Myrica comprises about fifty species of shrubs or small trees found on all continents, except Australasia and Antarctica. Most species are evergreen, their leaves covered in tiny, shield-shaped glands that give the plants a strong, resinous odour. The aromatic odour produces the scientific name of genus, which is derived from the Greek meaning perfume or scent.
The tiny flowers of Myrica species are clustered in catkins, usually with male and female catkins on separate trees. The fruits are dry or fleshy. Fleshy-fruited species, such as faya (Myrica faya), are animal dispersed, whilst the dry-fruited bog myrtle (Myrica gale) appears to be dispersed by wind and water. Fleshy-fruited Chinese bayberry (Myrica rubra) has been grown as an edible fruit from at least two millennia, and is currently commercially harvested.
Many Myrica species grow in nutrient-poor conditions, such as acid soils, where nitrogen may be a limiting factor to plant growth. Myrica species produce root nodules where the nitrogen-fixing actinobacterial genus Frankia converts atmospheric nitrogen into a form of nitrogen the plant can use. The ability to fix nitrogen means Myrica species are well-adapted to growing on low-nitrogen volcanic soils, such as those found on oceanic islands. Myrica faya, a tree native to the margins of Macaronesian laurel forests, is a serious invasive species in Hawaii. It displaces native Hawaiian trees through its ability to enrich the soil with nitrogen, and creates a nutrient-rich environment for other introduced species.
The fruits of Myrica species are coated in waxy substances made of saturated long-chain fatty acids. Most animals are poor at using such fatty acids as a food source. However, some birds, such as the North American yellow-rumped warbler (Setophaga coronata), have features of their digestive systems that mean they can make efficient use of wax as food, perhaps even enabling them to occupy more northerly latitudes in winter months compared to related species.
English parson John Lightfoot’s (1735-1788) botanical collecting expedition to Scotland in summer 1772 furnished him with raw material for his two-volume Flora Scotica (1777). In the Scottish islands and Highlands, he found people used Myrica gale as a scent, worming agent, pesticide, beer flavouring and for making candles. The Scots were not alone in using Myrica as a source of wax. Native North Americans used candleberry (Myrica cerifera), whilst Myrica wax became a plot device in Johann Wyss’ novel of shipwreck in the East Asia, Swiss family Robinson (1812).
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