The families of flowering plants
Alternatively Papayaceae Blume
Habit and leaf form. Small, soft-stemmed, palmlike trees, or arborescent, or shrubs, or herbs (prostrate, Jarilla only); laticiferous. Plants succulent (in the stem), or non-succulent. Pachycaul (commonly, with unbranched trunk and a terminal cluster of leaves), or leptocaul. Leaves large; alternate; petiolate; simple, or compound; commonly palmate (the leaflets sometimes pinnately lobed). Lamina when simple, entire (usually, more or less), or dissected (rarely); when simple, palmatifid (usually), or pinnatifid (rarely); palmately veined (usually), or pinnately veined (rarely, when simple and entire or pinnately lobed); cross-venulate. Leaves exstipulate (usually), or stipulate. Stipules when present, spiny.
General anatomy. Plants with laticifers (articulated, anastomosing). The laticifers in leaves and in stems.
Leaf anatomy. The leaf lamina dorsiventral. Stomata present; mainly confined to one surface (abaxial); anomocytic. Hairs present; eglandular, or eglandular and glandular (? - long, club-shaped glandular hairs with multicellular heads present along the veins and on the petiole). The mesophyll containing crystals. The crystals druses. Minor leaf veins without phloem transfer cells (Carica).
Axial (stem, wood) anatomy. Nodes tri-lacunar, or multilacunar. Primary vascular tissues comprising a ring of bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays wide.
The vessel end-walls simple. The vessels without vestured pits. The axial xylem without wood fibres. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones. Included phloem absent.
Reproductive type, pollination. Plants monoecious, or dioecious, or andromonoecious, or gynomonoecious, or polygamomonoecious (? usually dioecious or monoecious, but sometimes with some perfect flowers). Gynoecium of male flowers vestigial, or absent.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in inflorescences; when aggregated, in cymes. The ultimate inflorescence units cymose. Inflorescences axillary; loose, axillary, cymose. Flowers regular; 5 merous; cyclic. Free hypanthium absent.
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5 (small); 1 whorled; polysepalous, or gamosepalous; blunt-lobed, or toothed; regular; open. Corolla 5; 1 whorled; gamopetalous; contorted, or valvate; with a short tube in female flowers, a long one in male flowers; regular.
Androecium in male flowers, 5, or 10. Androecial members adnate (to the corolla tube); free of one another (Carica), or coherent (basally connate); when joined, 1 adelphous (forming a short tube); 1 whorled, or 2 whorled. Androecium (male flowers) exclusively of fertile stamens. Stamens 5, or 10; inserted in the throat of the corolla tube; isomerous with the perianth, or diplostemonous; oppositisepalous; alternating with the corolla members, or both alternating with and opposite the corolla members; filantherous, or with sessile anthers. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged (via a shortly prolonged connective), or unappendaged (?). Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with one middle layer. Tapetum glandular. Pollen grains aperturate; 3 aperturate; colporate; 2-celled.
Gynoecium 5 carpelled; partly petaloid (e.g. with petaloid stigmas), or non-petaloid. Carpels isomerous with the perianth. The pistil 1 celled, or 5 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 1 locular, or 5 locular. Gynoecium stylate. Styles 1, or 5; free to partially joined; apical. Stigmas 5; dry type; papillate; Group II type. Placentation when unilocular, parietal (the placentas more or less deeply intruded), or laminar-dispersed; when plurilocular, axile. Ovules in the single cavity 50–100 (or more many); 30–50 per locule (or more many); funicled (the funicle more or less enlarged); anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids apically broad, with filiform apparatus. Endosperm formation nuclear. Embryogeny by irregular early cleavages.
Fruit fleshy; indehiscent; a berry (large, melonlike). Seeds endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2 (broad, flat). Embryo achlorophyllous (1/1); straight.
Seedling. Germination phanerocotylar.
Physiology, phytochemistry. C3. C3 physiology recorded directly in Carica. Mustard-oils present (often). Not cyanogenic. Alkaloids present (carpaine), or absent. Iridoids not detected. Saponins/sapogenins present, or absent. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent (Carica).
Geography, cytology. Paleotropical and Neotropical. Sub-tropical and tropical. Tropical America (mainly) and West Africa (Cylicomorpha). X = 9.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Violiflorae; Violales. Cronquists Subclass Dilleniidae; Violales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Brassicales.
Species 55. Genera 4; Carica, Cylicomorpha, Jacaratia, Jarilla.
Economic uses, etc. Commercial edible fruit (papaw, pawpaw, papaya) from C. papaya.
Illustrations. • Carica papaya: Bot. Mag. 56 (1829). • Carica papaya (fruit): Bot. Mag. 56 (1829). • Technical details: Carica (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: 20th June 2017. delta-intkey.com/angio’.