THE HERB AGE is the official journal of the Herb Society of Victoria. It is published every month except January and sent by post to every member.

 

One of the main contributors to The Herb Age is Colline Muir. Colline’s articles are always well researched, always informative and often quirky.

 

Here’s Colline’s recent article on ‘Who’s Related and Why?’.

 

What have sunflowers and fleabane got in common? What about parsley and hemlock, or lavender and mint bushes, or wattle and goat’s rue?

 

Most of us know that plants have at least two botanical names. The first, such as Salvia, is the generic name, spelt with a capital letter, and this is followed by a specific name, such as officinalis, spelt with a small letter. These two names belong to sage, and to no other plant. They are rather like a surname and a Christian name and together they form the species name.

 

Each of the pairs of plants named in the first paragraph is classified into a particular plant family because it has certain features in common. These common characteristics are mainly found in the arrangement of the reproductive organs but also in the arrangement of leaves and other characteristics. Now all families take their names from a typical genus belonging to that family, for instance MYRTACEAE, after the genus Myrtus, and all family names end in ‘EAE’.

 

A few years ago, the international plant naming body decided to bring all plant family names into line. Some well known names were changed, for instance, COMPOSITAE (ending in AE) was changed to ASTERACEAE after the daisy genus Aster. Many of our best known herbs belong to this family.

 

Some herbs in this family are sunflower, yarrow, tansy, lavender cotton, curry plant, dandelion and artichoke. The name COMPOSITAE was usefully descriptive. If we look closely at a sunflower, we will see that it is not just one flower but a composite made up of many tiny florets, crowded together in one head. Each floret has a pistil and stamens and produces one seed. They have no petals. However the ray florets around the outside are specialised for display, sacrificing their reproductive ability, uniting their petals into one big advertising banner. All these florets are united into one head, surrounded by small modified leaves or bracts.

 

What about fleabane? The flowers are insignificant, without any colourful display, yet it reproduces all too successfully. If we examine a fleabane flower head, we find a few tiny florets surrounded by bracts, the same composite structure as a sunflower but without ray florets. Lack of ray florets saves energy but the plant must have something else up its sleeve to attract pollinating insects. Perhaps it has a scent that insects can detect. The family includes trees, shrubs and annuals.

 

What do parsley and hemlock have in common? And carrots, parsnips, coriander, alexanders, angelica and Centella? These plants all produce their flowers in an umbrella-shaped inflorescence called an umbel, hence the former family name UMBELLIFERAE. However, the family is now known as APEACEAE, a typical genus being Apium, which includes the herb smallage. Many plants of this family are herbaceous, often biennial. Flowers are usually star-like with five pointed petals, five stamens and a two-chambered ovary, often becoming dry and compressed. Those of tree angelica for instance hang down on slender stalks, while those of parsley stand up.

 

Small insects love these umbels, as they can walk over a carpet of tiny flowers sipping nectar and gathering pollen from each one as they go. Ladybirds like them, as they are fond of the protein-rich pollen. Hard cheese too, I imagine, for any misguided aphids that come their way.

 

Members of this family are mostly herbs, their leaves arranged spirally. In Australia there are some surprisingly atypical representatives such as flannel flowers, which superficially look more like composites.

 

Probably the most herby family of all is what was known as the LABIATAE, (from labium, a lip) because the flowers have two lips, top and bottom, and are easily recognised by this feature. Now, however, the family is known as LAMIACEAE, from the genus Lamium, the dead nettle. To this family belong the salvias, lavenders, rosemary, mints, mint bushes, Erimophylla, Prostanthera and many others. They are characterised by square stems, opposite, often aromatic leaves, their two-lipped flowers and fruits containing four little nutlets. The corolla is fused into a tube, with the lips free at the end. The flowers are often crowded together in whorls at the apex, such as lavender, or extending down the stem in the axils, such as mints, or they may be in axillary pairs or singly as in rosemary and salvias.

 

What about wattle and goat’s rue? They both produce their seeds in pods and were therefore all included in the family LEGUMINOSAE (legume, a pea), but this has now been divided into the MIMOSEAE with flowers in fluffy heads like mimosa, and FABACEAE, those with pea-shaped flowers like the genus Faba, the broad bean.

 

Sometimes relationships are not so obvious, as with lemon trees and boronia, which both belong to the family RUTACEAE, named after Ruta graveolens, rue. The family includes trees (such as the Australian Flindersia of the outback) and shrubs such as Eriostemon and Correa. One characteristic which most family members have in common is glandular, fragrant leaves.

 

If you find plant classification confusing, it can be helpful to find out which family a plant belongs to, what its relatives are and what they have in common, to put it into some sort of context. It can be more fun than a jigsaw!

 

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