ORDER XXIV. PITTOSPOREÆ.—THE PITTOSPORUM TRIBE.
The principal genera included in this order are Pittosporum, Billardiera and Sollya, all resinous shrubs, with alternate leaves without stipules, and the sepals and petals, each five in number, and laid over each other like scales in the bud. The seeds are numerous, and immersed in fibrous pulp. The commonest species of Pittosporum is P. Tobira, a native of China, easily known by its thick leathery leaves, the midribs of which are strongly marked, and whitish. The flowers are erect, and produced in cymes or heads; and the petals are united into a tube with a spreading limb. The capsule is one-celled, and two or three valved, with an imperfect dissepiment in the centre of each valve; and the seeds are numerous, and buried in a resinous fibrous pulp. The Billardieras are generally climbing shrubs, with pale greenish bell-shaped, and almost erect flowers, which are produced singly or in pairs, and which have the tips of their petals turned back. The fruit is a fleshy berry, with a shining skin of a deep blue, and it is called the Apple Berry in Australia, of which country the species are natives. This fruit is said to be eaten in Australia, but it seems difficult to imagine how this can be the case; as though the outer part of the berry is of a soft spongy nature, it is dry and insipid; and there is no internal pulp, for the seeds lie loose in the cells. In Sollya heterophylla the flowers are drooping, on long and very slender pedicels, and they are produced in cymes. The corolla is campanulate, with the tips of the petals not recurved, and the anthers are much shorter than in Billardiera. The fruit is a soft fleshy berry, divided into two cells, each containing two rows of seeds immersed in pulp, and when cut open, it smells strongly of turpentine. The plant generally called Sollya linearis has a dry and leathery pericardium; and for this reason and on account of the spreading of its anthers, it was placed by Mr. Cunningham in a new genus, which he called Cheiranthera.
ORDER XXV. FRANKENIACEÆ.—THE FRANKENIA TRIBE.
The genus Frankenia consists principally of the British weeds called Sea Heath; and the other genera included in the order are seldom seen in British gardens, from the seeds which have been imported seldom arriving in a state fit for vegetation.
ORDER XXVI.—CARYOPHYLLACEÆ—THE CARNATION TRIBE.
The plants belonging to this order have so strong a family likeness to each other as to be easily recognised; and they are all distinguished botanically by the swollen joints of their stems, and their opposite undivided leaves, which are generally connate, that is united, and sheathing the stem. The order is divided into two sections, viz.: Sileneæ, in which the sepals are united into a tube, and which section includes the genera Silene, Dianthus, Saponaria, Lychnis, and Agrostemma; and Alsineæ, in which the sepals are either quite distinct, or only slightly cohering at the base, and which includes Stellaria, Arenaria, Cerastium, Spergula, and several other British weeds. The Chickweed was called by Linnæus Alsine media, but the genus Alsine is now united to Stellaria.