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The families of flowering plants

L. Watson and M.J. Dallwitz

Nyctaginaceae Juss.

Including Allioniaceae Horan., Bougainvilleeae (Bougainvilleaceae) J.G. Agardh, Mirabilidaceae W.R.B. Oliv., Pisoniaceae J.G. Agardh

Habit and leaf form. Trees, shrubs, and herbs, or lianas (sometimes, e.g. Bougainvillea, Pisonia). Self supporting (mostly), or climbing (sometimes, in Pisonia). Mesophytic. Leaves alternate (sometimes), or opposite (usually, members of the pair often unequal); petiolate to sessile; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate.

General anatomy. Plants with ‘crystal sand’, or without ‘crystal sand’.

Leaf anatomy. The leaf lamina dorsiventral, or bifacial. Hairs present; eglandular and glandular; mostly multicellular. Multicellular hairs uniseriate; branched (e.g., in Pisonia), or simple. Complex hairs present (in Leucaster), or absent; stellate. The mesophyll usually containing crystals. The crystals raphides, or druses, or solitary-prismatic (but usually raphides or these mixed with styloids, druses seemingly rare). Minor leaf veins without phloem transfer cells (Bougainvillea, Oxybaphus, Pisonia).

Axial (stem, wood) anatomy. Cork cambium present; nearly always initially superficial. Nodes unilacunar. Primary vascular tissues comprising a ring of bundles, or comprising two or more rings of bundles; collateral. Internal phloem absent. Secondary thickening mostly anomalous. The anomalous secondary thickening mostly via concentric cambia (resulting in successive, sometimes irregular rings of collateral vascular bundles, which in woody species are sometimes embedded in prosenchymatous and lignified ground tissue). The axial xylem with vessels.

The vessels small (sometimes very small), or small to medium; typically in radial multiples and clustered (in groups of radial multiples and clusters internal to te phloem strands). The vessel end-walls simple (usually exclusively so), or reticulately perforated and simple (with rare horizontal, reticulate plates occurring in Boerhaavia and Bougainvillea). The axial xylem with libriform fibres. The parenchyma apotracheal, or paratracheal (usually very sparse). ‘Included’ phloem present (of the foraminate type, recorded in several genera), or absent. The wood partially storied (VP).

Reproductive type, pollination. Plants hermaphrodite (usually), or monoecious, or andromonoecious, or gynomonoecious, or polygamomonoecious (?).

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes, or in panicles, or in spikes, or in umbels. The ultimate inflorescence units usually cymose. Inflorescences terminal, or axillary; with involucral bracts (frequently, these often brightly coloured), or without involucral bracts; pseudanthial (sometimes, especially when reduced to a single flower — the involucre then calyx-like, the calyx corolla-like), or not pseudanthial. Flowers bracteate (usually with several bracts); small, or medium-sized; regular; usually cyclic; tricyclic. Free hypanthium absent. Hypogynous disk often present (around G); annular.

Perianth sepaline (but often very corolla-like); (3–)5(–10); joined; 1 whorled. Calyx (i.e. the perianth) (3–)5(–10); 1 whorled; gamosepalous; campanulate, or urceolate (rarely), or funnel-shaped, or tubular; regular; base persistent (and usually remaining around the fruit); valvate, or plicate in bud.

Androecium (1–)5(–30). Androecial members when numerous, maturing centrifugally; adnate (to the perianth tube, occasionally), or free of the perianth (usually); all equal, or markedly unequal; free of one another, or coherent; when coherent, 1 adelphous (the filaments basally connate); 1 whorled. Androecium exclusively of fertile stamens. Stamens (1–)5(–30); typically alternisepalous (i.e, alternating with the perianth); inflexed in bud. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with more than one middle layer (2); of the ‘basic’ type. Tapetum glandular. Pollen grains aperturate; 3(–4) aperturate, or 6–15 aperturate; colpate (3–4), or foraminate, or rugate (6-polyrugate); spinulose; 3-celled (in 4 genera).

Gynoecium 1 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel stylate; apically stigmatic, or with a lateral style; 1 ovuled. Placentation basal. Stigmas dry type; papillate; Group II type. Ovules ascending; non-arillate; campylotropous, or hemianatropous; unitegmic, or bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development usually Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; proliferating (sometimes, to a limited extent), or not proliferating; persistent. Synergids hooked. Endosperm formation nuclear. Embryogeny asterad.

Fruit non-fleshy. The fruiting carpel indehiscent; an achene, or nucular. Fruit usually enclosed in the persistent base of the perianth; 1 seeded. Seeds endospermic (the endosperm forming a cap over the radicle), or non-endospermic. Perisperm present. Seeds with starch. Embryo large, well differentiated. Cotyledons 2. Embryo chlorophyllous (2/2); curved (usually), or straight, or bent.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C3 and C4. C3 physiology recorded directly in Bougainvillea, Mirabilis. C4 physiology recorded directly in Allionia, Boerhaavia. Anatomy C4 type (Allionia, Boerhaavia, Okenia), or non-C4 type (Boerhaavia, Bougainvillea, Commicarpus, Mirabilis). Sugars transported as sucrose (Bougainvillea). Not cyanogenic. Alkaloids present, or absent. Iridoids not detected. Betalains present (where sought). Saponins/sapogenins present, or absent. Proanthocyanidins present, or absent; when present, cyanidin. Flavonols present; kaempferol, or kaempferol and quercetin (usually both, abundant). Ellagic acid absent (5 species, 4 genera). Plants often accumulating free oxalates. Sieve-tube plastids P-type; type III (a).

Geography, cytology. Temperate (a few), sub-tropical to tropical. Pantropical and subtropical. X = 10, 13, 17, 29, 33 (or more).

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Caryophylliflorae; Caryophyllales. Cronquist’s Subclass Caryophyllidae; Caryophyllales. APG III core angiosperms; core eudicot; Superorder Caryophyllanae. APG IV Order Caryophyllales.

Species 290. Genera 33; Abronia, Acleisanthes, Allionia, Ammocodon, Andradea, Anulocaulis, Belemia, Boerhavia, Bougainvillea, Caribea, Cephalotomandra, Colignonia, Commicarpus, Cryptocarpus, Cuscatlania, Cyphomeris, Guapira, Grajalesia, Izabalaea, Leucaster, Mirabilis, Neea, Neeopsis, Nyctaginia, Okenia, Phaeoptilum, Pisonia, Pisoniella, Ramisia, Reichenbachia, Salpianthus, Selinocarpus, Tripterocalyx.

Economic uses, etc. A few popular ornamentals, e.g. the annual Mirabilis and the subtropical vine Bougainvillea.

Illustrations. • Le Maout and Decaisne: Bougainvillea, Calpidia, Pisonia. • Bougainvillea glabra: Regel, Gartenflora 48 (1899). • Abronia, Mirabilis, Pisonia: Lindley. • Le Maout and Decaisne: Mirabilis. • Pisonia aculeata: Thonner. • Abronia fragrans: Bot. Mag. 91 (1865). • Pisonia cf. brunoniana, as P. sinclairii: Hooker, Fl. Novae-Zelandiae (1853). • Boerhavia schomburgkiana: Hook. Ic. Pl. 13 (1877–79). • Neea buxifolia, as Eggersia: Hook. Ic. Pl. 15 (1883). • Reichenbachia hirsuta: Hook. Ic. Pl. 13 (1877–79). • Leaf hairs and spongy mesophyll of Boerhavia and Pisonia (Solereder, 1908). • Pisonia nigricans: TS stem with medullary bundles (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.’.