Musing on Arisaema propagation
I can keep bragging about Arisaema for a long time, but this post was triggered last year in early March when I found Arisaema galeatum tuber with emerging roots – a bit too early. So, I started a small scale potting operation in our living room :) On the same time a few Arisaema younglins were already playing under the lights so what better time to muse on cobra lilies propagation?
I have become acquainted and got fond on the cobra lilies while working at Lost Horizons Nursery, a small scale specialty nursery which grows and offers for sale quite a few Arisaema species. Commonly called Jack-in-the-Pulpits and Cobra lilies, they are best known as plants that are propagating through offsets, small tubers that form around/from the old one, but the majority are easily propagated through seeds.
There are reports that some Arisaema species are still dug out from the wild (mostly the ones with a Himalayan distribution) and the tubers offered for sale in bulk by Chinese and Indian nurseries. While you cannot always be sure about the stock origin, be aware in case of big size tubers offered at a lower cost, as very few nurseries are propagating and growing their own plants and if so they cannot be sold at derisory prices. (I would mention A. griffithii, A. franchetianum, A. fargesii and A. candidissimum but probably the list should be longer…) Most often it is lots of fun to propagate and grown your own, not to mention that this way you won’t contribute to the depletion of wild growing Arisaema species.
Propagation by seeds is required in other cases too: species that naturally don’t form tuberlets (A. sikokianum), rare sp. of which you can acquire only a few seeds, in the case of rust infected plants (because it is not transmitted through seeds), for the selection of new varieties or if mass propagation is desired. The setback is that 2-4+ years are needed to have a flowering size plant, depending how well/fast the tuber is increasing in size.
Now it’s the exciting time to seed again – if one would persevere enough, probably species identification after seeds would be possible too! Not a bad idea considering that sometime even from known sources, seeds are not true to species and you can only found out the truth a couple of years later when they flower! Regarding the seeds below, I can only say they are 99% true to type:
Luckily, most Arisaema spp. are easy germinators (I will not go into details for the exceptions). A new Japanese study has found that in same cases, the seeds germinate better if kept dry at room temperature for 1-2 months. The biggest problem is actually managing to get fruits/seeds from some of them (a quirky subject). The second difficulty is then to successfully navigate the highs and lows of their watering requirements.
From green to mosaics of green and orange to red, the fruits are an attractive feature of the Arisaema spp. The seeds have to be cleaned from the pulp (go creative, and wear gloves – the oxalic acid from the pulp can cause irritation of the skin), sowed, and kept warm and moist. Most seedlings will grow a few months and then go dormant once a small tuberlet is formed, to resume its growth only the next year. It is worth mentioning the particular case known for a few species, of germination with protocorm only (no aerial leaf blade forms in the first season, so don’t throw away your pots!).
Giorgio Pozzi in the article: ‘Geophyte seed germination’, came with the idea of inducing an ‘artificial wintering’ of 3 months in order to trick them to start growing during the same season. That’s something interesting to experiment with on a small scale. The tuberlets will increase gradually in size and form tubers of variable shapes and colors depending on the species, which can also be used for ID purposes.
Arisaema is a large genus with lots of species of which unfortunately only two natives to North America: A. triphyllum and A. dracontium. Therefore there is a big variability in regards with their propagation. Care should be taken with a few species that can prove quite ‘weedy’, like A. dracontium, A. flavum and A. serratum and by this I mean that they propagate easily both by seeds and tuberlets when grown in favourable conditions. The propagation through offsets or small tubers (lovingly called ‘tuberlets), which form around/from the old one is very easy. Expect a huge variation among species in the number of offsets/tubers and the way they are produced.
Lots more information on Arisaema species on the Pacific Bulb Society page – HERE.