Re-Imagining Indigofera
If you’re anything like me, you’re constantly trying to figure out ways to get the most out of your leafy landscape companions. Whether it be eating the literal fruits of their labor, cutting fresh flowers for indoor arrangements, or learning how to make natural dyes from various plant materials, the ethnobotanical uses of our beloved garden buddies are seemingly boundless. Unfortunately, many of our traditional practices have gotten lost with time and the evolution of technology and synthetic materials – our fruits harvested thousands of miles away in different countries, last-minute bouquets of cut flowers purchased for loved ones at grocery stores, pre-made fabrics and man-made dyes that adorn our bodies day in and day out. Sometimes, the disconnect gets so overwhelming that there’s only one thing to do: return to nature. This is the season of berry-picking, frolicking through wildflower fields, and experimenting with the natural world around us, should we allow ourselves the whimsy with which to explore. The most curious of inquisitive horticultural minds may find themselves mashing and boiling plant materials to discover a heavily pigmented end result. But, where to start?
How about starting with one of the oldest and most sought-after natural pigments in human history? Indigo, which has its own spot on the ROYGBIV acronym and falls somewhere in the range of a denim-blue, is actually a naturally derived pigment from a genus of plants known, non-coincidentally, as Indigofera. For nomenclature geeks, indigo- refers very literally to the natural blue hue, while -fera means “to bear” – quite literally, the plants are indigo-bearing monsters. But wait, this pink flowering plant with soft bluish-green leaves is capable of producing a deep, rich, long-lasting pigment? You’re darn tootin’ it is. It is actually the leaves of the plant, which undergo a fermentation process of several days, that produce the coveted dye; a process that can easily be recreated with household materials and some spare time.
Although Indigofera tinctoria and Indigofera arrecta are considered the two best species of the genus with the abilities to produce “true” indigo pigments, other members of the genus are more than capable and have often been utilized in combination with or separate from I. tinctoria. With over 750 different species in the genus, it’s no wonder that several of them are capable of creating natural pigment. Others, however, are revered for their medicinal and ornamental properties, such as Indigofera ambylantha and Indigofera heterantha (syn. gerardiana). With a genus as large as Indigofera, it’s expected that several species would get lost in the sauce. I. ambylantha and I. heterantha are two species of indigo that have fallen into ornamental obscurity, and are rarely, if ever, used in the landscape. The cultural information available for each seems rather redundant, leaving out long-lost ethnobotanical uses and ecological importance. Perhaps at one time, each species had been used in an attempt to recreate the natural indigo pigment, but any records of such efforts are nearly impossible to find or don’t exist at all. So, what better to find out their capabilities than by doing a small homegrown experiment?
Although it’s considered best to harvest indigo leaves after the phytochemistry of the plant has been altered by the heat of the summer, typically in late August to early September, for the sake of our experiment this week, I harvested fresh leaves from both species about a month early. Indigofera heterantha has noticeably more leaf content, with tidy pink inflorescences peeking through dense, yet delicate, foliage. Indigofera ambylantha, on the other hand, is a bit of an oddball – its vertical flower racemes stand candle-like protruding from their stiff, wiry stems, with semi-sparse foliage filling out the base of the shrub. Both have staggeringly long flowering times, often beginning in May and pushing out final blooms in September. The blue-green, compound foliage, our aforementioned pigment protagonist that is characteristic of both species as well as a majority of notable species within the genus, provides a feathery texture to the landscape. Both species perform particularly well with some light to dappled shade, each getting to be between 4-6’ high and wide, and possessing the ability to become relatively drought tolerant once established. Like other Fabaceae family members, Indigofera are helpful for nitrogen fixation in poor soils, and have been proven helpful in bioremediation projects for the accumulation of undesirable excess minerals such as lead and caumium.
Besides their long-standing use in the textile industry, the leaves of various Indigofera species are also found to contain beneficial medicinal compounds. Purified extracts of Indigofera species were found to have a seemingly endless list of biological activities, including but not limited to possessing anticancer, anti-inflammatory, antioxidant, gastroprotective, analgesic and anticonvulsant properties. Indigofera heterantha, Himalayan indigo, has specifically been found to contain antibacterial, antifungal, and vermifuge properties, while Indigofera ambylantha extracts exhibit analgesic and hemostatic phytocompounds. Indigofera deserves a place not only in the artist’s garden, but the gardens of the herbalist and the historian as well.
But, back to our crude and somewhat primitive experiment. After gathering leaves from both species and tying them together with their own stems, I boiled enough water to just cover the material in their containers and poured it over top. Next, I found some heavy rocks to help weigh the leaves down and encourage their leaves to release pigment. Next came cloth towels, and the very technical application of recycled nursery pots to shield them from the elements. With a wish and a prayer, I returned after 24 hours with baited breath. And what, to my wandering eyes did appear? Behold – plant dye! Granted, it needs several days longer for an attempt to ferment, and I went with the non-mash method of simply placing the leaves into the jars, so the unfinished product after 24 hours resulted in two very different tea-colored shades of amber red (Indigofera heterantha) and deep, ochre-y brown (Indigofera ambylantha… with a hint of dark blue, if I’m not imagining things). After replacing the leaves and rocks into their baths, complete with dish towels and nursery cans, I once again retreated from my elementary experiment until next week, when I’ll return to discover if the current pigments have evolved. (Look out for an update!) It just goes to show that even if you don’t necessarily get the results that you expect or desire, that playing around with your plants can unlock their unknown secrets and satisfy your inner child at the same time.
Ready to get into Indigofera? Check out our availability and add them to your next project.
Indigofera amblyantha (Indigofera) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)
How to Grow and Care for Indigo Plants | Gardener’s Path (gardenerspath.com)
Plant of the Month: Indigo - JSTOR Daily
ENH1378/EP642: Indigo from Indigofera spp.: Historical and Cultural Overview (ufl.edu)
*New* Fresh Indigo & Woad Spectrum Tutorial — the dogwood dyer
The Process: Indigo from Plant to Paste – THE KINDCRAFT
Dyeing with Indigo - Maine Organic Farmers and Gardeners (mofga.org)
Indigo Plant Information – What Are Some Different Types Of Indigo | Gardening Know How
Phamphlet on indigo - Sir George Watt - Google Books
Indigo: plant of culture and color – CornellBotanicGardens
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