Including Hirtellaceae Horan. (p.p.), Legnotid(ace)ae Endl., Macarisiaceae J.G. Agardh corr. Bullock, Macharisi(ac)eae J.G. Agardh, Paletuvieraceae Lam. ex Kuntze
Excluding Anisophylleaceae
Habit and leaf form. Trees, or shrubs (often mangroves). Helophytic. Leaves opposite (but not decussate); leathery; petiolate; simple. Lamina entire; pinnately veined. Leaves stipulate. Stipules interpetiolar (sheathing the terminal bud); caducous. Lamina margins entire.
Leaf anatomy. Mucilaginous epidermis present, or absent. Stomata anomocytic.
The mesophyll with sclerencymatous idioblasts, or without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells (Rhizophora).
Stem anatomy. Cork cambium present; initially superficial. Nodes tri-lacunar. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. `Included' phloem absent. Xylem with tracheids; with vessels. Vessel end-walls scalariform, or simple, or scalariform and simple. Vessels without vestured pits. Wood parenchyma apotracheal, or paratracheal.
Reproductive type, pollination. Hermaphrodite, or polygamomonoecious (rarely); plants viviparous (in mangrove species), or not viviparous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in `inflorescences', or solitary (rarely, then axillary); when aggregated, in cymes, or in racemes. The terminal inflorescence unit cymose, or racemose. Inflorescences axillary. Flowers regular; usually 4 merous, or 5 merous. Free hypanthium present (the hypanthium sometimes prolonged beyond the ovary), or absent.
Perianth with distinct calyx and corolla; 6-32; 2 whorled; isomerous. Calyx (3-)4-5(-16); 1 whorled; polysepalous; regular; commonly fleshy (or leathery); persistent; valvate. Corolla (3-)4-5(-16); 1 whorled; polypetalous (the petals often shorter than the sepals); contorted (or infolded); commonly fleshy. Petals clawed, or sessile; deeply bifid, or bilobed, or fringed (lacerate), or entire.
Androecium 8-25 (or more). Androecial members free of the perianth (generally inserted on the outer edge of the perigynous or epigynous disk); free of one another, or coherent (sometimes with the filaments basally connate); generally 1 - whorled. Androecium exclusively of fertile stamens. Stamens 8-30; diplostemonous (often paired opposite the petals), or triplostemonous, or polystemonous; filantherous, or with sessile anthers. Anthers introrse; bilocular, or four locular to many locular (cross partitioned, in Rhizophora); tetrasporangiate. Pollen grains aperturate; 3(-4) - aperturate; colporate (to colporoidate, sometimes zonorate); 2-celled.
Gynoecium 2-5(-6). Carpels reduced in number relative to the perianth, or isomerous with the perianth. Gynoecium syncarpous; eu-syncarpous; superior to inferior. Ovary 1 locular (by failure to partition), or 2-5(-6) locular. Gynoecium when G2, median. Epigynous disk present, or absent. Gynoecium stylate. Styles 1; apical. Stigmas 1 (shallowly to clearly lobed). Placentation when unilocular, apical; usually axile to apical. Ovules 2 per locule (usually), or 3-6 per locule (seldom); pendulous; with ventral raphe; arillate, or non-arillate; hemianatropous, or anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3 (uninucleate); not proliferating. Synergids pear-shaped. Endosperm formation nuclear. Endosperm haustoria present; chalazal (at least in Ceriops).
Fruit fleshy (usually), or non-fleshy; when dry dehiscent, or indehiscent; a capsule (rarely), or a berry, or a drupe. Seeds copiously endospermic. Endosperm oily (and fleshy). Embryo well differentiated. Cotyledons 2. Embryo straight. Micropyle zigzag.
Seedling. Germination phanerocotylar, or cryptocotylar.
Physiology, biochemistry. Not cyanogenic. Alkaloids present, or absent. Iridoids absent. Proanthocyanidins present; cyanidin, or delphinidin. Flavonols present; quercetin, or kaempferol and quercetin. Ellagic acid present (Cassipourea), or absent (Rhizophora). Saponins/sapogenins absent. Anatomy non-C4 type (Bruguiera, Ceriops, Pellacalyx, Rhizophora).
Geography, cytology. Sub-tropical to tropical. Pantropical and subtropical, concentrated in the Old World. X = 8, 9.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren's Superorder Myrtiflorae; Rhizophorales. Cronquist's Subclass Rosidae; Rhizophorales. Takhtajan's Subclass Rosidae; Myrtanae; Myrtales. Species 120. Genera 15; Anopyxis, Blepharistemma, Bruguiera, Carallia, Cassipourea, Ceriops, Comiphyton, Crossostylis, Dactylopetalum, Gynotroches, Kandelia, Macarisia, Pellacalyx, Rhizophora, Sterigmapetalum, Weihea (= Cassipourea).
Economic uses, etc. Some yield wood used for underwater construction and piling, and tannins are obtained from the bark.
Illustrations. rhizo387.gif rhizo604.gif
Additional, to be intercalated. Stipules with colleters (secreting mucilage) (sometimes, inside at the base), or without colleters.
