Rhizophoraceae Pers.

Scientific Description

Common name. Red Mangrove Family.

Habit and leaf form. Trees, or shrubs (often mangroves). Helophytic. Leaves opposite (but not decussate); leathery; petiolate; simple. Leaf blades entire; pinnately veined. Leaves with stipules. Stipules interpetiolar (sheathing the terminal bud, sometimes with colleters inside at the base); with colleters (secreting mucilage), or without colleters; caducous. Leaf blade margins entire. Stem anatomy. Nodes tri-lacunar. Secondary thickening developing from a conventional cambial ring. Roots. Aerial roots present, or absent.

Reproductive type, pollination. Fertile flowers hermaphrodite, or hermaphrodite, functionally male, and functionally female (rarely). Unisexual flowers present, or absent. Plants hermaphrodite, or polygamomonoecious (rarely). Plants viviparous (in mangrove species), or not viviparous.

Inflorescence and flower features. 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; valvate; regular; commonly fleshy (or leathery); persistent. Corolla (3–)4–5(–16); 1 -whorled; polypetalous (the petals often shorter than the sepals); contorted (or infolded); commonly fleshy. Petals clawed, or sessile. Corolla members deeply bifid, or bilobed, or fringed (lacerate), or entire. Fertile stamens present, or absent (rarely — when flowers female, and then there are epipetalous staminodes). 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. Fertile gynoecium present, or absent (rarely, when flowers male). Gynoecium 2–5(–6) carpelled. The pistil 1 celled, or 2–5(–6) celled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. Gynoecium syncarpous; eu-syncarpous; superior to inferior. Ovary unilocular, or plurilocular; 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; epitropous; with ventral raphe; arillate, or non-arillate; hemianatropous, or anatropous.

Fruit and seed features. 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.

Special features. Mangroves, or non-mangrove species.

Geography, cytology, number of species. World distribution: pantropical and subtropical, concentrated in the Old World. X = 8, 9. 120 species.

Economic uses, etc. Some yield wood used for underwater construction and piling, and tannins are obtained from the bark.