The families of flowering plants
Habit and leaf form. Low shrubs, or herbs. Plants succulent (commonly, more or less), or non-succulent. Without conspicuous aggregations of leaves. Mainly strand plants. Leaves alternate to opposite (alternate below, those towards the inflorescence sometimes in alternate pairs of unequal members towards the same side of the stem, cf. many Solanaceae); herbaceous, or leathery (sometimes small and ericoid), or fleshy; petiolate to sessile; non-sheathing; simple. Lamina entire. Leaves exstipulate.
General anatomy. Plants with crystal sand.
Leaf anatomy. The leaf lamina dorsiventral, or centric. Stomata present; mainly confined to one surface, or on both surfaces; tending to anisocytic. Hairs present; eglandular and glandular (the latter always multicellular and iniseriate, either simple or branched; the latter with stalks comprising one or two cells and uni- or multi-cellular, ellipsoidal heads).
Axial (stem, wood) anatomy. Primary vascular tissues bicollateral. Internal phloem always present. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow (uniseriate).
The vessel end-walls simple. The axial xylem with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres. Included phloem absent.
Reproductive type, pollination. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the disk.
Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; somewhat irregular to very irregular; at least somewhat zygomorphic. The floral irregularity involving the androecium, or involving the perianth and involving the androecium. Flowers 5 merous; cyclic; basically tetracyclic. Free hypanthium absent. Hypogynous disk commonly present; intrastaminal (around the base of the ovary); annular (crenate or lobulate).
Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous; blunt-lobed; campanulate and tubular; unequal but not bilabiate to regular (? the lobes often unequal); persistent (ultimately enclosing the fruit); imbricate (slightly, usually), or valvate (seldom). Corolla 5; 1 whorled; gamopetalous; plicate (between the lobes); campanulate, or funnel-shaped; obscurely bilabiate, or regular, or unequal but not bilabiate; white, or pink, or blue.
Androecium 5. Androecial members adnate; markedly unequal (three longer than the other two); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; inserted near the base of the corolla tube; isomerous with the perianth; oppositisepalous; alternating with the corolla members. Anthers dehiscing via longitudinal slits; introrse. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or decussate. Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate; 2-celled.
Gynoecium (3–)5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil if syncarpous, 5 celled. Gynoecium apocarpous (often, ostensibly), or syncarpous; eu-syncarpous, or synstylous (the carpels of Alona are united to form a conventional 5-locular, superior ovary with a terminal style, but in Nolana they are (a) 5, largely distinct by transverse constrictions and united only by the gynobasic style, (b) presented in a cycle of 10 portions by further transverse constrictions, or (c) presented in 1030 portions in two or three rows, by both longitudinal and transverse constrictions); superior. Ovary unconventionally divided into mericarps or 5 locular. Locules each divided horizontally into one-ovulate locelli, or not horizontally divided. Gynoecium median, or transverse (presumably without the obliquity characteristic of Solanaceae?); stylate. Styles 1; apical (Alona), or gynobasic (usually, in an extreme form). Stigmas 1; capitate, or peltate; wet type; papillate; Group III type. Ovules ascending (or appendiculate); hemianatropous; unitegmic; tenuinucellate (with an integumentary tapetum). 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 cellular. Endosperm haustoria absent. Embryogeny solanad.
Fruit non-fleshy; an aggregate, or not an aggregate; fundamentally, ontogenetically(?) a schizocarp. Mericarps 5, or 10–30 (in 13 rows); comprising nutlets (these 17 seeded). Seeds endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2. Embryo curved, or coiled.
Seedling. Germination phanerocotylar.
Physiology, phytochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins absent (Nolana). Flavonols present; kaempferol and quercetin. Ellagic acid absent.
Geography, cytology. Neotropical. Temperate to tropical. West coastal South America, Peru to Patagonia. X = 12.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgrens Superorder Solaniflorae; Solanales. Cronquists Subclass Asteridae; Solanales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Solanales (as a synonym of Solanaceae).
Species 85. Genera 2; Alona, Nolana.
General remarks. Differing clearly from Solanaceae only in the medianly or transversely orientated, 5-locular ovary and schizocarpic fruit, also (on the evidence of limited sampling) in the lack of endosperm haustoria.
Illustrations. • Le Maout and Decaisne: Nolana. • Alona, Aplocarya and Nolana: Lindley. • Alona coelestis: Bot. Reg. 1844, 46.
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: 9th January 2018. delta-intkey.com/angio’.