griffithii as flour. But first after a thorough wash out.
In Kashmir and Nepal the roots of A. tortuosum are used, in small doses, against worm at calfs. The seeds mixed with salt are used as a cure against intestinal disease.
The roots from A. speciosum pulverize and uses against snakebite, while the vegetative part are used as pig feed, and that's why this species, in the local area, is called "Pigarisaema".
Be careful if you want to try it - some writers means it's poisonous.

ARISAEMA IN CULTURE
These fascinating plants has become more and more popular in time with the introduction of new species.
Seeds from many new species was distributed from the AGS China Expedition in 1996 (ACE). A great deal are very suitable for the moist woodland, but the hardiness for some species are doubtful, and they maybe must be kept under glass until the plant is well establish, and you can try it outdoors.
We have growing Arisaema in our garden in Denmark (zone 7) for about 10 years, and our experience is, that it, depending of species, survive well if only it get a lot of drainage. Some species are more difficult than others.
A lot of the species are not tested in Denmark, while there is a big doubtfulness about the hardiness.
To grow Arisaema with success, we must try to make the same conditions as in the wild (look Arisaema in nature).
It said that plants from higher areas (in nature) are more hardy against frost.
It's said, that the tuber in nature often is placed very deep. In spite of that, it's both in nature and culture seen, that some species have a tendency to crawl up. Maybe this happens when the soil is too porous? Because it especially happens for the species which are growing in woodland. In our garden we don't have the problem, on the contrary they crawl deeper (we use a good woodland soil, adding some sand and grit).
In Denmark we often have very moist winters with changing frost and thaw, and as well as never a layer of snow for protection.
That's why it's very important that the drainage is in order, and cover eventually with a layer of leaves and a piece of glass in winter. Another solution is to take up the tuber and put it on a cool, non-freezing place in winter. We use the first solution except with  A. speciosum, which we put in a pot in dry soil and keep it  on a non-freezing place in winter (it has a very big turnip-looking tuber, and it's our experience that it easy rots if it's stays outside in winter)
We are planting our Arisaema in a mixture of neutral to acid soil, sand and grit.

In nature the most species grows in full shade or half shade, so a place without directly sun or in partial shade will be good.

The American species are the most hardy.
Arisaema likes a little fertilize in the growing season.

PROPAGATION
 

Arisaema propagate by new small tubers. In some of the species you find these small new tubers away from the old tuber, while they by other species are sticking on the old tuber. Some species (for example A.ciliatum and A.exappendiculatum are spreading by offshoots.
Another way of propagation is by seed. It takes 3 to 4 years or more before the plant gets into flower.
The seeds harvest when mature, and the jelly-like layer removes. This layer often makes a hypersensitivity in form of "burning fingers", so it's a good idea to wear gloves. Clean the seeds in clear water and they are ready to sow. We save the seeds in a refrigerator in winter, and sow it in April. It's our experience that sowing in April gives a better germination. Put the dry seed in water for 48 hours before sowing (change the water now and then). After sowing the seeds germinate 2 to 4 weeks earlier when it has been in soak. Between 75 and 100% germinates.
The most species takes 4 to 8 weeks to germinate, some species not so long (A.flavum). Some species only produce a tuber the first year, and put out a leaf the second year. At some species it takes until 14 month before the seed germinate.
Sow in a soil with a good drainage so the seed don't rot.
To get earlier germination you can place the pot in a warm place with artificial light (21o and 14 hour) Don't forget watering.
Or you can sow the seen in autumn or winter and place it cold and they will germinate at spring.
Some species needs a cold period to germinate (for example A. elephas and A. thunbergii).
Another way of sowing indoor is on a moist piece of paper, and when the seed begins to germinate, then place it in the soil in a pot.
As you can see, the indoor sowing needs a lot of time, but when it takes place in winter, where you can't work in the garden, maybe it would be worth trying.
When the small leaf is getting up, the plant needs a little fertilizer. But be carefully.
The small plants can take a little dry up, but if it gets too much, the tubers gets to rest, which's not a good idea. Contrary you must try to get the tuber in growing as long as possible to get it big before winter.
In the autumn when the leaves gets yellow and fall, the tuber gets in rest, and the watering minimizes so the soil just are moist (to dry is better than to wet).
If you have started the sowing indoor the tubers sometimes get to rest in the beginning of summer.
Some species as for example A. jacquemontii grows until late summer, so you go on with watering and fertilizing until the leaves begin to fall.
Let the small seedlings stay in the sowing pot the first 2 years before you prick out. It gives a better surviving as if you prick out in the first year.
At the page of description you can see some of the species which grows in Danish gardens. The most we have grown ourselves with fairly success.

But we must admit, that every spring, we wait in suspense to se what's coming up. And it's a long "pain" because the first emergence in April and last year the last Arisaema emergence in the second half of June. On the other hand only one didn't came up.
If you want to study more about Arisaema I recommend you to get the book "The Genus Arisaema" written by Guy and Liliane Gusman. It is a very fine book with a lot of photos, and, what I think is almost the best, coloured drawings of the spathe and leaf of each species.
 

 

 

 

Arisaema sikokianum

 

 

 

 

Arisaema thungergii subsp. urashima
 

 

 

 

 

Arisaema franchetianum

 

 

 

 

 

Arisaema dilatatum

 

 

 

 

 

Arisaema utile

 

 

 

 

 

Arisaema lobatum

 

 

 

 

 

Arisaema kiushianum

 

 

 

 

 

Arisaema sikokianum

 

 

 

 

 

Arisaema nepenthoides

 

 

 

 

 

Arisaema griffithii

 

 

 

 

 

Arisaema engleri