The Barbary Box-thorn, or Duke of Argyle’s Tea-tree, (Lycium barbarum) has a somewhat rotate corolla, with a five-cleft limb, with the stamens inserted between the segments in the same manner as shown in the flower of the Atropa Belladonna, represented cut open at b in fig. 69. The filaments are hairy at the base, and the anthers are near together, but do not form a cone as in Solanum. The berry is two-celled, and the calyx remains on when it is ripe, as in all the other genera of this order. There are several species of Lycium, which are all known by the English name of Box-thorn; but L. barbarum is also called the Duke of Argyle’s Tea-tree, from a story told of this plant being sent to a Duke of Argyle early in the last century, instead of the true Tea-tree. The story, however, is very doubtful; and the more so, as in France, the dwarf Chinese Elm is called Thé de l’Abbé Gallois, as it is said, from a similar cause.
Cestrum Parqui is a very handsome half-hardy shrub, which may be placed in this division from its berry-like fruit. It has a funnel-shaped corolla, with a five-lobed limb, enclosing its five stamens. The flowers are disposed in an upright raceme; they are yellow, and very fragrant. The berries are of a very dark blue, and almost black when ripe. Vestia is another genus very nearly allied to Cestrum, but the stamens project beyond the mouth of the corolla instead of being enclosed within it; and the flowers, which are produced singly, have a very disagreeable smell.
TRIBE II.—NICOTIANEÆ.
The plants included in this tribe agree with those of the preceding division, in having the corolla generally folded in large plaits in the bud; but they are distinguished by having all capsular fruit: that is, in all the plants belonging to this tribe, the seed-vessel is dry and hard when ripe, and not soft and pulpy like a berry. The species have nearly all funnel-shaped flowers, with a long tube and a spreading limb; the tube is generally very long in proportion to the limb, and it is often inflated, so as to appear much wider in the upper part than near the calyx.
The Virginian Tobacco (Nicotiana tabacum) is an example of an inflated tube to the corolla (see fig. 70, a); the limb
Fig. 70.—Virginian Tobacco. is small and divided into five pointed segments; and the capsule (b), which opens at the point into four valves when ripe, contains numerous seeds. The whole plant is covered with a clammy down, particularly the leaves, which are large and flabby, and which have their footstalks dilated at the base, so as partly to enfold the stem. There are many species of Nicotiana, some of which are very ornamental. It is the dried leaves that are used as tobacco, or ground into snuff.
The Petunias are so well known, that I need say very little of the general form of their flowers, except to point out the connexion between them and the Tobacco. The corolla is salver-shaped, with a cylindrical tube, wider at the top than at the base, and a five-lobed limb. There are five stamens of unequal length, which are hidden in the tube of the corolla. The stigma has a broad head which is slightly two-lobed; and the calyx remains on the ripe capsule, which is two-celled, and opens in the upper part with two valves. The seeds are numerous and very small, and the leaves are pubescent and slightly clammy. If my readers will take the trouble to compare the Petunia and the Tobacco, they will be surprised to find how much the flowers are botanically alike. The differences are, that the calyx is more leaf-like in the Petunia than in the Tobacco; and the corolla of the Petunia is somewhat oblique, that is, two of the segments are smaller than the others; the filaments, also, are thickened at the base. It will appear extraordinary to every one acquainted with the flowers of the purple and the white Petunias, to find that some botanists have placed them in different genera. Such, however, is the case. On cutting open the delicate little seed of the white Petunia (P. nyctaginiflora), which it must have been very difficult to do, and ex amining it in a very powerful microscope, the embryo or germ of the future plant was found to be curved like that of most of the other Solanaceæ; whereas when the seed of the purple Petunia (P. phœnicea or violacea) was examined in the same manner, the embryo was discovered to be straight. This purple Petunia has consequently puzzled botanists as much as some of the other plants I have had occasion to mention; and it has been called successively Petunia violacea, Salpiglossis integrifolia, Nierembergia phœnicea, and Petunia phœnicea.