regnum-plantae:

Casuarina equisetifolia, Casuarinaceae

Second in the series of native and introduced plants of Lanzarote comes the Australian pine tree, which I hadn’t seen in probably ten years -since the last time I was in southern Italy- and that I found to be extensively used in the landscaping of the area I visited. After a first, quick look, the tree could indeed be taken for an exotic looking pine (Pinus), but despite the name and similarities Casuarinas are actually Angiosperms! Native to SE Asia, Australia and New Zealand, it is generally found in semi-arid situations, in well-draining, alkaline soils and often on sand dunes and beaches. Aside from being the reason why it is so successful on the seashores of Lanzarote, this resilience is also what gave the tree the characteristic conifer-like look. Green, thin and deciduous twigs perform the role of leaves and are peculiar in their segmentation reminiscent of horsetail (Equisetum), after which the species is named. This kind of structure is an adaptation to perform photosynthesis more efficiently in dry, windy and sunny conditions than a broad leaf might be able to. Like conifers, the tree is wind-pollinated, but the dry, woody structures it produces are not cones, they’re fruits. As they open, they release tiny winged seeds, quite easy to miss unless they fall in your cup (ahah!). If given the chance in the right place, the Australian pine tree can be rather invasive and smother native vegetation by shedding a thick layer of twigs -much like it happens in conifer forests- which also hinder germination with allelopathic biochemicals.

If managed well, the tree can also do the opposite, and aid crop plants and smaller fruit trees: like species within the Fabaceae, it can fix nitrogen in the soil through the association with bacteria while it provides dappled shade when the sun radiation is too intense and acts as windbreak against drying hot air. In its native area it has been used as a medicinal plant to treat skin imperfections and gastrointestinal problems, but also as a tanning agent and widely as high-quality fire wood.