Geiger trees are tough but versatile

Saturday, June 20, 2015

As published in the Miami Herald, 6/20/15.

Upon moving to the South, I remarked on some outstanding smallish trees with bright orange flowers. They are Geiger trees, I was told — orange Geigers. That name stuck with me, probably from growing up watching ’60s and ’70s TV where people often and inexplicably seemed to have Geiger counters at hand. But these tropical trees have nothing to do with detecting radiation.

A sprawling yellow geiger

What we call Geigers all belong to the genus Cordia. There are a good number (250-300) of them; Fairchild alone has a dozen species growing throughout the garden. Some Cordia are found naturally in India, Australia, the Middle East and tropical Africa, though most are Neotropical.

The three found most commonly in Florida landscapes are the orange Geiger (Cordia sebestena), yellow Geiger (C. lutea) and white Geiger (C. boissieri). All three share some similarities: The bark is rough, deeply furrowed, and exfoliates — it feels and looks like coarse manila rope. Their foliage consists of velvety, rather large egg-shaped leaves, begging to be stroked. Their flowers, besides differing in color, all have a crinkly crepe-paper appearance and trumpet shape, similar to some geraniums.
The pretty but harmless geiger tortoise beetle

The common name “Geiger,” legend has it, was bestowed by J.J. Audubon: While visiting his friend John Geiger in Key West, he supposedly was so impressed by the orange blossoms on a tree in Geiger’s yard — or possibly the neighbor’s yard — that he named it the Geiger tree. The problem is, Geiger built his house — now the Audubon House and Tropical Gardens — in 1846-1849. Audubon had already included orange Geiger flowers in his painting of white-crowned pigeons, circa 1832. Ah, pesky details!

Yellow geiger's intensely yellow flowers

While the orange-flowered Geiger is usually the show stealer, its origin is also in question. Some sources I found claim it is a Caribbean-Lower Keys native. Other sources, including Audubon, suggest it was introduced from Cuba into Key West through the commerce of the early 1800s.

Native or not, the stunning orange geiger 

Geigers are tolerant of salt spray, so they make nice coastal trees. All three are very drought tolerant. My own Geiger tree is the white (Cordia boissieri), native to Mexico and extreme southern Texas, where it’s called Texas white olive. White Geiger has the added benefit of more cold tolerance; mine has never shown damage from our occasional wintertime dips into the upper 30s.

Growing slowly to about 25 feet, it’s compact, but with a spreading crown. I’ve pruned mine to encourage upward, not outward, growth. Orange Geigers get a few feet taller but with similar spread.

Grow them in full sun; Geigers take even our harsh midday sun. Sandy, alkaline soil such as in South Florida is also not a problem. I watered mine as a seedling after planting, but only for a couple weeks. In about ten years, it has grown to about 10 feet and never requires irrigation or fertilizer.

Geigers may lose leaves in winter. When warm rains return, however, new foliage will appear followed by clusters of flowers, and small, spherical fruit will follow. Birds eat them to an extent, but I don’t see a lot else eating the fruit from my white Geiger.

The unscented flowers attract moths, skipper butterflies and bees. While I see denser flower clusters in the rainy season, they do flower all year long.

The Geiger seems unperturbed by scale, aphids, thrips and whiteflies. Geiger tortoise beetle larvae (Eurypepla calochroma) may feed on the foliage of orange Geiger, causing minor, temporary cosmetic damage. In ten years, I’ve seen a total of three on my (white) Geiger tree, but being on the wrong species, they apparently didn’t stay long enough to lay eggs. I wouldn’t mind seeing more; they are spectacularly beautiful metallic gold beetles.

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