A garden oasis and cultural center overlooking the Hudson River

Plant Hybridization in the Palm House: Case in Point

Horticultural Interpreter Alison Filosa works with Charles Day and the Public Programs Manager in Wave Hill’s Public Programs Department.

As I explored the plants in the Palm House, the central section of the Marco Polo Stufano Conservatory this past winter, I came across the stunning Pelargonium sericifolium × P. oblongatum, an unusual hybrid.the-setting

It was crossed by Ernie de Marie, a former curator of the Desert Plant collection at the New York Botanical Garden. Ernie is currently a high school science teacher, and a wonderful propagator of South African bulbs and pelargoniums. He is also, not so coincidentally, good friends with our gardener Susannah Strazzera—both members of the Hudson Valley chapter of the National Association of Rock Garden Society.

Ernie de Marie studied pelargoniums for his PhD, has a Bachelor’s Degree and PhD in Horticulture from Cornell, and remains an avid grower, raising his own plants from seed. He stores his seeds in a fridge in his basement, the locus for his hybridization activity, and then grows batches of plants as required. Once they flower, he is able to start cross-pollinating. Normally, he removes the male anthers from the flowers of a plant—to avoid autogamy (self-fertilization—and then takes pollen grains from the anthers of a second plant, transferring them to the female stigmas of the first. This type of cross-fertilization is known as geitonogamy.the-plant

A unique hybrid and a beautiful plant to behold, Pelargonium sericifolium × P. oblongatum is a combination of two pelargonium species, as its name should suggest. P. sericifolium has simple, silvery-green, wedge-shaped leaves, lending the plant a silvery appearance. The leaf color, is the result of a covering of dense silvery hairs (in botanical terms, sericeus indumentum). The name P. oblongatum refers to its oblong tuber (underground part of stem). The caudex—the swollen stem—of P. oblongatum has unusually long, hairy petioles (leaf stalks), which on most species are much shorter and along with its yellow flowers make for a fascinating contrast. In the case of this hybrid, however, it is the cerise-colored flowers of one of its parents, P. sericifolium, that have been inherited.close-up

A very rewarding choice for your garden or a sunny windowsill, Pelargonium sericifolium × P. oblongatum blooms from mid-winter to mid-spring. Come and see it before the blooms finish—not too soon, I hope! Then return on Sunday, July 8, for Wave Hill’s Scented Geranium Day, a new celebration this summer.

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