4/29/21 Jack Season

The first bloom of tender spring ephemerals is winding down, but on brushy hillsides where few other wildflowers grow, one tough little plant is coming into its own.

Jack-in-the-pulpit, Arisaema triphyllum, first emerges from its corm as a fleshy sheath enfolding the baby leaves…

…which soon push skyward and begin to unfold.

Though Jack-in-the-pulpit is relatively abundant in some parts of this forest, the density of the population on this particular hillside is surprising. It’s been about eight years since the large, heavily shading Bush honeysuckles that dominated this site were removed; since then the small light-starved Jacks have rebounded and spread happily .

I spent an entire afternoon, mostly on hands and knees and sometimes prone, to collect these images.

It was like a treasure hunt – finding one Jack after another after another, each with it’s own unique personality.

Jack is part of an ancient lineage; the Araceae or Arum family is one of the oldest angiosperm families, with fossil records from the late Cretaceous. Perhaps this accounts for its unique reproductive structures, consisting of a protective spathe sheltering a clublike spadix.

I’ve found no explanation other than “genetic variation” for why some Jacks are all green. The flowers are not trying to attract bees or butterflies so bright colors likely don’t matter.

Instead, Jack’s mushroom-like odor attracts tiny insects, particularly fungus gnats. Since the inside of the spathe is slippery and steep, male flowers have a tiny exit hole near the base of the spathe. Female flowers however, don’t allow gnats to escape, helping ensure pollination. I have to wonder if carnivorous plants might have evolved in this fashion.

Something (not me) has removed the spathe from this female flower, revealing its floral anatomy. The actual flowers surround the lower part of the spadix. The presence of two leaves on this plant indicate it’s a female – this year anyway. Jack may also be Jill, since this species is a “sequential hermaphrodite”, able to modify or switch gender in response to the age of the plant and amount of stored energy. Female plants need more stored energy to ripen seeds, but may switch back to mostly male flowers the following season.

Most of the plants on this hillside are female, so they must be thriving. Increased sunlight is likely a factor, due to invasive plant removal and the loss of large ash trees to the Emerald ash borer. Though there is increased competition in the herbaceous layer, Jack seems deal with it just fine. I have found big healthy plants deep in brushy thickets of blackberries.

It will be interesting to see how successful their reproductive efforts are, based on the number of berry laden stems later this summer. Though deer do bite off some of the flowers, hopefully they will not develop a preference for them.

22 thoughts on “4/29/21 Jack Season

  1. Ginny

    Fascinating, Rosemary! I have been on a wildflower hunt this spring, hiking lots of trails from the Louisville Nature Center to Mammoth Cave and have come across many that are new to me. I was just commenting to a friend on a hike last week that I rarely see Jack’s in groups. I seem to most often spy one here and one there, sometimes in close proximity but not really together. I’ll have to get over to the LNC and check out that hillside you mentioned!

    Liked by 1 person

  2. Phyllis Fitzgerald

    I have a few in my garden. I also have an abundance of Arum–same family, but non-native, I think. Before this post, I did not know for sure that they were the same family, but good to finally know. The Arum that are amazingly decorative seem to be a bit invasive, but that’s OK, since they are so beautiful, year round!

    Liked by 1 person

  3. tonytomeo

    Those really are WEIRD floral structures. Their choices of pollinators are weird too. My dragon lily, which bloomed so spectacularly last year, does not seem to be wanting to bloom this year. A calla off the edge of the road is blooming nicely though. It does not seem to have a season. There is nothing here like yours though.

    Liked by 1 person

      1. tonytomeo

        Plant Delights has quite a few arums available from their catalog. Some are native to eastern North America. It seems weird that so many are native there while none live here, where we are famous for botanical diversity.

        Liked by 1 person

      2. tonytomeo

        Disjunct distributions are a trip! It seems that if genera were to move in from Asia, that they would be in the West. Well, it seems that way to me, because I would think that it would take them a long time to get across the continent, . . . . as if they did not have long enough to do it by now. When studying the Sapindus saponaria that I met in Oklahoma, I found that it is native to both Oklahoma AND Hawaii. This is not separate species within the same genus, but is actually the same species. Birds do not carry the big seed. I just can not imagine how that happened!

        Liked by 1 person

      3. oneforestfragment

        There are some genera in the humid west, along the coast, etc. But ancient climate change likely doomed the rest. This disjunct business also explains why we’ve had so many pest plagues kill off trees like the chestnut and the ash, and why some introduced asian species have become so obnoxiously invasive.

        Liked by 1 person

      4. tonytomeo

        Those sorts of problems are generally introduced rather than naturally occurring disjunct populations. Biological organisms move around the World more than they ever have before, which is why we all wear masks now!


  4. shoreacres

    I’ve found these only in fall, when the bright berries attracted my attention. I’ve not been able to get back to the east Texas woods this spring for a variety of reasons, but I’m hoping that when I do get there, I can find some in earlier stages of development. Thanks so much for all of the information, and for the wonderful photos. Now I have a guide to take with me when I go looking for this unusual plant.

    Liked by 1 person

    1. oneforestfragment

      I have never tried the root but have heard that it’s sharp! Sounds like you are from the east originally. We lived in coastal N. CA for many years, but now will be transitioning form KY to our own little homestead in the mountains of SW VA.


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