Fig. 428.—Thea chinensis (reduced).
Closely allied to this order are: Order 15. Rhizoboleæ (with enormously large hypocotyl—hence the name), and Order 16. Marcgraviaceæ (partly epiphytes, with dimorphic leaves and cup- or helmet-like, coloured, honey-secreting floral-leaves, which serve to attract insects).
Order 17. Dipterocarpaceæ. This order has taken its name from the large wings attached to the fruits in Dipterocarpus (the wings being largely developed sepals); trees and shrubs from Trop. Asia. 180 species. Camphor ready prepared is found in the stem of Dryobalanops camphora. Hopea; Vateria.
Family 12. Gruinales.
The flowers are hypogynous, ☿, polypetalous, usually regular (except Pelargonium, Tropæolaceæ, Balsaminaceæ) and throughout 5-merous: S5, P5, A5 + 5, or 5 + 0, G5 (epipetalous). The stamens soon fall off and are obdiplostemonous, often united at the base (monadelphous); the corolla-stamens are in some completely suppressed (e.g. Balsaminaceæ, Fig. [438]), in others reduced to teeth (Linum, Fig. [431]; Erodium). The Tropæolaceæ have 3 carpels and only 8 stamens (Fig. [437]). Ring-like nectaries are not present, but at most only glandular bodies, borne outside the base of the stamens. Ovaries many-locular. The ovules as a rule are pendulous, with the micropyle directed outwards (Fig. [431], B), and the radicle therefore also points outwards. Usually herbs. Related to the Columniferæ.
Order 1. Oxalidaceæ. Most of the species are herbs with rhizomes; the leaves are stalked, compound, with entire leaflets which are folded and bent backwards in the bud (and in the sleep position), exstipulate; some species have sensitive leaves. The flowers (Fig. [429]) are regular, and have S5, P5, which are twisted to the left or right in æstivation, A5 + 5, all united at the base (monadelphous), gynœceum 5-carpellate, styles 5 free, stigmas capitate, ovary 5-locular, ovules numerous. The fruit is a capsule opening with clefts on the dorsal sutures through which the seeds are ejected, while the fleshy, external layer of the testa springs off elastically. Embryo straight. Endosperm.
Fig. 429.—Diagram of Oxal’s acetosella.
Oxalis (Wood-Sorrel). Leaves digitate. Species also occur with phyllodia, i.e. leaf-like petioles placed vertically without lamina; a few have pinnate leaves. The flowers are situated singly or in dichasia, and unipared scorpioid cymes. The pollination is effected by insects. Some species are trimorphic (long-, short-, medium-styled flowers) and some, e.g. O. acetosella, have cleistogamic flowers in addition to the ordinary ones. Glands are found on the outer side of the corolla-stamens or of all the stamens. O. tetraphylla and others have adventitious edible roots, resembling tap-roots.—Averrhoa is a tropical tree, with berries and pinnate leaves.