Warning: Aroids may be habit-forming.
Recently, aroid-tattooed next-generation gardeners have been showing up at Plant Delights Nursery open houses in North Carolina, something that Tony Avent, the nursery’s founder, credits to the current houseplant craze.
Not that Mr. Avent is in the houseplant business, exactly. These first-time visitors are shopping for outdoor relatives of their leafy indoor roommates, their beloved Swiss cheese plant (Monstera), Philodendron and pothos.
They’re in his nursery to inquire about other aroids, an impulse he can understand.
Mr. Avent met his first Arum family member, a native Southeastern species of jack-in-the-pulpit (Arisaema), while exploring the North Carolina woodlands as a child. Now Arisaema and its cousins are among the specialties at his nursery in Raleigh, N.C., which is in its 36th year of operation.
Although his new customers are older than Mr. Avent was when he got hooked, the attraction is the same: These are some seriously strange-looking creatures.
“These new gardeners want something more than their grandmother’s flower garden,” he said. “I’ve always said that a great way to get young people interested in gardening is to start them on aroids, because they’re so odd, like something out of a horror film.”
The Araceae is a family of about 3,700 species, nearly worldwide in distribution but from mostly tropical environments. Its members have in common the basic structure of their flower heads, or inflorescence: a spikelike spadix (in the case of Arisaema, that’s the jack) inside a spathe (the pulpit), a bract that may be brightly colored but isn’t always hooded or pulpit-like. The familiar red Anthurium isn’t.
An aroid’s flowers are tiny and tightly clustered like beads on the spadix, and each is unisexual — either male or female. Whatever the flower head’s overall scale, shape or color, it all adds up to not your average bloom.
There Are Even Aquatic Aroids
You may already be an accidental aroid collector, and not just of houseplants (a group that includes not only the aforementioned Monstera, Philodendron and pothos, but also Spathiphyllum, Aglaonema, Syngonium and more).
A ground-covering variegated arum like Arum italicum may be in your garden. Or maybe you grow one of several native Arisaema, or one of the wide selection from Asia, some known as cobra lilies, for their serpent-shaped spathe.
Most of us have, at one time or another, planted calla lilies (Zantedeschia aethiopica) or Caladium. And few gardeners have escaped the lure of the ever-widening selection of elephant ears (Alocasia and Colocasia). Araceae, all.
Maybe most surprising: The duckweed (Lemna minor) floating in your water garden is an aroid, although a powerful hand lens would be required to make out its flower parts.
It is not the only native aquatic aroid. The water arum (Calla palustris) is found in northern locations; golden club (Orontium aquaticum) is more widespread. Two skunk cabbages — Lysichiton americanum in the West and Symplocarpus foetidus in the East — grow in marshy, boggy places.
For spots with very moist soil or shallow standing water, Mr. Avent said, consider the bold, tropical-looking leaves of the green arrow arum (Peltandra virginica), a native that he thinks is underused by gardeners.
Tuberous Types (Stash Some in Your Sock Drawer)
For those interested in venturing beyond the herbaceous aroids of the windowsill, the next logical step, Mr. Avent suggested, is trying some tuberous types: the Arisaema, callas, caladiums and elephant ears, as well as the less familiar voodoo lilies.
Voodoo lilies include characters like Sauromatum venosum and Amorphophallus konjac, hardy to at least Zone 6a, and the 5b-hardy dragon arum (Dracunculus vulgaris). Both can add unexpected tropical texture to a temperate shade garden, or can be shown off in pots.
Years ago, I took it as a dare when Mr. Avent told me that voodoo lilies were so accommodating I could overwinter the dormant bulblike pieces in my sock drawer if they weren’t hardy this far north. (I use the cellar instead.)
Of course, I was an easy mark, having spent years staring at an engraving of the imposing, dark purple Dracunculus hanging opposite my work table. From “The Temple of Flora” series by various artists, it was published by Robert John Thornton in a homage to the father of taxonomy, Carl Linnaeus, in 1801. But records from the time of the Egyptian pharaohs and the ancient Greeks reveal that aroids have intrigued the human race for far longer than that.
And not just because of their flower heads. The other parts of an aroid can be pretty swell, also — which is no surprise, when you consider that aroid houseplants often captivate us with their leaves alone.
