Devil's Backbone

The Upside Down compound cyme (flower cluster) of The Devil's Backbone appear in February and March, in Florida.

Devil's backbone, Kalanchoe daigremontiana, is a common succulent that has naturalized across Florida. It is unique in that it self propagates, producing genetically identical progeny from the tips of its serrated leaves. It's also an increasingly problematic plant as it has escaped cultivation in multiple locations across Florida.

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Kalanchoe daigremontiana photographed under ideal growing conditions.  In Florida the plant looks a little different growing in sand and sun (below).

A wild Kalanchoe daigremontiana growing in Florida scrub.

The plant is a succulent, a native of the Fiherenana valley and Androhibolava mountains in southwest Madagascar, the Devil's Backbone has several other common names such as the Alligator Plant, the Mother of Thousands, Widow's-thrill, or the slightly misleading Mexican Hat Plant. In Florida the plant reproduces year-round and as it has escaped cultivation it has become established in multiple locations across the state, especially in South and Central Florida.

Growing in the Florida scrub Kalanchoe daigremontiana is barely noticeable most of the year.  The bloom gives away its position in February and March.

Devil's backbone is only found growing wild in Florida among the 48 contiguous states, but it's also found in Hawaii and Puerto Rico, where it is considered an invasive. The Florida Exotic Plant Pest Council has not classified it as such here (two of its cousins were added as invasives in 2017). Several groups, including the Florida Natural Area Inventory, are monitoring the plant's spread, and its potential to displace native plant species.

Devil's Backbone blooming in an invasive stand of bamboo.

It is a succulent, meaning it has thick, fleshy leaves and stems. The plant itself can hit three feet tall and has spoon-like leaves that grow along the stem either in whorls or opposite each other. It sends out above-ground roots that can enter the ground and produce new shoots. Overall, it has a shallow root system. It grows in dry places and is extremely drought tolerant.

Kalanchoe daigremontiana plantlets with tiny roots

The Devil's Backbone can reach up to 3 feet tall with opposite, fleshy oblong-lanceolate "leaves" that reach as much as 6-8 inches long and 1 1/4 inches wide. These are medium green above and, as they mature, display purple blotches underneath. As mentioned before, at the tips of the leaf serrations, are spoon-shaped bulbiferous spurs that bear young plants. These plantlets will even form roots while still on the plant.

Kalanchoe daigremontiana plantlets at the tips of leaf serrations

Adult plants can also develop lateral root structures on its main stalk, as high up as 10-15 cm from the ground. The plant has several nodes with two or three leaves on each node. The upper leaves of the plant tend to develop into disproportionately large structures, causing the main stalk to bend downwards and the lateral roots to take up root of their own, anchoring into the soil and eventually developing new primary stalks which establish themselves as indepen

Close up of Kalanchoe daigremontiana blooms in typical full-sun location in Florida, along a fence row.

Devil's backbone is a short-lived perennial, with a vegetative stage that usually lasts two years. Upon flowering the plant will die, but not before producing thousands more offspring. When Kalanchoe daigremontiana goes through a flowering season, the main stalk elongates vertically upwards by as much as a foot (30 cm), within a couple of days, developing an umbrella-like terminal inflorescence (a compound cyme) of small bell-shaped reddish-pink flowers.

It will flower, produce fruit and die. The flowers are clustered umbrella-like, pink to red, tubular and upside down. However, it flowers sporadically, sometimes not at all. A single fruit produced by one of these flowers can contain as many as 16,000 tiny seeds.

Looking up into the upside down cyme of Kalanchoe daigremontiana.

According to the Florida Natural Area Inventory, the first record of Devil's Backbone growing wild in Florida dates back to 1934. How it got here isn't stated, but most likely imported as an ornamental. That's pretty much how it has made its way around the globe. It further spreads by its wind-dispersed seeds or by improperly disposed garden waste. These days, both plants and seeds are widely available on the Internet. According to the U.S. Department of Agriculture's distribution maps, the plant is from Martin County south into the Keys. Other sources show it spreading northward along the Atlantic Coast.

Kalanchoe daigremontiana blooming in a stand of bamboo