Burseraceae Kunth

Scientific Description

Common name. Frankincense Family.

Habit and leaf form. Trees, or shrubs; bearing essential oils (in the bark); resinous. Leaves alternate; spiral, or distichous (rarely); petiolate; non-sheathing; gland-dotted (rarely), or not gland-dotted; aromatic (resinous, but usually not punctate); compound; pinnate, or ternate, or unifoliolate (rarely); without stipules (usually), or with stipules (rarely); without a persistent basal meristem. Domatia recorded (one genus); represented by pits, or hair tufts. Stem anatomy. Nodes multilacunar. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite, or functionally male, or functionally female, or hermaphrodite, functionally male, and functionally female. Unisexual flowers present, or absent. Plants hermaphrodite, or dioecious, or polygamomonoecious.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes, in racemes, and in heads. Inflorescences often in thyrses. Flowers small; regular; 3–5 merous; cyclic; tetracyclic, or pentacyclic. Hypogynous disk present, or absent. Perianth with distinct calyx and corolla (usually), or sepaline (corolla sometimes lacking); 6–10; normally 2 -whorled; isomerous. Calyx (3–)4, or 5; 1 -whorled; gamosepalous (the sepals usually basally connate); imbricate, or valvate; regular. Corolla when present, (3–)4, or 5; 1 -whorled; polypetalous, or gamopetalous (rarely); imbricate, or valvate; regular. Fertile stamens present, or absent (staminodes in female flowers). Androecium 3–5, or 6–10. Androecial members free of the perianth; markedly unequal (often, when two whorls), or all equal; free of one another (usually), or coherent (rarely); when coherent 1 - adelphous (via connate filaments); 1 -whorled, or 2 -whorled. Androecium exclusively of fertile stamens (usually), or including staminodes. Stamens 4–5, or 8–10; diplostemonous (usually), or isomerous with the perianth; when one whorled alternisepalous. Anthers dorsifixed (slightly), or basifixed; versatile (slightly), or non-versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged, or unappendaged. Fertile gynoecium present, or absent (in male flowers). Gynoecium (2–)3–5 carpelled. The pistil (2–)3–5 celled. Carpels reduced in number relative to the perianth to isomerous with the perianth. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; superior. Ovary plurilocular; (2–)3–5 locular. Styles 1. Placentation axile. Ovules (1–)2 per locule; pendulous; epitropous; with ventral raphe (micropyle superior); non-arillate; hemianatropous.

Fruit and seed features. Fruit fleshy, or non-fleshy; indehiscent (usually), or dehiscent; a drupe (usually), or a capsule (rarely). Seeds non-endospermic (or almost so). Cotyledons 2. Embryo chlorophyllous (2/2). Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C₃.

Geography, cytology, number of species. World distribution: widespread. X = 11, 13, 23. 500 species.