Usually lianas, sometimes shrubs or small trees, provided with characteristic unicellular hairs which are generally centrally attached (fig. 11). Leaves opposite, rarely subopposite or in whorls of 3, mostly petioled, simple and mostly entire, often provided with superficial glands beneath, especially at the base. Stipules mostly present, variable. Inflorescences simple or slightly paniculate at the base, bracteate, raceme-like; pedicels articulated, bracteolate. Flowers often conspicuous, bisexual, but often parts of the gynoecium or androecium abortive, or rarely polygamous, actinomorphic to zygomorphic. Sepals 5, free or slightly connate, persistent, calyx outside sometimes provided with 1-10 distinct glands. Petals 5, free, imbricate, m...