By ROBIN ROBINSON Key West Garden Club
The Florida Keys blackbead tree (Pithecellobium keyense) is a native species of small tree that grows in the understory of hardwood hammocks and recently was removed from the threatened list. The largest one, which is located in Monroe County, is only 13 feet tall, 15 inches in circumference and has a 15-foot spread, according to the nonprofit conservation group American Forests' National Register of Big Trees.
It is wider than it is tall. Think of yourself as a small wood sprite crawling in the dark labyrinth of the branches. It would be a great adventure movie for 13-year-old boys. The branches of this small tree are dark, twisty and mysterious. The bark is dark gray with shallow fissures, just enough to hold on to as you hoist yourself into its heights.
The leaves emerge from short stems and terminate in opposite linear leaves, two or three sets of leaflets grace each stem. New leaf growth is pinkish.
The flowers are glorious pink or white 1-inch globes, each filament tipped with golden yellow. They burst into bloom throughout the year and saturate the air with fabulous aroma, drawing insects to the plant. Butterflies especially love the nectar. The Cassius blue, Florida duskywing, Florida white, giant swallowtail, great southern white, large orange sulphur, Miami blue, southern broken-dash, five different kinds of skippers and other butterflies feed on this ecologically valuable tree.
It is the larval host plant for the Cassius blue and large orange sulphur. It does its job for these butterflies, but top on the list is Tom Wilmer, Katie Lyons and Paula Cannon's discovery reported in The Citizen on Jan. 15, 2010, of a large colony of Miami blue butterflies on Boca Grande Key.
The Miami blue is a rare species that was thought to be extirpated from the Florida Keys, then it was found in Bahia Honda State Park, only to not have been seen again after the cold spell of 2010. The original population of 40 was released in areas where the butterflies were thought to thrive, such as in the Key West Tropical Forest & Botanical Gardens, but they did not do well in any of their release areas.
Cannon observed them laying eggs on the buds of the blackbead tree. In December 2009, Cannon decided to explore other offshore islands and headed for the Marquesas about 15 miles from Boca Grande Key.
"I was not there 10 minutes when I sighted my first Miami blue," she said. Cannon continued on to the Marquesas Keys and visited several other islands. She found seven islands that were home to Miami blues.
"Clearly it was the dominant butterfly species on the Marquesas islands. The Miami blue were both ovipositing (laying eggs) and nectaring on the lush pink or white flowers of the blackbead trees," she said.
If this was not enough, the blackbead tree pops a splendid thin fruit pod, 4 inches to 5 inches long. Because of the pod's narrow, curved shape, the plant has been called "monkey earrings" or "ram's horn." Inside the reddish brown pod are black seeds with a sweetish red aril. Birds go for the red aril that is attached to the ¼-inch black seed. They swallow the seed and fly off to deposit it elsewhere. If seeds are gathered directly from the tree they can be strung into necklaces or bracelets.
It provides a home for gall wasps. Blackbead can withstand short periods of flooding, drought and salt wind. It likes full sun and nutrient-poor soils with excellent drainage.
Blackbead, an undistinguished citizen of the hammock, plays a key element in nature's mysterious cycles. Plant blackbead to attract the Miami blues back to Key West. You'll get a big bang for your buck.
• The Key West Garden Club welcomes volunteers to pull weeds, learn to propagate plants and play in the sandy soil at the West Martello Tower from 9 a.m. to noon on Mondays.
Key West Garden Club Master Gardener Robin Robinson was a columnist at the Chicago Daily News and syndicated with Princeton Features. Her book, "Peeling the Onion: Reversing the Ravages of Stroke," can be found on Amazon.com. For more information go to www.sorapublishing. This column is part of a series developed by the Key West Garden Club. Visit www.keywestgardenclub.com.