Scouring the grounds in search of different mustards


Regular readers of this column are already familiar with the EcoFlora Project run by the New York Botanical Garden. This project is trying to compile a complete list of plants — cultivated and wild — growing within New York City.

Such an ambitious project is only possible by involving as many members of the public as possible through the iNaturalist app, to report sightings of plants growing locally. May was designated “Must Find Mustard” Month, and it was an eye-opener.

My initial assumption was that the only plant sought was the infamous garlic mustard Alliaria petiolata, infamous because of its invasiveness. While the project is primarily interested in the wildflower branch, these mustards are part of the larger Brassicaceae family, which shows up on the dinner table as broccoli, cabbage, and Brussels sprouts, to name a few common members.

However, the botanical garden provided a sheet with other Brassicaceae members that we would be likely to encounter. And I found several surprises among them.

The first was woad — Isatis tinctoria — the plant which generated an indigo dye that was purportedly used by the Picts to decorate their bodies before battle. This piece of information was based on limited translations from the Latin records of Julius Caesar and others.

Modern efforts to create a body paint derived from woad have not been able to reproduce anything that was easy to use or long-lasting on the skin. The Tuareg are a nomadic Berber-speaking group of northern and northwestern Africa. They are also known as the “blue people” since their clothing is dyed blue with indigo and frequently stains the skin blue as well.

Perhaps, the woad dye likewise stained the skin of the English tribes.

Indigo can be extracted from several different plants. Woad was used in Europe until the indigo extracted from Indigofera tinctoria (a Fabaceae family member), replaced it once a direct trade route between Europe and India was established in the late 15th century by the Portuguese explorer Vasco da Gama.

Woad’s flowers are yellow, but the blue dye is extracted from the leaves. It is native to the steppe and desert areas from the Caucasus to Siberia.

Indigofera tinctoria grows in more tropical and temperate areas of Asia and became so widespread that its precise native locale is not known. The flowers on this plant are a fuchsia, and again, the dye is extracted from the leaves.

India was a prime supplier of indigo (from Indigofera) already during the Greek-Roman period. This is enshrined in the name itself as indigo is derived from the Greek indikon meaning “Indian.” The chemical structure of the dyes from both plants is identical.

I was also surprised to see the annual fragrant sweet alyssum (Lobularia maritima). Most of the mustards have a pungent odor, and alyssum on a warm day smells like honey. While the flowers come in shades of pink, rose, lavender purple and apricot as well as white, it is my experience that the white-flowered plants have the heaviest scent.

Considered easy to grow, it is used as an edging plant because it is low-growing, forming a mat between three and nine inches high. Apparently it is common on beaches and dunes, which explains the maritime epithet meaning “of the sea,” or coastal.

Lobularia comes from the Greek meaning “small pod,” and refers to the shape of the fruits seen on the tip of the branches after the flowers fall off.

Another edging flower used in gardens that was on the list is the perennial Iberis sempervirens, colloquially known as candytuft. It is a bit taller than the alyssum, and its flowers — which only come in white — bloom in the spring.

Although, both alyssum and Iberis have four-petalled flowers, they seem readily distinguishable to my eye with the Iberis appearing fuller.

Iberis is native to southern Europe. Its scientific name reinforces that point since Iberis in Greek means “from Iberia,” the Iberian Peninsula encompassing the southern European countries of Spain and Portugal.

The sempervirens epithet indicates that the plant is an evergreen, where semper means “always” and virens means “green.” However, it is only evergreen in warmer winter climates, and is considered semi-evergreen in harsher environments.

The last surprise on the list were the two wildflower — Honesty plants, Lunaria rediviva (perennial) and Lunaria annua (biennial).

The Lunaria annua have taken up residence in my garden and are one of my spring favorites. Once again the flowers are four-petalled, with the perennial flower color being white with purplish overtones, and the biennial being a lovely shade of lavender.

In addition to the beautiful flowers, the seed pod is special and is often seen in dried flower arrangement. The seed pod elongates into a round (biennial) or ovaloid (perennial) structure, which is initially green and then becomes silvery and translucent so that the individual seeds inside are clearly visible.


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