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The families of flowering plants

L. Watson and M.J. Dallwitz

Apocynaceae Juss.

Including Plumeriaceae Horan., Emetiaceae Dulac, Vincaceae von Vest, Willughbejieae (Willughbeiaceae) J.G. Agardh; excluding Asclepiadaceae, Periplocaceae, Plocospermataceae.

Habit and leaf form. Trees (a few, e.g. in Tabernaemontana, Dyera), or shrubs, or lianas (mostly), or herbs (e.g. Vinca); laticiferous. Climbing (usually), or self supporting (sometimes); mostly stem twiners (with hooks); twining anticlockwise (Dipladenia). Leaves persistent; alternate, or opposite, or whorled; when whorled 3 per whorl; ‘herbaceous’, or leathery; simple. Lamina entire; pinnately veined. Leaves stipulate (rarely), or exstipulate. Stipules when present, interpetiolar (small). Domatia occurring in the family (in 15 genera); manifested as pits, or pockets, or hair tufts.

General anatomy. Plants with laticifers (non-articulated, branched or unbranched). The laticifers in leaves and in stems.

Leaf anatomy. The leaf lamina dorsiventral (usually), or bifacial (e.g., isobilateral in Nerium oleander). Epidermis with crystal idioblasts (sometimes), or without crystal idioblasts. Stomata anomocytic, or paracytic (sometimes mixtures of anomocytics and paracytics), or cyclocytic (rarely). Hairs present (represented by diverse forms); eglandular, or glandular (often with glandular shaggy hairs at lamina bases and on the petiole). Complex hairs absent (the only recorded exception being Pachypodium). Adaxial hypodermis present (commonly), or absent. The mesophyll with sclerenchymatous idioblasts (‘spicular cells’ recorded in several genera, in the form of extensions from the sclerenchyma around the veins), or without sclerenchymatous idioblasts; containing crystals. The crystals raphides, druses, and solitary-prismatic. Midrib usually conspicuous (often with a bicollateral vascular bundle). Minor leaf veins without phloem transfer cells (Dipladenia, Trachelospermum, Vinca).

Axial (stem, wood) anatomy. Cork cambium present; initially deep-seated (rarely), or initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; bicollateral. Internal phloem present (usually, in the form of a ring or as bundles around the margin of the pith, sometimes with additional arcs of phloem more deeply seated in the pith). Secondary thickening developing from a conventional cambial ring, or anomalous. The anomalous secondary thickening via concentric cambia, or from a single cambial ring. Primary medullary rays usually narrow.

The wood semi-ring porous, or diffuse porous. The vessels usually small, or medium (sometimes), or large (rarely); solitary (commonly exclusively so), or radially paired, or in radial multiples, or clustered, or in tangential arcs. The vessel end-walls simple, or scalariform and simple (then with few bars). The vessels with vestured pits, or without vestured pits; with spiral thickening, or without spiral thickening. The axial xylem with tracheids; with vasicentric tracheids, or without vasicentric tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; at least sometimes including septate fibres, or without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal (usually), or paratracheal (in a few genera). ‘Included’ phloem present (Lyonsia), or absent. The wood not storied. Tyloses present, or absent.

Reproductive type, pollination. Plants hermaphrodite. Pollination mechanism conspicuously specialized (usually with a highly modified stylar head and specialised anthers).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The ultimate inflorescence units usually a panicle. Flowers bracteate; bracteolate; regular; usually 4–5 merous; cyclic; tetracyclic. Hypogynous disk usually present.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous; regular; imbricate (quincuncial); with the median member posterior. Corolla 5; 1 whorled; appendiculate (often, in the form of scales in the throat); gamopetalous. Corolla lobes markedly shorter than the tube to markedly longer than the tube. Corolla contorted (usually), or valvate (rarely, e.g. in some Urceola species); funnel-shaped, or hypocrateriform; regular; white, or yellow, or red, or pink, or purple, or blue.

Androecium 5. Androecial members adnate (epipetalous); united with the gynoecium (most Apocynoideae), or free of the gynoecium (most Plumerioideae); free of one another, or coherent; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; inserted near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube; isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers cohering, or connivent (often sagittate, empty below and prolonged into spines, sometimes united with the stylar head), or separate from one another; adnate; tetrasporangiate; appendaged (by prolongation of the connective), or unappendaged. Microsporogenesis successive, or simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with one middle layer, or initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; (2–)3–4 aperturate; porate, or colporate; 2-celled (8 genera), or 3-celled (7 genera).

