This rare Caribbean shrub or small tree is Cock’s Spur, Erythrina eggersii. It belongs to the legume family, Fabaceae, and is found naturally only in Puerto Rico and the Virgin Islands. That very limited range makes it an especially important part of our regional plant heritage.

Cock’s Spur may grow to about 20 feet tall, although some plants remain more shrubby. Its trunk, branches and even parts of the leaves can carry stout, conical prickles. Those sharp projections help explain the common name, because they resemble the spur on the leg of a rooster.

The leaves are divided into three leaflets, a common feature among coral trees. During a pronounced dry period, the plant may lose much of its foliage, leaving the thorny framework of the branches clearly visible.

The flowers are the most dramatic feature. They are large, elongated and usually bright red or scarlet, with the distinctive pea-flower structure of the legume family. They often appear in clusters near the ends of the branches and may be especially noticeable when the tree has few leaves.

Their vivid color and tubular form are well suited to visits from hummingbirds and other nectar-feeding birds. As the birds move among the flowers, they can carry pollen from one blossom to another.

After flowering, the tree develops long legume pods. As the pods mature, they dry and split open, revealing hard seeds. Like the seeds of many Erythrina species, they should be regarded as ornamental rather than edible.

The scientific name honors Henrik Franz Alexander von Eggers, a nineteenth-century botanist who studied the flora of the Danish West Indies and collected extensively in the Caribbean.

Cock’s Spur is now considered endangered, largely because so few wild plants remain and because its habitat has been reduced or disturbed. Conservation organizations report that fewer than 75 individuals may remain in the wild.

That makes a cultivated specimen especially valuable. It is not simply an attractive red-flowering tree; it is a living representative of a species whose entire natural world is confined to Puerto Rico and the Virgin Islands.

Its sharp prickles, three-part leaves and brilliant coral-red flowers make it memorable, but its rarity is the most important feature of all.