Common name. Quassia Family.
Habit and leaf form. Trees and shrubs (producing characteristic triterpenoid lactones (simaroubalides), often with very bitter bark, wood and seeds). Mesophytic. Leaves alternate; spiral; petiolate; non-sheathing; not gland-dotted; simple (rarely), or compound (usually); pinnate (usually), or unifoliolate, or ternate. Leaf blades pinnately veined; cross-venulate. Leaves with stipules (rarely), or without stipules. Stipules when present, intrapetiolar. Leaf blade margins entire. Leaves without a persistent basal meristem. Domatia recorded (Ailanthus); represented by hair tufts. Stem anatomy. Nodes tri-lacunar, or multilacunar (7). 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 polygamomonoecious, or dioecious. Male flowers with pistillodes, or without pistillodes.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’ (often numerous); in cymes, or in racemes, or in spikes, or in panicles. The terminal inflorescence unit cymose, or racemose. Inflorescences axillary; compound panicles, spikes, racemes or thyrses. Flowers small; regular; 3–7 merous; cyclic; when hermaphrodite, pentacyclic. Floral receptacle developing an androphore, or developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present (usually), or absent; when present, extrastaminal. Perianth with distinct calyx and corolla (usually), or sepaline (corolla rarely absent); (6–)10(–14); 2 -whorled, or 1 -whorled (rarely); isomerous. Calyx (3–)5(–7); 1 -whorled; gamosepalous (usually basally connate), or polysepalous; imbricate (usually), or valvate; regular. Corolla (3–)5(–7); 1 -whorled; polypetalous; imbricate (usually), or contorted, or valvate; regular. Fertile stamens present, or absent (female flowers). Androecium (4–)10(–16). Androecial members free of the perianth; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens (4–)10(–16); diplostemonous (usually), or isomerous with the perianth (sometimes), or triplostemonous to polystemonous (Mannia); oppositisepalous (usually), or alternisepalous (rarely, e.g. Picrolemma). Filaments appendiculate (often with scales at the base), or not appendiculate. Anthers dorsifixed (usually), or basifixed (more or less, in Guilfoylia, Soulamea, and more or less ventrifixed in Ailanthus); versatile; dehiscing via longitudinal slits; introrse (usually), or extrorse to latrorse (Ailanthus, Soulamea); tetrasporangiate. Fertile gynoecium present, or absent (male flowers). Gynoecium 1 carpelled (Guilfoylia), or 2–5 carpelled. The pistil if monomeric or syncarpous, 2–5 celled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. Gynoecium monomerous, or apocarpous to syncarpous; of one carpel, or eu-apocarpous to semicarpous, or synstylous (i.e. carpels often free below, united only by the style or stigma), or synovarious to eu-syncarpous; superior. Carpel (when monomerous or apocarpous) apically stigmatic, or with a lateral style, or with a gynobasic style; (when free) 1 ovuled. Ovary plurilocular; if more or less syncarpous, 2–5 locular. Gynoecium stylate. Styles free, or partially joined; lateral, or ‘gynobasic’. Stigmas dry type; non-papillate; Group II type. Placentation axile. Ovules 1 per locule; pendulous; epitropous; with ventral raphe (the micropyle superior); hemianatropous to anatropous.
Fruit and seed features. Fruit fleshy, or non-fleshy; an aggregate, or not an aggregate. The fruiting carpel indehiscent; drupaceous, or baccate, or samaroid. Fruit when syncarpous indehiscent, or a schizocarp. Mericarps when schizocarpic samaroid, or comprising berrylets, or comprising drupelets. Fruit when syncarpous capsular-indehiscent, or a berry, or a drupe, or a samara. Seeds more or less non-endospermic. Cotyledons 2 (large, expanded). Embryo chlorophyllous (3/3); straight, or curved. Seedling. Germination phanerocotylar, or cryptocotylar.
Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C3.
Geography, cytology, number of species. World distribution: pantropical and subtropical, to Japan and central Argentina. X = 8, 13(+). 120 species.