This family as originally understood is a very large one, and plants belonging to it are found in most parts of the world. The species are varied in detail, just as its distribution is worldwide, and many are far from the form we commonly associate with a Heath.
In the early part of last century Robert Brown noted that there was one feature whch enabled the family to be divided into two natural groups. In one the anther maintained separate pollen chambers, and in most instances dispersed the pollen through pores; in the other the chambers coalesced to form one, and on maturity split along its whole length. The first group is the Ericaceae, having the genus Erica for its type. It also includes the unheath-like Kalmia, Azalia, Waxberry, and Rhododendron. The second group having our common Heath, Epac-ris, for its type, is called Epacridaceae, and includes also our mountain Grasstrees. The Erica family is very widely distributed; we have four species, of which Waxberry is the commonest. But its principal home is Europe, North America, and South Africa. The Epacris family is much more restricted, being almost confined to Australia and New Zealand, a few species only crossing the Southern Pacific.
This latter family, which may be called the Australian Heaths, is the subject of the present chapter. It is a large group, and very common throughout Australia. They are all shrubby in habit. Though some are small, they are not of the succulent, temporary character we associate with the name herb, and though others are tall, they do not assume the proportion of trees. These three names, herb, shrub, tree, are popular names incapable of accurate definition, but they are too useful to be dispensed with. Another feature of interest is that the leaves have always a simple outline; that is, they are never lobed or divided into leaflets, and they are generally narrow, with parallel veins, and of thick consistency. This constricted form and thick structure is very suited to the dry sunny condition of the Australian climate, and will be again referred to.
Our common Heath is one of the most beautiful wild flowers. Though numerous, the flowers are arranged singly along the branches; each is placed in the axil of a leaf. The axil of a leaf is the upper angle between a leaf and stem or branch. This single arrangement is one of the marks by which the genus Epacris may be known, but is not peculiar to the whole family. The stalk of the flower is short, and is clothed with much reduced leaves. Leaves on the flower stalk when changed to assist the flower are called bracts. The calyx consists of five bractlike sepals, which are free from one another and clothe the base of the flower. The corolla is composed of five petals, which are united for the greater part of their length into a tube, the five ends are free and spreading. The tube varies greatly in length in different individuals. The corolla is delicate, and of all shades, from white to dark-crimson. It appears to attract insects, and consequently forms good seed, irrespective of the tint. Therefore the colour of the flower and length of the tube, like many other details in plants, may be considered as accidental circumstances and not accurate adaptations. The corolla arises from the thalamus close above the calyx.
The stamens are five in number, and instead of arising as in Ranunculus, they come off from the corolla near the top of its tube. This is not universal in the family. In some genera they arise from the thalamus. The anthers are small, and the single pollen chamber opens along its entire length. The pistil of Heath is very different to what we have seen in Buttercup. Instead of a collection of little free carpels, it appears in a single body in the centre of the flower. It has a spherical part below, and a long, slender, simple style, ending in a little round stigma shaped like the head of a pin. The spherical base of the pistil has not a smooth surface; the top where the style comes off is much sunk, so that it appears to arise from the bottom of a pit, and the surface is marked by five shallow erect depressions. If you cut through the body at its broadest part it will be observed that it is made up of five small cavities, and the depressions mark their boundaries. Each cavity is an ovary, and at its inner angle arise many minute ovules. The pistil of a Heath is therefore made up of five blended carpels, which is apparent is the ovarian portion, but quite obscured in style and stigma.
When the flower withers the fruit is formed. This is not much changed in character. The compound ovary becomes rather larger, and dries. It then bursts along the back of each carpel, to allow the minute seeds to escape. Such a fruit is called a capsule.
Our mountain Grasstrees belong to the genus Richea, and it is a pity, where the scientific name is so easy, it is not more universally used. This is all the more desirable in such a case as the present, for the name Grasstree is also given to a very different group of plants, which are also called Blackboy, that belong at the junction of the Lilies and Rushes. Blackboys have very numerous long wiry leaves, arising from the top of the stem, and a long erect central club upon which numerous small flowers are borne.
Richeas are very unheathlike in general appearance, but the flowers are of the Epacris type. The leaves are relatively broad, and in some cases very long; they always arise from a broad base closely enveloping the stem, which they mark by a circular ring. The flowers are numerous and clustered in bunches towards the end of the stem, each bunch arising in a leaf axil. The corolla is closed above, or has microscopic lobes, and at maturity falls of entire, looking somewhat like a grain of rice. From this, Richeas are sometimes called Rice plants. The stamens do not arise from the corolla, but are inserted into the thalamus, so that when the corolla falls the anthers and stigma are exposed to the visit of insects. The flower does not otherwise differ from the type described above.