Habit and leaf form. Low shrubs, or herbs. Plants succulent (commonly, more or less), or non-succulent. With neither basal nor terminal 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. Stomata present; tending to anisocytic.
Lamina dorsiventral, or centric.
Stem anatomy. Internal phloem present. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres. Vessel end-walls simple. Primary medullary rays narrow (uniseriate).
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 10–30 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 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 1–3 rows); comprising nutlets (these 1–7 seeded). Seeds endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2. Embryo curved, or coiled.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. 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. Dahlgren’s Superorder Solaniflorae; Solanales. Cronquist’s 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.
• Technical details: Nolana.
• Technical details: Alona, Nolana (Lindley).
• Alona coelestis: Bot. Reg. 1844, 46.