Hi Jacks

Over the last few weeks, I’ve been working on a plant survey of a local woodland area of about 30 acres. The low, moist areas are filled with Arisaema triphyllum, (Jack-in-the-pulpit) which is quite common in our area. The first image is what is typical for the species.

Arisaema triphyllum Wake County, NC

I’ve been studying patches of Jack-in-the-pulpit for well over 55 years, always looking for unusual leaf forms that showed any type of patterning. Until last month, I’d never found a single form with atypical foliage. That all changed with my first trip to this local site, where so far, I have found several dozen forms with silver leaf vein patterns. Up until now, there are only two pattern leaf forms of Arisaema triphyllum in cultivation, Arisaema ‘Mrs. French’ and Arisaema ‘Starburst’.

Each patterned leaf clone varies slightly as you would expect within a population including both green and purple stalk coloration.

Arisaema triphyllum silver veined clone
Arisaema triphyllum silver veined clone with green stems
Arisaema triphyllum silver veined clone with purple stems

While I’d never found any true variegation prior to this, I had found plenty of transient leaf patterning caused by Jack-in-the-pulpit rust (Uromyces ari triphylli). This site was no exception, with a number of plants showing the characteristic patterning. If you find these, turn the leaf upside down and you’ll see the small orange rust pustules.

While these may seem exciting, the pattern are not genetic and will disappear without the fungus. Fortunately, this rust can be cured by cutting off the top of the plant and discarding it where the spores can not spread via the wind. Infected plant should be fine, albeit smaller next year. The susceptibility of Arisaema triphyllum to jack-in-the-pulpit rust varies with genetics. Of the tens of thousands of plants I observed at the site, less than 10% were infected with the rust.

Arisaema triphyllum with rust induced pattern
Arisaema triphyllum rust induced pattern on leaf back

Arum world

Arum are a fascinating genus of hardy aroids, known by most gardeners from a single southern European species, Arum italicum. The most popular cultivar of Arum italicum is Arum ‘Marmoratum’. The key to enjoying arums is to not let the seed drop everywhere, since you can get easily get over-arumed. Flowering season is now, followed by seed season. Each seedling has a different pattern from the original, so it’s a personal preference whether to remove seed or not.

Arum italicum ‘Marmoratum’

Arum apulum is a little-know species that is rarely seen in cultivation, native only to a small region of Southern Italy. Our flowering plants in the garden now are from a wild collection made by a plant explorer friend.

Arum apulum

Below is an interesting hybrid between Arum italicum (central to southern continental Europe) and Arum dioscorides (Mediterranean). Arum italicum has patterned leaves, but solid green flowers. Arum dioscoridis has solid green leaves and spotted flowers. The hybrid, Arum ‘Chui’ is an introduction from UK plantsman John Grimshaw. We added the notospecific (hybrid) name Arum x diotalicum. These hybrids have both spotted/speckled leaves and flowers.

Arum x diotalicum