Gynoecium 2 carpelled (nearly always), or 2–5(–8) carpelled (only in the 3 species of Pleiocarpa). The pistil 1–2 celled. Gynoecium syncarpous (but sometimes the carpels united only by their styles); synstylovarious to eu-syncarpous, or synstylous (Plumerieae, Pleiocarpa); superior, or partly inferior. Carpel when synstylous, 2–50 ovuled (to ‘many’?). Placentation when synstylous, marginal (ventral). Ovary when ovaries joined, 1 locular, or 2 locular, or 1–2 locular (or when synstylous with free ovaries, these usually 2 but 2–5(–8) in Pleiocarpa). Gynoecium when G2, i.e. nearly always, transverse. Styles 1. Stigmas 1 (the head usually massively thickened, contracted in the middle, with a ring, a ring of hairs or a membrane below); wet type, or dry type; papillate, or non-papillate; Group II type, Group III type, and Group IV type. Placentation when unilocular, with the two placentas parietal; when bilocular, axile, or apical (and sometimes the ovaries are bilocular with axile placentation below, and unilocular with parietal placentation above). Ovules in the single cavity when unilocular or incompletely bilocular 2–100 (?—to ‘many’); when bilocular, 2 per locule, or 4 per locule, or 6 per locule, or 25–50 per locule (‘many’); pendulous; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped. Endosperm formation nuclear. Embryogeny caryophyllad.

Fruit fleshy, or non-fleshy; dehiscent, or indehiscent, or a schizocarp. Mericarps when schizocarpic, 2; comprising follicles, or comprising berrylets, or comprising nutlets (?—‘indehiscent mericarps’), or comprising drupelets. Fruit when non-schizocarpic, a capsule, or a berry, or a drupe. Seeds copiously to scantily endospermic, or non-endospermic. Endosperm oily. Seeds usually flat; conspicuously hairy (comose, in the Apocynoideae), or not conspicuously hairy (Plumerioideae). Cotyledons 2; flat, or folded, or rolled. Embryo achlorophyllous (10/12); straight.

Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, phytochemistry. C3 and CAM. C3 physiology recorded directly in Apocynum, Nerium, Pachypodium, Plumeria, Rhazya. CAM recorded directly in Carissa (non-succulent), Pachypodium. Anatomy non-C4 type (Apocynum, Allamonda, Nerium, Plumeria). Sugars transported as sucrose, or as oligosaccharides + sucrose, or as sugar alcohols + oligosaccharides + sucrose. Cyanogenic (rarely), or not cyanogenic (mostly). Alkaloids present (mostly), or absent. Verbascosides not detected. Iridoids detected (in three genera); ‘Route II’ type (b), or ‘Route I’ type and ‘Route II’ type (doubtfully). Saponins/sapogenins present, or absent. Proanthocyanidins present, or absent; cyanidin (mostly), or cyanidin and delphinidin. Flavonols present, or absent; when present, kaempferol, or quercetin, or kaempferol and quercetin (mostly). Ellagic acid absent (14 species, 12 genera). Ursolic acid present. Aluminium accumulation demonstrated (a few genera only), or not found (mostly). Sieve-tube plastids S-type.

Geography, cytology. Temperate (a few), sub-tropical to tropical (mainly). Widespread. X = 8–12(+).

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae; Gentianales. Cronquist’s Subclass Asteridae; Gentianales. APG III core angiosperms; core eudicot; Superorder Asteranae; lamiid. APG IV Order Gentianales.

