Fig. 493.—Deutzia crenata. Longitudinal section of flower.
Order 4. Hydrangeaceæ. Shrubs, with simple, opposite leaves, without stipules; flowers generally epigynous, 4–5-merous (Fig. [493]).—Hydrangea (H. hortensia, etc.). Shrubs from N. Am. and E. Asia; corolla often valvate. The inflorescence, as in the case of the inflorescence of Viburnum opulus (Guelder Rose), has often irregular, large, but barren flowers at the circumference, whilst the others are much smaller, regular and ☿; the barren flowers are mostly 4-merous; in these cases it is the calyx which is large and petaloid, while the other parts of the flower are more or less suppressed. The branches of the inflorescence appear to be partially devoid of floral-leaves, since they are displaced upon the main axis.—Philadelphus; racemes (with terminal flower), sepals 4 (valvate), petals 4 (twisted), stamens many, and carpels 4 (opposite the petals), forming a 4-locular ovary. The numerous stamens (20–30) occur by the splitting of the sepal-stamens and are often therefore placed in distinct bundles. Fruit a capsule. Ph. coronaria (Syringa, Mock Orange-blossom), from S. Eur., is a common ornamental shrub, as also is Deutzia (Fig. [493]) from N. Am. and E. Asia. The latter has S5, P5, A5 + 5, G3.—About 70 species.
Order 5 (?). Pittosporaceæ. This order has its home especially in Australia (90 species). The flower has S5, P5, A5 (episepalous), G2 (3–5), most frequently a unilocular ovary with many ovules in 2 rows, borne on 2 parietal placentæ, or a bilocular ovary. Some have berries, others capsules. Pittosporum, Citriobatus, Sollya, Billardiera.
Order 6. Hamamelidaceæ. Flowers more or less epigynous, with S4, P0 or 4, 4 fertile sepal-stamens, and 4 barren petal-stamens, bilocular ovary with 1–2 ovules in each loculus. Fruit a capsule. Hamamelis: one species in Japan and one in N. Am. Fothergilla. Liquidambar: monœcious; flowers in capitula or spikes; ♂-flowers without perianth, stamens indefinite; ♀-flower: slight perianth, 2-locular ovary with many ovules. Officinal: “Styrax-balsam,” which is obtained by boiling the bark of Liq. orientalis, from Asia Minor. Liquidambar and Parrotia are found as fossils in the Upper Oligocene; Hamamelis perhaps in the Chalk.
Finally two orders with very reduced flowers are included in this family.
Order 7. Platanaceæ. Trees, with large, scattered, palminerved and lobed leaves, and ochreate stipules; the buds are concealed in a hollow at the base of the petiole. The bark falls off in large scales. ♂-and ♀-flowers (monœcious) in crowded, spherical inflorescences which are placed at wide intervals on a terminal, thin, and pendulous axis. The flowers have an insignificant calyx and corolla; the ♂-flower has few stamens; ♀-flower, perigynous, with 4 free carpels, 1 pendulous, orthotropous ovule in each. Fruit a nut; endosperm absent. 5 species; frequently grown in avenues and parks. P. occidentalis (N. Am.); P. orientalis (W. Asia.).
Order 8. Podostemaceæ. Aquatic plants, especially in swiftly running water, with somewhat of an Alga-like, Moss-like, or thalloid appearance; they show themselves in many ways to be adapted to their mode of life and situations (having a dorsiventral creeping stem, the flowers sunk in hollows, a formation of haptera upon the roots, and thalloid assimilating roots and thalloid stems, etc.). Tropical; 100 species.
Family 20. Rosifloræ.
The leaves are scattered, stipulate, or have at least a well developed sheath, which is generally prolonged on each side into a free portion (“adnate stipules”). The flowers are regular, perigynous or epigynous. Calyx and corolla 5 (-4)-merous with the usual position. The corolla is always polypetalous. The stamens are present in very varying numbers (5–∞) and position, but always placed in 5-or 10-merous whorls; they are frequently 20 in 3 whorls (10 + 5 + 5; see Figs. [494], [502], [505]); the nearer they are placed to the circumference, the longer they are; they are generally incurved in the bud, or even rolled up. The number of the carpels is from 1–∞; in most cases all are individually free (syncarp), and when they are united it is in every case with the ovaries only, whilst the styles remain more or less free (Pomaceæ, species of Spiræa). The seeds have a straight embryo, and usually no endosperm.