Thomas Jefferson called the tree mallow the “shrub marshmallow.” In 1807, the then-president planted seeds in his Monticello nursery at the southeastern end of the vegetable garden. Dr. Antoine Gouan (1733-1821) of Montpelier had sent the seeds from France. Gouan, a botanist, introduced binary nomenclature into France; he was also the first to publish a flora that was almost totally Linnaean in its approach to classification, and he most likely had a great deal in common with Jefferson. Dr. Gouan was also known for his collections of algae taken from the waters around Marseilles — imagine what a job that would be today!
It may seem strange that a flower bearing no resemblance to the pillowy confection nonetheless bears its name, but research provides the answer. Today, marshmallows (made of cornstarch, syrup, gelatin and lots of sugar) are jammed on sticks and reduced to a blackened, burbly goo over a fire. But back in the 18th century (and before), the marsh mallow (Althaea officinalis) was something else again. The whole plant, but especially the root, contains a mild mucilage, described by contemporaries as being clammy and slimy. And the plant’s favored habitat is marshes.
Jefferson’s shrub, however, was properly called the tree mallow, or Lavatera olbia. It’s one of a genus of summer-flowering plants, once widely cultivated in European and American gardens but today, having (sadly) considerably less cachet. They originated around the Mediterranean, with a few species found in the Canary Islands and the Channel Islands off of Southern California and Baja California.
Growing plants with histories tracing back to far-off lands lends a sense of adventure to gardening. And if you could find the very plant that Jefferson grew, you’d have a garden link not only with Monticello but with the warm sands of Sardinia, not to mention its seas.
The genus was named in honor of the Lavater brothers of Zurich, 16th-century Swiss naturalists and physicians. The species is named for the city of Olbia, an ancient Roman port on the eastern shore of Sardinia.
Tree mallows made their way to English gardens in 1570, imported from southern France. They’re a branched shrub, up to 7 feet tall, with three-lobed leaves and flowers with rounded petals, usually a reddish purple.
Today, they’ve been largely replaced by another tree mallow, Lavatera arborea, a native of Southern Europe. This treelike biennial (which, if started early in the spring, will bloom the first year) has soft, velvet-to-the-touch leaves. If happily sited in full sun and well-drained soil, it’s quite capable of bearing a profusion of purple-pink flowers, their petals veined with purple, all summer long. An alternate form (var. variegata) bears white, variegated leaves.
The roots of these mallows resent disturbance, so start the seeds in early spring where you want the plants to grow, or use large peat pots for germination.
There’s also an annual tree mallow, Lavatera trimestris — a wonderful plant that can reach a height of 3 feet by summer’s end. By midsummer, the twiglike branches are covered with hollyhock-like trumpets that last until they’re cut down by frost and can take all the heat the gardener can provide.