Species 1500. Genera 164; Acokanthera, Adenium, Aganonerion, Aganosma, Alafia, Allamanda, Allomarkgrafia, Allowoodsonia, Alstonia, Alyxia, Amocalyx, Ambelania, Amsonia, Ancylobotrys, Anechites, Angadenia, Anodendron, Apocynum, Arduina, Artia, Asketanthera, Aspidosperma, Baissea, Beaumontia, Bousigonia, Cabucala, Callichilia, Calocrater, Cameraria, Carissa, Carpodinus, Carruthersia, Carvalhoa, Cascabela, Catharanthus, Cerbera, Cerberiopsis, Chamaeclitandra, Chilocarpus, Chonemorpha, Cleghornia, Clitandra, Condylocarpon, Couma, Craspidospermum, Crioceras, Cycladenia, Cyclocotyla, Cylindropsis, Delphyodon, Dewevrella, Dictyophleba, Dipladenia, Diplorhynchus, Dyera, Ecdysanthera, Echites, Elytropus, Epigynium, Eucorymbia, Farquharia, Fernaldia, Forsteronia, Funtumia, Galactophora, Geissospermum, Gonioma, Grisseea, Hancornia, Haplophyton, Himatanthus, Holarrhena, Hunteria, Hymenolophus, Ichnocarpus, Isonema, Ixodonerium, Kamettia, Kibatalia, Kopsia, Lacmellea, Landolphia, Laubertia, Laxoplumeria, Lepinia, Lepiniopsis, Leuconotis, Lochnera, Lyonsia, Macoubea, Macropharynx, Macrosiphonia, Malouetia, Mandevilla, Mascarenhasia, Melodinus, Mesechites, Micrechtites, Microplumeria, Molongum, Mortoniella, Motandra, Mucoa, Neobracea, Neocouma, Nerium, Nouettea, Ochrosia, Odontadenia, Oncinotis, Orthopichonia, Pachypodium, Pachouria, Papuechites, Parahancornia, Parameria, Parepigynum, Parsonsia, Peltastes, Pentalinon, Petchia, Picralima, Plectaneia, Pleiocarpa, Pleioceras, Plumeria, Pottsia, Prestonia, Pycnobotrya, Quiotania, Rauwolfia, Rhabdadenia, Rhazya, Rhigospira, Rhodocalyx, Rhyncodia, Saba, Salpinctes, Schizozygia, Secondatia, Sindechites, Skytanthus, Spirolobium, Spongiosperma, Stemmadenia, Stephanostegia, Stephanostema, Stipecoma, Strempeliopsis, Strophanthus, Tabernaemontana, Tabernanthe, Temnadenia, Thenardia, Thevetia, Tintinnabularia, Trachelospermum, Urceola, Urnularia, Vahadenia, Vallariopsis, Vallaris, Vallesia, Vinca, Voacanga, Willughbeia, Woytkowskia, Wrightia, Xylinabaria, Xylinabariopsis.

General remarks. These compiled descriptions offer abundant evidence in terms of ‘esoteric characters’ (anatomical, embryological, biochemical), as well as conspicuous general morphlogical features, to justify retaining Asclepiadaceae, Periplocaceae and Plocospermataceae as separate families on practical grounds.

Economic uses, etc. Many past, inferior commercial sources of rubber (e.g. Carpodinus, Landolphia, Mascarenhasia), numerous showy ornamentals, several sources of drugs and alkaloids, edible fruit (‘Natal plum’) from Carissa carandas.


. . . . The sky-blue Periwinkle . . .
Pentagonally form’d, to mock the skill
Of proud geometers
(Hurdis, quoted by Ann Pratt, ‘Wild Flowers’ (1857) - Vinca minor)

Illustrations. • Le Maout and Decaisne: Vinca, Nerium. • Clitandra arnoldiana: Thonner. • Aganosma cymosa, as Echites: R. Wight, Ic. Pl. Indiae Orientalis 2 (1843). • Alyxia buxifolia: Rye, Flora of Perth Region 1 (1987). • Apocynum androsaemifolium: Bot. Mag. 280, 1794. • Aspidosperma tomentosum: Martius, Nova Gen. et Spec. Pl. Brasiliensium (1824). • Cascabela gaumeri, as Thevetia: Hook. Ic. Pl. 16 (1886). • Chilocarpus torulosus, as C. anguineus: Hook. Ic. Pl. 30 (1913). • Clitandra cymulosa, as C. orientalis: Hook. Ic. Pl. 28 (1902). • Dipladenia atropurpurea: Bot. Reg. 29 (27), 1843. • Dipladenia crassinoda: Bot. Reg. 1844, 64. • Diplorhynchus condylocarpon, as D. mossambicensis: Hook. Ic. Pl. 14 (1880–82). • Echites stellaris: Bot. Reg. 1664, 1835. • Lacmellea utilis, as Zschokkea: Hook. Ic. Pl. 27 (1900). • Lepinia solomonensis: Hook. Ic. Pl. 28 (1901). • Leuconotis griffithii, as L. elastica: Hook. Ic. Pl. 28 (1902). • Mandevilla suaveolens: Bot. Reg. xxvi, 7 (1840). • Melodinus cochichinensis, as M. moniogynus: R. Wight, Ic. Pl. Indiae Orientalis 2 (1843). • Pachypodium succulentum: as P. tuberosum, Bot. Reg. 1321, 1830. • Pachypodium succulentum: Bot. Mag. 91 (1865). • Prestonia mollis: Humboldt et al., Nova Genera et Species Plantarum 3 (1819). • Rauwolfia tetraphylla, as R. heterophylla: Hook. Ic. Pl. 4 (1841). • Strophanthus kombe: Hook. Ic. Pl. 11 (1867–71). • Vinca major: Eng. Bot. 905 (1866). • Vinca minor (B. Ent., 1826). • Vinca minor: Eng. Bot. 906 (1866). • Wrightia coccinea: Bot. Mag. 53, 2696 (1826). • Leaf hairs of Echites and Oncinotis (Solereder, 1908).

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: 15th April 2018.’.