Fig. 591.—Lonicera.
Lonicera (Honeysuckle). Shrubs, sometimes twiners. The corolla in some species is considerably bilabiate (Fig. [591]), with 4 lobes in the upper lip, and 1 in the under lip, but in others more regular, tubular, or campanulate. The flowers are either borne in capitate inflorescences, which are compound and formed of closely compressed 3-flowered dichasia (sect. Caprifolium), or in dichasia with 2 flowers (the terminal flower is wanting). The ovaries and fruits coalesce in some (sect. Xylosteum). The opposite leaves in some species unite with each other and form a broad collar encircling the stem (Fig. [591]). Above the primary bud 1–2 accessory buds are often found in the leaf-axils.—Diervilla (Weigelia); with a 2-locular, 2-valved capsule.—Symphoricarpus (Snowberry) has an almost regular, funnel-shaped corolla; a peculiar feature is found in the ovary which has 4 loculi, the 2 median having many ovules in 2 rows, all of which are aborted; the 2 lateral ones, on the other hand, each have only 1 ovule which is developed. Different forms of leaves are frequently found on the same branch; they are entire or lobed.
2. Sambuceæ, Elder Group (Fig. [592]). This has a rotate, regular corolla, extrorse anthers, a very short and thick (or almost absent) style, with tripartite stigmas, and only 1 pendulous ovule in each of the 3 (-5) loculi of the ovary. The fruit is a “drupe” with 1–3 (-5) stones. The inflorescence is made up of cymes grouped in an umbel-like arrangement.
Sambucus (Elder, Fig. [592]) has imparipinnate leaves and a “drupe” with 3 (-5) stones. Between the calyx and the style a disc remains on the apex of the fruit. S. nigra with black fruit; S. racemosa with red fruit; S. ebulus is a perennial herb; the others are woody.—Viburnum (Guelder-rose) has simple leaves (penninerved or palminerved, entire, dentate or lobed), and a “drupe” with only 1 stone, which is compressed, cartilaginous, and parchment-like; 2 of the loculi of the ovary are aborted. (In V. opulus the marginal flowers of the inflorescence are barren, and in that case their corollas are generally specially large; the cultivated Viburnum has only barren flowers, with large corollas.)
Fig. 592.—Sambucus nigra: cor corolla; s calyx.
3. Linnæeæ. Linnæa borealis (the only species) is an extreme form of the order; it has a 2-flowered dichasium, funnel-shaped, slightly bilabiate corollas (2/3); 4 didynamous stamens. Two of the 3 loculi of the ovary have several ovules which are not developed, while the third has only 1 ovule, which developes into a seed. The fruit is a nut, which is enveloped by the two large bracteoles, which are covered by sticky, glandular hairs, and serve as a means of distribution. It is a small undershrub.
[Adoxa, which was formerly classed in this order, appears, according to recent investigations, to be more properly placed among the Saxifraginæ.]
In cases where the flowers are small, as in Sambucus and Viburnum opulus, they are rendered conspicuous by being arranged in closely-packed inflorescences; they are massed together and form large surfaces, and in the last named are still more conspicuous on account of the barren, but large ray-flowers, which are of service in this respect. Honey is secreted in the nectaries at the base of the styles. In the genera with rotate flowers, as Viburnum and other Sambuceæ, the honey lies so exposed and in such a thin layer, that only flies and insects with short probosces can procure it; bees, however, visit these flowers for the sake of the pollen. There is hardly any nectar in the Elder; self-pollination frequently takes place. The flowers of the Caprifoliaceæ, which, with their long corolla-tube are adapted for evening-and night-flying insects with long probosces, open in the evening, and at that time give off their strongest scent.
Distribution. 230 species; especially outside the Tropics in the Northern Hemisphere. In this country they are found especially in hedges and as under-shrubs.—Officinal: the flowers and fresh fruits of the Elder (S. nigra), the fruits (“berries”) being also used in the household. Ornamental shrubs: species of Lonicera, Symphoricarpus, Diervilla, which are chiefly from N. Am., Abelia and Viburnum.