Inside The New York Botanical Garden

The Body Electric

Posted in Around the Garden, Learning Experiences on April 12 2012, by Daniel Atha

Daniel Atha is an Associate Editor of NYBG‘s systemic botany journal, Brittonia, and a researcher specializing in floristics, taxonomy, and economic botany. He has taught classes in anatomy and systemics at the Garden’s School of Professional Horticulture and is currently working on a project to develop identifying DNA barcodes for plants of the Northeastern United States.

“I knew a man, a common farmer, the father of five sons,
And in them the fathers of sons, and in them the fathers of sons.”

–Walt Whitman, “I Sing the Body Electric,” from Leaves of Grass, 1855

Urtica dioica L. (stinging nettle)

If told there was a substance promising that each of our five sons, and each of their five sons would grow up to be “massive, clean, tan-faced, handsome,” would we approach that substance with caution, treating it with respect and gratitude? Or would we rush out, blindly gathering as much as we could? Well… Mother Nature must have seen us coming because, while she created just such material, she cleverly devised a way to ensure we respect it.

The “substance” of course is stinging nettle. And of all the matter on earth, nettles come closest to providing our every need in one convenient package. Nettles help us grow strong and they keep us healthy and happy for life. Along the way they feed us, clothe us, transport us, soothe our pains and they even make us beautiful. Want more? They give it, body and soul, sacrificing all for the next generation.

Nettles are a “perfect food,” containing vitamin A, vitamin B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (panothenic acid), vitamin C, vitamin D, vitamin E, vitamin K, acetycholine, calcium, chlorophyll, chromium, iron, magnesium, potassium, selenium, serotonin, sulphur and zinc. And like only a handful of plants, they pack plenty of protein. Fortified with nettles, our immune systems have what they need to keep us healthy and our brains have the neurotransmitters to keep us happy. The flax-like stem fibers have clothed our bodies in soft, durable fiber from neolithic loincloths to WWI army uniforms, even providing a dye to make them green. Nettle fiber sails transported us across oceans and nettle nets caught our fish. Not forgetting our vanity, they tone our skin, treat our dandruff, make our hair shine and some say they even make it grow. Farmers know this and feed nettles to their animals for a healthy, glowing coat. Since the dawn of recorded history and undoubtedly much earlier, our ancestors have been using nettle to treat rheumatism and rheumatoid arthritis (RA), perhaps working by the principle of “what doesn’t kill us only makes us stronger.” As if they haven’t given enough already, nettles even save some of their endowment to fertilize our soil so we can grow other crops–and raise more children.

Anything this valuable needs protection, and Mother Nature reserved her most potent weapons–formic acid and histamines–for her favorites: the nettles, ants, bees and wasps.

Stinging nettles are one of 30 species in the genus Urtica, in Latin meaning “to burn.” The specific epithet, ‘dioica,’ means two houses (di-two, oicos-house), so given because in nettles, the sexes (male and female) are produced by separate plants. For our purposes, it doesn’t matter–they both give equally.

Growing in dense, circular clumps in moist, nitrogen-rich soil, the numerous stems arise from thick, hard rhizomes, each stem attaining the height of a man, un-branched, squarish in cross-section and clothed in slender, needle-like hairs. The leaves are widely-spaced, oval, dentate on the margins, cordate at the base and likewise endowed with needle-like hairs, especially on the under-sides (abaxial surface). The flowers (either male or female) are small, greenish-yellow, and produced in loose clusters toward the top of the stem later in the season. Harvest your nettles before they’re knee-high, though. As they age, nettles accumulate calcium crystals (called cystoliths) which are not easily broken down and may irritate the digestive tract. Don’t worry though, cystoliths are not toxic and young plants don’t have them at all.

The hairs are where it gets really interesting. Each one is in reality a tiny hypodermic needle–slender, hollow cells filled with potent chemicals. Our skin is pretty amazing stuff, but no match for a nettle hair. When we brush against them, the tips easily penetrate the skin, break off, and inject formic acid and histamine underneath, provoking an immediate response–ouch! Formic acid, the very same substance used by ants, bees, wasps and a few other insects, causes inflammation, burning and intense itching, lasting from minutes to hours–or even days in sensitive individuals. Removing the sting from your nettles is as simple as rubbing them vigorously between gloved hands if eating them fresh, or washing the nettles before blanching them in simmering water.

The biochemical pathway of urtication (the sensation of being stung by nettles) is similar to the electrical signals our nerve cells use to communicate. In this case, they’re saying, “Respect the nettle, my son!”