A couple of favorite features: Sauromatum’s leaflets, strung together in a horseshoe-shaped display like so many green pennants, held aloft by eye-catching freckled leaf stalks. And the even more textural leaves of Amorphophallus konjac, sitting on green-spotted pink stalks.
You Sexy Beasts
If their looks are not peculiar enough to tempt you, aroids are also some sexy beasts. The wildest: In an almost animallike manner, the spadix of certain species, including Eastern skunk cabbage, are capable of producing heat. The process of thermogenesis helps the plant to melt snow, pushing through its extra-early bloom.
“It’s as if they say, ‘We’re ready to attract insects to pollinate us, so turn on the stove,’” Mr. Avent said.
The heat may also help volatilize fragrance molecules. In the eight-foot or taller titan arum (Amorphophallus titanum) from Sumatra, Indonesia, that means perfuming the air for one day with the seductive scent of roadkill. What better way to invite a fly or beetle over for an intimate encounter?
That giant plant, endangered in the wild, has lured visitors to botanical garden conservatories, where it is grown not just for show but as part of an ex situ, or off-site, conservation effort. The nonprofit Juniper Level Botanic Garden that Mr. Avent founded on 28 acres surrounding Plant Delights — housing 28,000 taxa, including 2,099 aroids — is part of the effort. And the nursery has propagated and sold some 1,000 young titan arum, presumably to those with high ceilings, if not a proper conservatory. (How to grow this plant.)
In certain aroids, a ramp extends a pollinator welcome. A long tail may extend from the tip of the spathe or spadix, “a guide into the flower that they land on, then crawl along into where the food is,” Mr. Avent said.
Other strokes of genius in the name of an enduring, resilient gene pool: Multiple flowers in the same clump of Amorphophallus may stagger their bloom times, creating a better chance that males and females will coincide and pollination can occur.
And most Arisaema, including the gorgeously striped Japanese cobra lily (A. ringens), change gender some years. They conserve resources by being male (and producing only pollen) while young or under stress, and make female flowers (and then fruit and seed) when the plant’s strength allows.
“Anyone who thinks that nature isn’t smarter than us hasn’t looked at things like pollination biology,” Mr. Avent said.
Elephant Ears, Reimagined
Mr. Avent and I have been digging holes long enough to remember when “elephant ears” meant just a few green-leaved choices. Now the variety of available plants includes those with leaves of green, gold and purple, shiny and matte, some variegated, patterned or edged in contrasting colors.
Part of that change evolved from a chance 2003 meeting with a university-based breeder of one of the oldest domesticated food crops, edible taro (Colocasia esculenta). Mr. Avent was vacationing in Hawaii, where he met John Cho, a pathologist who was breeding taro for disease resistance rather than looks.
But in the deliciously speckled and colorful diversity of Dr. Cho’s genetics, Mr. Avent saw great ornamental potential — a portion of the Colocasia market that Dr. Cho wasn’t familiar with, but in which he became a real force.
Looking Ahead in Aroids
Those Sauromatum venosum that I like so much, it turns out, range naturally from India to Africa, displaying lots of color variation. In India, the spadix is purple; in Ethiopia, it’s yellow. And some are even turquoise, Mr. Avent said.
“Any time you have a plant with a native range like that, there are a lot of possibilities,” he said, forecasting breakthrough colors for gardeners before long.
Other projects: To make Amorphophallus more welcome in homes, work is underway with species that don’t smell bad. He would also like to change their common name, voodoo lilies.
“Call them love lilies,” he suggested, taking a liberty with his interpretation of the first syllable of Amorphophallus. (In fact, the genus name translates as misshapen phallus. Not as catchy.)
Mr. Avent is also eager to increase the availability of well-behaved hybrids of the Asian genus Pinellia, “like jack-in-the-pulpits that flower all summer,” he said. The varieties Polly Spout and Purple Dragon do not seed around wantonly like some Pinellia, but are currently very hard to get.
What is hardy in various locations is changing, too — as breeding evolves, and as more people (tattooed and otherwise) try growing aroids in more places.
“When we started with Amorphophallus 40 years ago, nobody could say, ‘This one is hardy to —,’” Mr. Avent said. “So much of what we’ve learned about aroids is about sharing stories and connecting online. That’s how we rewrite the reference books.”
Margaret Roach is the creator of the website and podcast A Way to Garden, and a book of the same name.