(Casuarina equisitifolia, C. glauca, C. cunninghamiana)
caz-you-RINE-ah (alternatively in some places caz-you-REEN-ah)

Perhaps other plant enthusiasts share my lazy tendency dismiss invasive exotics as nasty, and then give them little further thought. But such blinders obscure much of our green environment.


Branches with "cones" (by John Bradford)


Today’s tree is Australian-pine, species of Casuarina, mainly Casuarina equisetifolia around here. The name Australian-pine is a misnomer. The trees are not related to pines and are not altogether Australian. Beyond Australia, Casuarina equisitifolia lives naturally (?) in Southeast Asia and on some Pacific islands. Ancient peoples in boats probably moved them around, and the tiny wafer fruits cross water on the wind.
The Australian-pine introduction to formal botany dates to the 17th century blind botanical genius George Rumphius on the Indonesian island of Amboina. Rumphius referred to the tree as casuaris-boom, reflecting resemblance between patterns in the wood and plumage of the weird cassowary bird.

Casuarina at Jupiter Inlet


No need to devote much space to the tree as an invasive exotic. It is a severe one, forming blanket monocultures to the exclusion of all else. There’s oodles elsewhere on the Internet.

The tree has been a Floridian since at least as far back as 1887, bringing to mind the Reasoner Brothers historic Royal Palm Nursery established near Bradenton in 1881, although I’m not really sure they sold it. In either case, Casuarina had been in the West Indies well before the 19th Century, and as already mentioned, the wafer fruits flutter freely over the bounding main. Coming to Florida was inevitable, and it may have occurred repeatedly.

Casuarinas do look like pine trees, and some 19th century botanists interpreted them as a missing link between the conifers and the flowering plants. They are 100% flowering plants having no relationship to pines. How experts mistakenly allied our trees with conifers is puzzling as it doesn’t take much examination to peg the similarities as superficial, not even involving the same parts.
Just like a true pine tree, an Australian-pine can thrive in nasty harsh environment, such as Florida beaches and dunes. Contributing to their ability to invade (or shade, depending on your perspective) are nitrogen-fixing root nodules, something we more famously associate with legumes.

Divergent perspectives sure do cloud issues. There is no question at all that the species is an eco-menace. But here it is, and where I used to live in the Caribbean, Casuarinas were prized shade and beach trees, and I used to enjoy beer, fries, and silvery sands at the shady Casuarina Beach Resort.

A species able to grow ten feet a year in a salty sandbox deserves attention from additional angles. Florida botanist Julia Morton thought they were good barbecue fuel, and the abundant trees are a guilt-free source of mulch wood chips, although the chips reportedly inhibit the growth of other plants. (I have used them with no obvious trouble.) The world abounds in inferior salty soil, limited water, and the need for wood and green coverage. The trees tolerate mine tailings and stabilize shifting sand. In India Casuarina plantations yield fuel after only 5-7 years, and the hard fine-grained wood supplies rough construction, tool handles, ores, and docks.

Gremlins like to post signs above copy machines urging staff to save the forest by restraint with copier paper. Well sure, I’m all for saving the forest and the office budget. So here’s a related thought: maybe a commercial source of paper pulp where nothing else grows might save a tree.



Casuarina "cone"

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George Rogers

About George Rogers

George Rogers is the Chair of the Horticulture Program at Palm Beach State College in Palm Beach Gardens.