Corkwood is a common name applied to several unrelated species of trees and shrubs characterized by their exceptionally light, porous wood or thick, corky bark. The term does not refer to a single taxonomic group but rather describes a physical property shared by various plants across different families and geographical regions.
Major Species Identified as Corkwood
Leitneria floridana (Florida Corkwood)
Native to the southeastern United States, particularly in wetlands and muddy shores, Leitneria floridana is the sole species in its genus. It is notable for having the lightest wood of any tree native to North America, with a density even lower than that of commercial cork (approximately 0.21 g/cm³). Historically, the wood has been used for making floats for fishing nets and as a substitute for cork.
Duboisia species (Australian Corkwood)
Several species in the genus Duboisia (family Solanaceae), native to Australia, are commonly referred to as corkwoods. The most notable are Duboisia myoporoides and Duboisia leichhardtii. These trees have thick, corky bark and are of significant pharmacological importance. They are commercially harvested for the extraction of tropane alkaloids, such as scopolamine and hyoscyamine, which are used in the pharmaceutical industry for their anticholinergic properties.
Entelea arborescens (New Zealand Corkwood / Whau)
Native to New Zealand, Entelea arborescens is a small tree in the family Malvaceae. It is known for its extremely light wood, which was traditionally used by the Māori people for making floats for fishing nets, outriggers for canoes, and light rafts.
Erythrina species (Coral Trees)
Certain species within the genus Erythrina, such as Erythrina vespertilio (Grey Corkwood) and Erythrina herbacea, are sometimes called corkwood due to their light, spongy wood or the texture of their bark.
Characteristics and Uses
While the botanical families differ, "corkwood" species typically share several characteristics:
- Low Density: The wood contains large, air-filled cells, making it highly buoyant and easy to carve.
- Insulation: The thick, spongy bark found on many corkwood species serves as an evolutionary adaptation to protect the tree from fire or extreme temperatures.
- Economic Utility: Beyond pharmacological uses in the case of Duboisia, corkwoods have historically been utilized in the production of bottle stoppers, life preservers, and insulation materials, though many of these functions have been superseded by synthetic materials or commercial cork from the cork oak (Quercus suber).
Regional Variations
In various parts of the world, other plants may locally be called corkwood, including members of the genera Commiphora, Pisonia, and Sesbania, depending on the local prominence of the species and the physical characteristics of its timber or bark.