About Pilosocereus robinii (Lem.) Byles & G.D.Rowley
Pilosocereus robinii is a large, erect cactus that often grows many parallel or spreading branches. It can reach the size of a tree up to 10 m (33 ft) tall. Stems are green with a blue tinge when young, and bear 9 to 13 ribs. Areoles are covered in hairs of varying length, and hold up to 31 spines each; all spines measure no more than one centimeter long. This species produces bell-shaped flowers 5–6 cm (2.0–2.4 in) long. Outer tepals are greenish with brownish mid-stripes, while inner tepals are white. The flowers have a garlic-like scent, open at night, and contain sweet nectar. Pilosocereus robinii is native to northern Bahamas (from Andros and Cat Island north to Abaco), northwestern Cuba (provinces of La Habana, Matanzas, and Mayabeque), and the Florida Keys of the United States; it is the only Pilosocereus species native to the United States. In the Florida Keys, this cactus grows in upland tropical hardwood hammocks on limestone or coral substrates. It can sometimes be found growing on sparsely vegetated coral rock, located just above the high tide mark. Few individuals of this species produce fruits. Its seeds are dispersed by frugivores, and windy conditions also spread seeds. Wind can also break off branches that are capable of rooting on their own in soil. Storm surges and sea level rise may inundate this cactus's shoreline habitat, raising salinity to levels beyond what Pilosocereus robinii can tolerate.
