Family Apocynaceae
General anatomy. Plants with laticifers (non-articulated, branched or unbranched). The laticifers in leaves and in stems. Leaf anatomy. Epidermis with crystal idioblasts (sometimes), or without crystal idioblasts. Stomata anomocytic, or paracytic. Lamina dorsiventral (usually), or isobilateral (rarely); with secretory cavities, or without secretory cavities (?). The mesophyll with sclerencymatous idioblasts (‘spicular cells’), or without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells (Dipladenia, Trachelospermum, Vinca). Stem anatomy. Secretory cavities present, or absent (?). Cork cambium present; initially deep-seated (rarely), or superficial. Nodes unilacunar. Primary vascular tissue bicollateral. Internal phloem usually present. Secondary thickening developing from a conventional cambial ring, or anomalous; from a single cambial ring. ‘Included’ phloem present (Lyonsia), or absent. Xylem with tracheids; with fibre tracheids, or without fibre tracheids; with vessels. Vessel end-walls simple, or scalariform (with few bars). Vessels with vestured pits. Wood parenchyma apotracheal (usually), or paratracheal (in a few genera). Sieve-tube plastids S-type. Reproductive type, pollination. Unisexual flowers absent. 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 unit 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, biochemistry. Cyanogenic (rarely), or not cyanogenic (mostly). Alkaloids present (mostly), or absent. Iridoids detected (in three genera); ‘Route II’ type (b), or ‘Route I’ type and ‘Route II’ type (doubtfully). Verbascosides not detected. 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. Saponins/sapogenins present, or absent. Aluminium accumulation demonstrated (a few genera only), or not found (mostly). Sugars transported as sucrose, or as oligosaccharides + sucrose, or as sugar alcohols + oligosaccharides + sucrose. 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). Geography, cytology. Temperate (a few), or sub-tropical to tropical (mainly). Widespread. X = 8–12(+). Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae; Gentianales. Cronquist’s Subclass Asteridae; Gentianales. APG (1998) Eudicot; core Eudicot; Asterid; Euasterid I. APG 3 (2009) 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, 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. 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. Quotations |
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