Habit and leaf form. Small shrubs (with rigid, opposite branches); resinous (from cells in the leaf epidermis). Xerophytic. Leaves small; opposite; flat, or folded (blackening and folding fanlike when dry, expanding and greening again after rain); more or less connate (the petiole bases of the opposite leaves sheathing); aromatic; simple. Lamina entire; oblong, or obovate (cuneate-flabellate or narrowly elliptic, toothed across the broadly rounded apex); palmately veined; without cross-venules. Leaves stipulate. Stipules intrapetiolar (subulate, on the sheathing petiole bases); free of one another; persistent (with the petioles). Lamina margins apically dentate. Vernation plicate.
Leaf anatomy. Stomata present; anomocytic.
The mesophyll containing calcium oxalate crystals. The mesophyll crystals druses.
Stem anatomy. Cortical bundles absent. Medullary bundles absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Xylem with tracheids; with vessels. Vessel end-walls oblique; scalariform, or reticulately perforated. Primary medullary rays narrow (uniseriate). Wood parenchyma apotracheal.
Reproductive type, pollination. Plants dioecious. Gynoecium of male flowers absent. Floral nectaries absent. Anemophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in spikes, or in catkins. Inflorescences erect spikes or catkins. Flowers bracteate; regular; cyclic. Hypogynous disk absent.
Androecium 4, or 38. Androecial members free of one another (and 4), or coherent (when 38, then connate by their filaments). Androecium of male flowers, exclusively of fertile stamens. Stamens 38 (with large anthers). Anthers basifixed; non-versatile; dehiscing via longitudinal slits (? not by valves); latrorse; more or less appendaged. The anther appendages apical (representing a small apical prolongation of the connective). Endothecium developing fibrous thickenings. Pollen shed in aggregates; in tetrads. Pollen grains aperturate; 3 aperturate; weakly colpate; 2-celled.
Gynoecium 34 carpelled. The pistil 34 celled. Gynoecium syncarpous; synovarious; superior. Ovary 34 locular. Gynoecium stylate. Styles 34; free; short, broad, recurved. Stigmas 34 (ventral, decurrent). Placentation axile. Ovules 1050 per locule (rather numerous); funicled; horizontal; biseriate; anatropous; bitegmic; crassinucellate. Endosperm formation nuclear.
Fruit non-fleshy; a schizocarp. Mericarps 34; comprising follicles (the carpels separating septicidally and opening ventrally). Seeds copiously endospermic. Endosperm oily. Seeds minute, or small. Embryo well differentiated. Cotyledons 2.
Physiology, biochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins present; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid present.
Geography, cytology. Paleotropical. Tropical. Southern tropical Africa, Madagascar. 2n = 20.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Rosiflorae; Hamamelidales. Cronquists Subclass Hamamelidae; Hamamelidales. APG (1998) Eudicot; core Eudicot; neither Rosid nor Asterid; unassigned at ordinal level. Species 2. Genera 1; only genus, Myrothamnus.
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).