Nature’s version of honey mustard
THE nasturtium isn’t native to California, but it has adapted so well, it’s time we took out adoption papers. It has the poppy’s quirky mix of toughness and grace. It’s got a bewitching fragrance and a “Wizard of Oz” color scheme. The flowers run from cream to scarlet, the leaves from emerald green to lime to variegated. Some flop, others climb, but all are somehow touchingly comical. Best of all, it’s delicious.
Ah, and indecently vigorous. Nasturtiums only look delicate. They will grow faster than you and the slugs eat them. They appear after winter rains in even the most marginal soils. The shield-like leaves that give them their botanical name, Tropaeolum majus, make them superb ground cover and help conserve water. But underneath the soil line, they do not sprout fierce root systems.
In Southern California’s temperate zones, they bloom from late winter until early summer, after which they burn off only to reappear after the first winter rains. If you planted nasturtiums in the past, you’ve probably got some seedlings appearing right now. They are good self-seeders. If you didn’t, now is the time to invest in a packet of seeds. Few flowers are easier to grow, no flower is more gratifying. Just push the caper-sized seeds an inch under the soil, and let it rain. Easier than a Chia Pet.
Books say that they tend to attract aphids, so evidently some kitchen gardeners use them as insect bait near their vegetable patches. To my mind, they look loveliest planted at the base of larger shrubs, along garden paths. By early spring, they will be spilling over walkways like something out of a Monet painting.
Pleasing to the senses
For all their beauty, their most profound charm is scent. As dew burns off in midmorning sun, they smell like honey and spice. If the family dog gets in the nasturtiums, you’ll know. It will come back smelling like a meadow. But as the realization dawns that your smiling beast has been trampling the flower bed, don’t worry. The next day the nasturtiums will have recovered and the flowers lining the path will be frilly, voluptuous and again emitting that smell.
What’s behind it? Much the same thing behind the flavor, it seems. Nasturtium leaves have alkaloids similar to those found in mustard, arugula or watercress. The leaves are also edible, and when young and tender so good that one of their alternate names is “Indian cress.”
The nasturtium’s dominant alkaloid is called benzyl isothiocyanate, a compound with strong medicinal properties. Because of that, says Robert J. Griesbach, a research geneticist in the Beltsville offices of the U.S. National Arboretum, you shouldn’t eat loads of them. Remember, they’re a garnish and not a salad leaf. Griesbach also warns against eating flowers bought from garden centers or florists, which will probably have been treated with pesticides.
James Duke, a botanist employed for many years by the Agricultural Research Service, studied the plant for the U.S. government as a potential cancer medicine. He is now continuing the study at his Green Farmacy Garden in Fulton, Maryland. This positive oracle can give you the name in dozens of languages (The Dutch name is “Oost-Indische Kers” and Spanish one “Taco de Reina.”) Ask its chemical content, and he’ll respond with a list of more than 70 compounds, from antheraxanthin to water.
But what about that honeyed smell on the dog?
“It’s the nectar,” says Warren Roberts, director of the UC Davis Arboretum. “It’s in the flowers, but not the leaves. Nasturtium flowers are pollinated by hummingbirds. There is nectar in the spurs. So if you eat the flower, you get some nectar as well as the spiciness of the petals.”
Nasturtium flowers, Roberts explains, are still peppery, but milder-tasting than the leaves, nature’s version of the perfect honey-mustard dressing. Roberts once lived in the Andes, where nasturtiums are native. There he’s seen them climb up cornstalks in mountain fields and thick tubered varieties sold as vegetables in food markets.
But here, outside batty food fads in which flowers are suddenly fried, candied, brined and tossed into everything from the cocktail to the sorbet, all for one dizzyingly floral meal, we don’t eat garden flowers much. In the case of the nasturtium, Roberts guesses that this is because it came to us, via Europe, as an ornamental. The fact that the pretty flower was also a food got lost in translation.
The fresher, the better
In the case of the nasturtium, it was also never commercialized as a food because it is so perishable. The best way to eat the flowers is straight from one’s garden, so you know no pesticides have been used and the flower is fresh and fragrant. Washing will damage them. Just pick high, bright, clean specimens. It’s hard to beat tossing them in a salad for bright peppery-sweet notes. They can function wherever arugula or watercress would, except more brightly. They’re great garnishes for cream cheese, meat or pasta, provided people can bring themselves to give them the coup de grace. Rosalind Creasy, the Bay Area garden writer, dices them like a herb and uses them like, say, chopped chives.
One of the nicest ways Roberts has seen nasturtium flowers served was in England, in a watercress-style sandwich. This is a particularly English good idea, involving perfect white bread, cut in triangles with the crust trimmed, and the bread itself generously spread with salty butter, then the flower sandwiched between two pieces. Of course, it demands a perfect cup of tea.
The lesson from Roberts: A plant’s beauty isn’t necessarily how it looks -- it’s how it tastes. We’d eat nasturtiums more often here, he thinks, “if our tongues had eyes.”
