Habit and leaf form. Trees and shrubs. Plants with neither basal nor terminal concentrations of leaves, or with terminal rosettes of leaves; rhizomatous. Self supporting (usually), or epiphytic. Stem growth conspicuously sympodial (appearing dichtomous). Pachycaul. Helophytic, or mesophytic (often maritime). Leaves medium-sized to very large; alternate (crowded at tops of branches); spiral (appearing so, through torsion of the stem), or tristichous (in fact); leathery; imbricate; sessile; sheathing. Leaf sheaths with free margins. Leaves simple. Leaf blades entire; folded (M-shaped in cross-section); narrowly ovate to triangular, or linear; parallel-veined; without cross-venules. Leaves eligulate. Vernation plicate. Vegetative anatomy. Plants without silica bodies. Leaf anatomy. Hairs absent. Stem anatomy. Secondary thickening absent (with compound vascular bundles).
Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Unisexual flowers present. Plants dioecious. Female flowers aggregated in ‘inflorescences’ (forming cylindric heads (cephalia) of densely packed ovaries); with staminodes, or without staminodes. Male flowers without pistillodes, or with pistillodes (then produced above the stamens at the top of the phalanges, e.g. in subgenus Martellidendron). Anemophilous and entomophilous.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in spikes, or in heads. Inflorescences terminal; spatheate. Flowers minute, or small. Floral receptacle developing an androphore (in some cases the sessile anthers crowded on the discoid, enlarged apex of a staminal column), or with neither androphore nor gynophore. Perianth absent. Fertile stamens present, or absent (female flowers). Androecium of male-fertile flowers 10–100 (?—‘many’, the situation complicated by the fact that homologies are so unclear that it is not possible with any certainty to distinguish ‘flowers’ from aggregates of flowers). Androecial members branched (frequently), or unbranched; variously coherent (in clusters of few (triads) or many, racemosely to umbellately arranged in phalanges, often with stemonophores), or free of one another (and then no trace of flower structure discernable). Stamens 10–100 (‘many’ — regardless of what constitutes a single flower); filantherous, or with sessile anthers. Anthers basifixed; dehiscing via longitudinal slits; appendaged (via apical prolongation of the connective), or unappendaged. Fertile gynoecium present, or absent (male flowers). Gynoecium 1–30 carpelled. The pistil 1–30 celled. Gynoecium monomerous, or apocarpous to syncarpous (forming phalanges); of one carpel, or eu-apocarpous to synovarious; superior. Carpel incompletely closed (frequently, in the stigmatic region), or fully closed; stylate, or non-stylate (then stigmas sessile); apically stigmatic; (when apocarpous or one-carpelled) 1 ovuled. Placentation marginal, or basal. Ovary (when syncarpous) unilocular, or plurilocular; 2–30 locular (i.e. to ‘many’). Placentation when bi- multilocular basal. Ovules when plurilocular 1 per locule; anatropous.
Fruit and seed features. Fruit fleshy to non-fleshy; more or less an aggregate, or not an aggregate. The fruiting carpels (when apocarpous) coalescing into a secondary syncarp, or not coalescing. The fruiting carpel indehiscent; drupaceous. Gynoecia of adjoining flowers generally combining to form a multiple fruit. The multiple fruits coalescing (to varying extents), or not coalescing. Fruit 1 seeded. Seeds endospermic. Endosperm oily. Seeds minute; with starch. Embryo well differentiated (small). Cotyledons 1. Embryo straight. Seedling. Hypocotyl internode present. Mesocotyl absent. Seedling collar not conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile absent. Seedling cataphylls absent. First leaf dorsiventral. Primary root ephemeral.
Economic uses, etc. Leaves are used for thatch, matting, clothing and containers, and the immature fleshy perianths of some species are edible.