Arecaceae Bercht. & J.Presl

Scientific Description

Common name. Palm Family.

Habit and leaf form. Trees, or ‘arborescent’, or shrubs, or lianas (rarely diminutive undershrubs); evergreen. Self supporting, or climbing; often scrambling (by means of hooks on prolonged rachides, leaflets modified as spines, armed sterile inflorescence axes, etc.). Pachycaul. Mesophytic, or xerophytic. Leaves small to very large; alternate; spiral; leathery; petiolate; sheathing. Leaf sheaths tubular; with joined margins (but often splitting at maturity). Leaves nearly always compound; epulvinate; (falsely) pinnate, or palmate, or bipinnate (rarely). Leaf blades without cross-venules. Leaves ligulate (often, in palmate and costa-palmate forms), or eligulate; without a persistent basal meristem (presumably). Vernation conduplicate. Leaves becoming compound by ontogenetically predetermined splitting. Vegetative anatomy. Plants with silica bodies (hatshaped, spheroidal or ellipsoidal, occurring universally). Leaf anatomy. Leaf blade epidermis without differentiation into ‘long’ and ‘short’ cells. Stem anatomy. Secondary thickening absent (or slight, and then not cambial but from divisions in the ground parenchyma).

Reproductive type, pollination. Fertile flowers hermaphrodite, or functionally male and functionally female, or functionally male, or functionally female, or hermaphrodite, functionally male, and functionally female. Unisexual flowers present, or absent. Plants hermaphrodite (rarely), or monoecious, or dioecious, or polygamomonoecious. Floral nectaries present, or absent. Nectar secretion when produced, from the gynoecium (via septal nectaries), or from the androecium (via nectaries associated with the stamen bases). Anemophilous, or entomophilous (more often).

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in panicles (usually, and usually complex). The terminal inflorescence unit cymose. Inflorescences axillary (usually), or terminal; usually complex panicles; usually spatheate. Flowers small; more or less regular; 3 merous; cyclic (usually), or partially acyclic. Rarely the perianth acyclic, or the androecium acyclic. Perigone tube present, or absent. Perianth with distinct calyx and corolla, or of ‘tepals’, or vestigial to absent (rarely); 6 (usually), or 4, or 4–9 (rarely, when spiral); 2 -whorled (usually 3+3, occasionally 2+2), or 1 -whorled (rarely); isomerous (but the two whorls usually more or less dissimilar); sepaloid, or petaloid, or sepaloid and petaloid; when biseriate, usually different in the two whorls; usually white, or cream. Fertile stamens present, or absent (female flowers). Androecium 3, or 6, or 9, or 10–900 (i.e. occasionally very numerous). Androecial members free of the perianth, or adnate (to the perianth); free of one another, or coherent; 1 - adelphous (filaments often united into a tube or cup); 2 -whorled, or 3 -whorled (or acyclic). Androecium exclusively of fertile stamens, or including staminodes (? — assuming that references to staminodes refer to male-fertile flowers). Stamens 3, or 6, or 9, or 10–900 (or more); isomerous with the perianth, or diplostemonous (usually), or triplostemonous to polystemonous. Anthers dehiscing via longitudinal slits; latrorse; tetrasporangiate. Fertile gynoecium present, or absent (male flowers). Gynoecium 3(–10) carpelled. The pistil 1 celled, or 3–10 celled (usually). Carpels isomerous with the perianth, or increased in number relative to the perianth. Gynoecium apocarpous, or syncarpous (occasionally pseudomonomerous); eu-apocarpous, or synovarious to synstylovarious. Ovary unilocular, or plurilocular; when syncarpous 1 locular (rarely, by abortion of the other locules), or 3(–10) locular. Gynoecium non-stylate, or stylate. Styles 1, or 3(–10); when not completely joined, free to partially joined. Stigmas dry type; papillate; Group II type. Placentation sub apical, or basal (or ‘lateral’). Ovules 1 per locule; non-arillate; orthotropous, or anatropous, or campylotropous, or hemianatropous.

Fruit and seed features. Fruit fleshy, or non-fleshy; an aggregate (occasionally), or not an aggregate. The fruiting carpel when apocarpous (i.e. rarely), indehiscent; drupaceous. Fruit indehiscent (usually), or dehiscent (rarely); nearly always a berry, or a drupe (sometimes with a fibrous mesocarp); 1 seeded. Seeds endospermic. Endosperm ruminate, or not ruminate; oily (usually), or not oily. Seeds usually without starch. Cotyledons 1. Embryo achlorophyllous (9/9). Seedling. Germination consistently cryptocotylar (regardless of cotyledon form). Hypocotyl internode absent. Seedling collar not conspicuous. Cotyledon hyperphyll elongated, or compact; non-assimilatory. Coleoptile present, or absent. Seedling cataphylls absent. First leaf dorsiventral. Primary root persistent, or ephemeral.

Physiology, biochemistry. Photosynthetic pathway: C₃.

Geography, cytology, number of species. World distribution: pantropical and subtropical. X = 13–18; ploidy levels recorded only in Areca. 2500 species.

Economic uses, etc. Pantropically of great economic importance: coconut products, oils, dates, ivory nuts, carnauba wax, rattan cane, raffia, etc.