Who wouldn’t want a green dragon in the garden? The problem is that some green dragons are native to North America (Arisaema dracontium) and others are not (Pinellia Pedatisecta). Pinellia is commonly sold as Arisaema dracontium, and since Pinellia is much more aggressive it can take over native areas after well intentioned gardeners plant it.
If you grow either of these plants, make sure you know which one you have.
There is nothing wrong with growing Pinellia in North America; just make sure you label it correctly, and don’t plant it in wild areas.
Comparing Arisaema Dracontium and Pinellia Pedatisecta
I got a “native” green dragon from a local plant sale and it has been growing for a couple of years. It is starting to spread a bit too much for me and I was thinking of moving it to my sugar bush (mostly sugar maples). A friend was by from BotanyCa, a specialty seed house, and we discussed the plant. She took some pictures and soon confirmed that this was not Arisaema dracontium. What!! How could that be?
As it turns out I also have a couple of pots of Arisaema dracontium that I have been growing from seed and they are now flowering. I think they flowered last year for the first time.
I used these two plant sources for the pictures in this post.
We think the Pinellia is pedatisecta. It is the more popular one and it fits the description. At some point I will key it out and update this post if the species name is wrong. It is certainly a pinellia.
I then checked with a number of other authoritative sites that compared these two plants and assembled a list of ways to ID one from the other. The following is a list of those comparisons and my observations.
Arisaema Dracontium is Taller
The documented sizes for these plants is all over the map. Some have the arisaema taller and others the pinellia taller, but most sources say pinellia is smaller.
A. dracontium is reported to grow as tall as 3 feet. The leaves on my plants are already 1.5 ft tall (it is still in the seedling pot).
The Pinellia Flower Reaches Above the Leaves
The first pinellia flower of the season develops before the leaves and grows taller than the leaves. Pinellia can flower several times during the summer and each flowering is taller than the leaves.
Arisaema dracontium has it’s flower below the leaves although the top of the spadix may reach slightly above them. It only flowers once a season and the first flower forms after the leaves show.
Arisaema Dracontium Flowers On the Main Stem
The flower peduncle in A. dracontium starts part way along the pseudostem holding the leaf. In pinellia, the flower peduncle develops right from the tuber. The leaf petiole and peduncle grow out of the ground as separate organs.
When the flower is finished, and if it’s pollinated, the pinellia flower bends over towards the ground in contrast to arisaema, which remains vertical. Unfertilized arisaema flowers, including male only flowers, also bend towards the ground as shown in this young seedling.
Central Leaflet in Pinellia is Longer
Both plants have similar looking compound leaves with numerous leaflets. Some believe arisaema is a bit darker green and pinellia a more yellow-green. This might be true, but not a reliable way to identify these plants. The edges of pinellia leaflets are wavy; arisaema are smooth.
The length of the center leaflet can however be used. This leaflet on pinellia is longer than the leaflets on either side of it. This is true for both more mature plants and smaller immature plants. The center leaflet in A. dracontium is slightly smaller than its neighboring leaflets
Pinellia Pedatisecta Spreads Faster
Pinellia are known for spreading by both offsets and seed, and P. pedatisecta has a reputation of being one of the fastest spreaders. This is why identification of this plant is so important.
Arisaema dracontium spreads too slowly for most gardeners, but it is easy to grow from seed.
I am talking about fused jacks, not confused jacks. Spadix is the proper name for the “jack” in these plants, and in arisaema, it is free from the spathe (the pulpit). In the picture below I removed the spathe that was not fused (attached) to the spathe and you can see it is all gone. In contrast, the back of the spadix in pinellia is partially fused to the spathe. In the picture below I removed the unattached part of the spathe.
Sex and Jacks
Arisaema can be male or female – they are dioecious. Even more interesting is the fact that a given arisaema plant can change its sex from year to year.
Pinellia are monecious. The flower has both male and female parts in the same flower.
The difference between these two flower forms is easily seen in the closeup pictures above. Pinellia has two sections, each with different structures. Arisaema has one type, which I believe is male.
Arisaema Dracontium Forms Red Fruit
The fruit of arisaema is red and each fruit can contain more than one seed.
The fruit of pinellia remains green or whitish-green and each fruit only has one seed. This is true of all pinellia species.
The leaves of arisaema die back in late summer (September) while the leaves on pinellia stay green late into the fall.
Pinellia Pedatisecta Forms Round Tubers
The offsets from the mother tuber are round in pinellia and pear shaped in arisaema. As pinellia grows. the offsets fuse together forming a large single tuber as shown below. I am not sure if A. dracontium does the same (my plant is still too small).
Comparing Arisaema Dracontium and Pinellia Pedatisecta
The two species seem to have several differences that make identification fairly easy. If gardeners take the time to look at them, it should be easy to distinguish one from the other.
Please check your plants so you don’t spread misnamed plants or seeds.