The eucalyptus and myrtle family
Myrtaceae puts more greenery into a florist's cooler than any other family, and it puts the clove in the mulled wine and the guava in the fruit bowl as well. It is a family of aromatic woody plants assembled almost entirely in the southern hemisphere.
around 140 genera
somewhere near 6,000 species
The southern hemisphere, overwhelmingly Australia, with a second center in tropical America
Everything in this guide that belongs to Myrtaceae
The test for this family takes a second and works on every member of it. Take a leaf, hold it against a window or a lamp and look through it. Scattered through the tissue are hundreds of translucent dots, like pinpricks of light coming through. Those are oil glands, cavities in the leaf filled with the volatile compounds that make a eucalyptus smell of eucalyptus.
Crushing a leaf breaks them open, which is why the scent arrives when foliage is handled and why this family gives the world eucalyptus oil, tea tree oil, cajuput and clove oil. The leaves themselves are usually simple, untoothed and leathery, and in most of the family they are held in opposite pairs.
The same glands are why this family fills a spice rack. A clove is the dried unopened flower bud of a Myrtaceae tree and allspice is the dried fruit of another, while guava, feijoa and the lilly pillies are all in here too.
Most of this family gave up on petals. What you see in a bottlebrush, a melaleuca or a eucalyptus blossom is a dense burst of stamens, dozens or hundreds of long filaments each tipped with pollen, while the petals are reduced to something negligible or dropped altogether. In eucalyptus the petals and sepals are fused into a lid that is pushed off whole as the flower opens, and that lid is what named the genus, from the Greek for well covered.
Waxflower is the member that still behaves like an ordinary flower. It keeps five spreading petals with a thick cuticle, which is where the name comes from, and the wax is functional rather than decorative: it slows water loss in a plant native to dry sandplain country in Western Australia. A structure built to hold water through a drought holds it in a vase as well, and that is most of the reason waxflower lasts the way it does.
A eucalyptus changes shape as it grows up, and the difference is large enough that the two forms were once described as separate species. Juvenile foliage is round or heart shaped, sits tight against the stem in opposite pairs and carries the heaviest silver bloom. Adult foliage is long, narrow and sickle shaped, arranged alternately and hanging vertically, so a mature tree casts almost no shade.
The silver dollar and baby blue bunches sold as foliage are juvenile growth, kept juvenile by cutting the plant hard every year so it never matures. Seeded eucalyptus, with its clusters of small woody capsules, is the adult stage of a different species. They are not interchangeable in an arrangement and they are not the same price.
This family is bought for its longevity. Eucalyptus holds two to three weeks fresh and then dries in place rather than collapsing, and waxflower will outlast nearly everything standing next to it. Neither wants deep water, and eucalyptus in particular fouls a vase quickly if the lower leaves are left submerged.
The first caution is ethylene. Waxflower is unusually sensitive to it and answers by dropping its flowers off a stem that still looks perfect, so keep it away from ripening fruit and out of any room where something is going over. Growers treat it before shipping and it is worth asking whether yours has been.
The second is skin. The oils in waxflower foliage cause contact dermatitis in a proportion of the people who handle it all day, and eucalyptus oil is toxic to cats and dogs if the foliage is chewed. Neither is a reason to stop selling either one, and both are worth saying out loud.