Monday, May 27, 2024

Wild Allamanda (Hammock Viper's Tail) - Pentalinon luteum

Wild allamanda (Pentalinon luteum) is a perennial evergreen woody vine native to the southern coastal counties of Florida - from Lee County on the west coast to St. Lucie County on the west.  It also is found throughout much of the Caribbean and on the Bay Islands of Honduras.  Although it is semi-tropical to tropical in nature, it has some cold tolerance and has been used ornamentally in landscapes that periodically receive light freezing temperatures. It naturally occurs in a variety of soils in hammocks, pinelands and coastal thickets although it has only limited tolerance of light salt spray. It prefers full sun in all of these habitat conditions.

Like most vines, wild allamanda clambers naturally through adjacent vegetation and can get extensive in a landscape if not occasionally pruned back or trained to climb a trellis or pergola.  It has attractive oval shiny leaves that are opposite on the stems and curl slightly under along the margins - which are entire.  Each leaf is 1-3 inches long and up to 1 inch wide.  The stems are decidedly woody and are numerous arising from the central root.  Because of this, frequent/regular pruning can make it become shrublike.  

Flowering occurs in most months, but mainly throughout April - September in Florida.  The trumpet-shaped bright yellow flowers are 2 inches long and composed of five fused petals.  They are produced in clusters at each of the branch tips and normally open one flower at a time in sequence.  The flowers are especially attractive to large-bodied bees and the pollinated flowers ripen into a 2-parted pod. 

The foliage and flowers of this beautiful wildflower are toxic if eaten and will cause nausea in mild cases, but more severe reactions in more-sensitive people.  The sap can cause skin irritations so care must be taken when pruning it.  Wild allamanda is a relative of the extremely toxic, but widely planted, oleander, and serves as a host for the oleander moth. 

Although care should be taken when considering adding this native vine to your landscape, its beauty and adaptability make it a good choice in locations where it is not likely to be handled by curious children or eaten by pets.  Wild allamanda should not be confused with the more commonly planted landscape allamandas in the genus Allamanda, but all share the same level of toxicity.