Hakea is, from the shape of its fruit, often called Native Pear, but as this name is also given to two or three other shrubs we may be excused for dropping it in this instance. We have no less than seven members of this genus. One which does not occur south of Bass Straits has narrow but flat leaves, but the rest have all similar foliage, namely slender cylindric needles, assuming somewhat the appear ance of a Pine. Our common Hakea is a rather large shrub. The flowers are small, white; and arranged in little axillary clusters. Though small they are structured just as in Waratah. One difference may be noted, and this is found in many genera of the family: they are arranged in pairs; that is, however dense the cluster, it is made up of pairs of flowers. The fruit is very different from that of any other shrub we shall meet with; it is a wooden ball about an inch in diameter. When ripe it splits in two, exposing two flat black seeds that have well-developed thin wings on one side.
Small-fruited Hakea grows in marshy places. It is a smaller shrub and the fruit, which is about half an inch in diameter, is not so woody. Dagger-fruited Hakea is less common. The leaves are rigid and sharp, and the fruit is dagger-shaped. Another form has a small fruit sharply curved at the base. The two remaining species are rare, and appear only to have been gathered on the North-East Coast. Many of the Hakeas of Australia have broad leaves. This genus is very close to the large Australian group of Grevillea, which differs in little except the fruit being leathery instead of woody. We have but one Grevillea, a small mountain plant. Orites is with us a much more common mountain genus, but it has straight flowers instead of much curved, as in our Grevillea.
Honeysuckle is a very common tree. The leaves are variable in shape, narrow or broad, toothed or plain on the margin; the end appears as if cut off abruptly, and the under-surface is nearly white and closely netted by the veins. The toothed leaves are generally only found on very young specimens. The flowers are massed together in dense, oblong cones; as in Hakea and Grevillea they are arranged in pairs in the cones. The styles are very long, forming conspicuous objects in the flowering stage, otherwise they do not differ from the form described. The fruit is a rather large flat, almost woody capsule, which on splitting exposes two winged seeds. A few of these fruits may generally be seen on most old cones. We have only one common Honeysuckle, but there is a second whose leaves are always serrated, and whose cones are very large, that occupies a small area near Table Cape.
We have a few other most interesting members of this family. Mountain Rocket is common on elevated plains. It is generally a very small shrub with numerous pink and white little flowers in a head on the end of an erect stalk. The fruit is flat, bright-red, and soft. Native Plum is confined to the west. It is very like Laurel, only the leaves are larger, flowers inconspicuous, fruit a small purple plum. Persoonia is a small bush with small spiney leaves, yellow flowers, and fleshy fruit.
When we speak of the migration of Australian and African Proteas from a common northern source we convey an idea of simplicity probably not at all in accordance with the true state of affairs. There has not been a constant advance in even general climatic conditions on the surface of the globe, but a complicated oscillation of general and local changes, which have left but few signs of their existence behind them. We have evidence that in comparatively recent times a luxuriant vegetation existed even in polar regions, followed by arctic conditions extending towards the tropics. The same alternations seem to have occurred right back in very early times. The luxuriant vegetation of the Carboniferous era was succeeded by the frigid conditions of the Permian. What number of such cycles have filled the space between, and what have been the causes, we have only the vaguest notion. Another factor of plant-distribution, the oscillation between land and sea, giving freedom of migration at one time with close isolation at another, we have but scanty information of. A third change that must have largely influenced plant life, condition of atmosphere, is almost a closed book. There is one thing certain - the present constitution of the atmosphere, however agreeable to us, is far from the best for plant life. There are at present on the average but three and a half parts of carbonic acid in ten thousand parts of air, yet plants do best when this gas is present to an extent even exceeding four parts in a hundred, or more than a hundred times as much of this gas. The presence of a larger proportion of this gas than at present obtains would not only afford more food for the plants, but would much modify climatic conditions, rendering it warmer and more equitable. It is probable that atmospheric conditions, distribution of land and sea, together with large cycles due to other causes, have caused oscillations of climate of which we can form but the slightest conception. Thus the evolution and distribution of plants is a far more profound problem than it is generally considered.
Mountain Rocket. (Bellendena mondana, R. Br.) [See p. 78
Dagger Hakea. (Hakea pugioniformis, Cav.) [See p. 76