| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Marcgraviaceae Choisy

Habit and leaf form. Shrubs and lianas (mostly), or shrubs, or trees (small, seldom). Self supporting, or epiphytic, or climbing; when climbing, root climbers. Often conspicuously heterophyllous (the leaves dimorphic, those on juvenile rooting vegetative shoots sessile and distichous, those on nonrooting shoots petiolate and spiral). Leaves alternate; spiral and distichous; leathery; petiolate, or petiolate and sessile; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Domatia occurring in the family (recorded in 2 genera); manifested as pits.

Leaf anatomy. The leaf lamina dorsiventral. Extra-floral nectaries present (often), or absent. Stomata present; mainly confined to one surface (abaxial); staurocytic. Hairs absent. Adaxial hypodermis present (aqueous). Lamina with secretory cavities. Secretory cavities containing resin. The mesophyll with sclerenchymatous idioblasts; containing crystals. The crystals raphides. Minor leaf veins without phloem transfer cells (Norantea).

Axial (stem, wood) anatomy. Young stems with solid internodes. Pith homogeneous, or heterogeneous (consisting of thin-walled cells, often often with branched idioblasts interspersed). Cork cambium present; initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays mixed wide and narrow.

The wood diffuse porous. The vessels small to large; solitary, radially paired, and in radial multiples. The vessel end-walls simple, or scalariform and simple. The vessels without vestured pits; without spiral thickening. The axial xylem with tracheids; with fibre tracheids; with libriform fibres; including septate fibres, or without septate fibres. The parenchyma apotracheal, or paratracheal. The secondary phloem not stratified. ‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite (often with some sterile flowers). Pollination often ornithophilous (and pollinated by humming-birds, but sometimes self-pollinated or even cleistogamous).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, or in spikes, or in umbels. The ultimate inflorescence units racemose. Inflorescences terminal; racemes, spikes or umbels, often pendulous. Flowers bracteate (some of the bracts — usually those associated with sterile flowers — strongly modified into brightly coloured, pitcherlike, saccate, spurred or hooded nectariferous organs); calyptrate, or not calyptrate; regular; cyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 8–10; 2 whorled; isomerous. Calyx 4, or 5; 1 whorled; polysepalous, or gamosepalous (then basally connate); regular; imbricate. Corolla 4, or 5; 1 whorled; polypetalous, or gamopetalous (sometimes basally connate, often (Marcgravia) connate distally); calyptrate (Marcgravia), or not calyptrate (when not distally connate).

Androecium 3–40. Androecial members branched, or unbranched (?); free of the perianth, or adnate (sometimes adnate to the base of the petals); free of one another, or coherent. Androecium exclusively of fertile stamens. Stamens 3–40; isomerous with the perianth to polystemonous. Anthers dehiscing via longitudinal slits; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. Anther wall initially with more than one middle layer (3 or 4). Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate (or colporoidate); 2-celled.

Gynoecium 2–8 carpelled. Carpels reduced in number relative to the perianth to increased in number relative to the perianth. The pistil 1 celled (initially), or 2–8 celled (when mature). Gynoecium syncarpous; eu-syncarpous; superior. Ovary 1 locular (initially), or 2–8 locular (ultimately becoming plurilocular by intrusion and fusion of the placental partitions). Gynoecium very shortly stylate, or non-stylate. Styles if detectable, 1; apical. Stigmas 1 (this simple or merely lobed). Placentation finally axile. Ovules 30–50 per locule (‘many’); anatropous; bitegmic; tenuinucellate. Outer integument not contributing to the micropyle. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed, or not formed (then the three nuclei degenerating early); when formed, 3; not proliferating; ephemeral. Endosperm formation cellular (with a micropylar haustorium in Marcgravia). Endosperm haustoria present; micropylar.

Fruit thick, rather fleshy to non-fleshy; indehiscent, or dehiscent (then only partly so, near the base); a capsule to capsular-indehiscent. Capsules basally loculicidal. Fruit 50–100 seeded (‘many’). Seeds scantily endospermic, or non-endospermic. Embryo well differentiated. Cotyledons 2. Embryo slightly curved, or straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. Inulin recorded (several records, Gibbs 1974). Not cyanogenic. Iridoids not detected. Proanthocyanidins present. Ellagic acid absent.

Geography, cytology. Neotropical. Tropical. Tropical and Central America, West Indies.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Theiflorae; Theales. Cronquist’s Subclass Dilleniidae; Theales. APG III core angiosperms; core eudicot; Superorder Asteranae. APG IV Order Ericales.

Species 100. Genera 5; Marcgravia, Norantea, Souroubea, Ruyschia, Caracasia.

Illustrations. • Marcgravia coriacea, M. eichleriana and M. oligandra: Fl. Bras. 2, 1858–79. • Le Maout and Decaisne: Marcgravia umbellata. • Norantea guianensis subsp. japurensis: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Norantea anomala, N. goyazensis and N. jussiaei: Fl. Bras. 2, 1858–79. • Norantea brasiliensis, N. cacabifera, N. guianensis and N. oxystylis: Fl. Bras. 2, 1858–79. • Souroubea corallina, as Ruyschia: Martius, Nova Gen. et Spec. Pl. Brasiliensium 3 (1829). • Ruyschia amazonica: Lindley.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 8th June 2026. delta-intkey.com’.

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