Small, medium-sized or large, solitary or clustered, armed or unarmed, hapaxanthic or pleonanthic, hermaphroditic, polygamous, monoecious or dioecious plants. Stems woody, slender to massive, very short to very tall, creeping, subterranean, climbing or erect, usually unbranched aerially, rarely branching dichotomously, lacking cambium but sometimes increasing in diameter by diffuse growth, sometimes ventricose, internodes very short to elongate, leaf scars conspicuous or not, stilt roots present or absent, roots adventitious, sometimes modified into spines. Leaves alternate, spirally arranged, rarely distichous, later frequently splitting, unarmed or armed with spines or prickles, glabrous or variously scaly or hairy, sometimes with a ligule-like appendage on either side or in front of the petiole, sheaths sometimes forming a crownshaft; petiole usually present, terete or variously channelled or ridged, unarmed or bearing spines or teeth, glabrous or variously scaly or hairy; hastulae present or absent; blade palmate, costapalmate, pinnate, bipinnate or bifid, or entire and pinnately veined, plicate in bud, splitting along the adaxial folds (induplicate) or abaxial folds (reduplicate), rarely splitting between the folds, or not splitting; segments or leaflets lanceolate or linear to rhomboid, or wedge-shaped, \/-shaped in cross-section (induplicate) or /\- shaped (reduplicate), single-fold or manyfold, a midrib and numerous parallel secondary veins usually present, segments very rarely splitting further between the secondary veins, tips acute, acuminate, truncate, oblique or bifid, praemorse or irregularly toothed or lobed, sometimes armed with spines or bristles along the margins and/or main veins, variously scaly and hairy, transverse veinlets conspicuous or obscure; proximal leaflets sometimes modified as spines (acanthophylls), rachis prolonged distally into a climbing whip (cirrus) in many climbing palms, sometimes also bearing acanthophylls. Inflorescence axillary, solitary or multiple, infrafoliar, interfoliar or aggregated into a suprafoliar compound inflorescence, spicate or branched to up to 6 orders, usually maturing acropetally, rarely basipetally, in some species of Calamus inflorescence modified as a climbing whip (flagellum); peduncle short to long; prophyll usually 2- keeled, very varied in shape and size, rarely subtending a firstorder branch; peduncular bracts 0–many, very varied in shape and size; rachis shorter or longer than the peduncle; rachis bracts similar to peduncular bracts, or dissimilar, or much reduced; rachillae (flower-bearing branches) short to long, slender to massive, rachilla bracts conspicuous or minute or apparently lacking, sometimes connate laterally and adnate to the rachilla to form pits containing the flowers. Flowers hermaphroditic or unisexual, then similar or dimorphic, sessile or stalked, borne singly or in cincinni of various forms including dyads, triads or acervuli, or rarely in short monopodial clusters; perianth rarely of similar parts, usually differentiated into sepals and petals, rarely uniseriate with a variable number of lobes; sepals (2) 3 (rarely more), distinct or variously connate, usually imbricate or basally connate, rarely valvate or widely separated; petals (2) 3 (rarely more), distinct or variously connate, valvate, imbricate or imbricate with briefly valvate tips; stamens (1–3) 6 (or many, up to 950 or more), filaments erect or inflexed in bud, free, or variously connate, or adnate to the petals, or both connate and adnate, anthers basifixed or dorsifixed, rarely didymous, or with widely separated anther sacs, straight or rarely twisted, introrse, latrorse, extrorse, or very rarely opening by pores; pollen circular or elliptic in polar view, inaperturate, monoporate, diporate, triporate, monosulcate, disulcate, trior tetrachotomosulcate, exine intectate or tectate, very varied in ornamentation; staminodes ranging from tooth-like to well developed, distinct or connate, sometimes adnate to the petals or gynoecium, rarely absent; gynoecium apocarpous with (1–2) 3 (4) carpels, or variously syncarpous with 3 or rarely more (to 10) locules, or pseudomonomerous with 1 fertile locule, carpels follicular or rarely ascidiform, glabrous, variously hairy, or covered with imbricate scales, or spiny, styles distinct or connate or not clearly differentiated, stigmas erect or recurved, rarely indistinct; ovule solitary in each locule, anatropous, hemianatropous, campylotropous or orthotropous, basally, laterally or apically attached, crassinucellate, integuments 2, the outer wide, the inner narrow, the outer or the inner or both integuments forming the micropyle; pistillode present or absent in the staminate flower, ranging from minute and often trifid to large, bottleshaped, exceeding the stamens. Fruit usually 1-seeded, sometimes 2–3–10-seeded, ranging from small to very large, stigmatic remains apical, lateral or basal; epicarp smooth or hairy, prickly, corky-warted, or covered with imbricate scales, mesocarp fleshy, fibrous or dry, endocarp not differentiated, or thin, sometimes with an operculum over the embryo, or thick and then often with 1–3 or more pores at, below or above the middle. Seed adhering to the pericarp or free, with thin or sometimes fleshy testa (sarcotesta), endosperm homogeneous or ruminate, sometime penetrated by the testa; embryo apical, lateral or basal. Germination adjacent-ligular, remote-ligular or remote-tubular; eophyll simple and entire, bifid, palmate or pinnate.