The families of flowering plants
Habit and leaf form. Trees, shrubs, and lianas. Rhizomatous. Self supporting (usually with prop roots at the base of the stem), or epiphytic, or climbing; when climbing, root climbers. Stem growth conspicuously sympodial (appearing dichtomous). Pachycaul. Helophytic, or mesophytic (often maritime). Leaves medium-sized to very large; alternate; spiral (appearing so, through torsion of the stem), or tristichous (usually, in fact), or four-ranked (rarely); leathery; imbricate; sessile; sheathing. Leaf sheaths with free margins. Leaves simple. Lamina entire; usually linear, or lanceolate; parallel-veined; without cross-venules. Leaves eligulate. Vernation plicate.
General anatomy. Plants without silica bodies.
Leaf anatomy. Stomata present; tetracytic. The mesophyll containing mucilage cells (with raphides); containing crystals. The crystals raphides, or druses (?), or solitary-prismatic. Foliar vessels present; with scalariform end-walls. Minor leaf veins without phloem transfer cells (Pandanus).
Axial (stem, wood) anatomy. Secondary thickening absent (stems with compound vascular bundles).
The vessel end-walls scalariform.
Root anatomy. Root xylem with vessels; vessel end-walls scalariform.
Reproductive type, pollination. Unisexual flowers present. Plants dioecious, or polygamodioecious. Female flowers with staminodes (often), or without staminodes. Pollination anemophilous, or entomophilous, or ornithophilous, or cheiropterophilous (but mostly by wind).
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in panicles, in racemes, and in heads (often crowded into dense panicles). Inflorescences terminal; spatheate. Flowers minute, or small.
Perianth of tepals (?Sararanga), or absent (Freycinetia and Pandanus); 3–4 (Sararanga); when present, joined (cupuliform); 1 whorled; in Sararanga, more or less sepaloid (?).
Androecium of male-fertile flowers 10–100 (?many, the situation in Freycinetia and Pandanus 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 (ostensibly), or unbranched (?); free of the perianth; variously coherent (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. Tapetum amoeboid. Pollen grains aperturate; 1 aperturate; sulcate, or ulcerate; 2-celled.
Gynoecium (1–)80 carpelled. The pistil 1 celled (when monomerous), or 2–100 celled (to many, when syncarpous). Gynoecium monomerous (rarely), or apocarpous to syncarpous; of one carpel (rarely), or eu-apocarpous to eu-syncarpous (syncarpous in Sararanga and Freycinetia, carpels free or connate in Pandanus); superior. Carpel (when apocarpous or unilocular) 1–5 ovuled. Placentation when apocarpous or one-carpelled marginal, or basal. Ovary when syncarpous 1 locular (in Freycinetia), or 2–100 locular (i.e. to many). Placentation when bi- multilocular axile (Freycinitia), or basal. Ovules when plurilocular 1–5 per locule (carpels uniovulate in Pandanoideae, several-ovuled in Freycinetioideae); anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle (Freycinetia), or not contributing to the micropyle. Embryo-sac development Polygonum-type, or Allium-type. Antipodal cells formed; 3 (Freycinetia), or 64–200 (Pandanus, where the antipodals are supplemented by migration of nuclei from elsewhere); proliferating, or not proliferating. Hypostase present. Endosperm formation nuclear.
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 (1280 in Sararanga). Fruit when syncarpous, indehiscent; when syncarpous, a berry. Gynoecia of adjoining flowers generally combining to form a multiple fruit. The multiple fruits coalescing (to varying extents, in Pandanus), or not coalescing. Fruit 1 seeded. Seeds endospermic. Endosperm oily, or not oily. Seeds minute. Seeds with starch. Embryo well differentiated (small). Cotyledons 1. Embryo straight. Testa without phytomelan.
Seedling. Hypocotyl internode present (long). Seedling collar not conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile absent. Seedling cataphylls absent. First leaf dorsiventral. Primary root ephemeral.
Physiology, phytochemistry. Anatomy non-C4 type (Freycinetia, Pandanus). Acumulated starch exclusively pteridophyte type. Not cyanogenic. Alkaloids absent (3 species). Saponins/sapogenins absent. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent. Sieve-tube plastids P-type; type II.
Geography, cytology. Temperate (warm, a few), or temperate to sub-tropical. Southwest tropical Africa, Madagascar, India to Thailand, Malaysia and Australia. X = 30 (with aneuploidy).
Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Pandaniflorae; Pandanales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Pandanales.
Species 700. Genera 3; Freycinetia, Pandanus, Sararanga.
Economic uses, etc. Pandanus leaves are used for thatch, matting, clothing and containers, and the immature fleshy perianths of some species are edible.
Illustrations. • Technical details: Pandanus, Freycinetia. • Pandanus candelabrum (Thonner).
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 22nd July 2014. http://delta-intkey.com’.