The families of flowering plants.
Habit and leaf form. Glabrous, small trees, or shrubs; bearing essential oils. Leaves evergreen; alternate; spiral (sometimes crowded towards the tips of the twigs); leathery; petiolate; non-sheathing; gland-dotted, or not gland-dotted; aromatic, or without marked odour; simple. Lamina entire; pinnately veined. Leaves exstipulate. Lamina margins entire.
Leaf anatomy. Stomata present; mainly confined to one surface (abaxial); anomocytic (occasionally), or paracytic (usually).
Lamina dorsiventral. The mesophyll with spherical etherial oil cells. Minor leaf veins without phloem transfer cells.
Stem anatomy. Nodes unilacunar (with one trace). Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with tracheids; with vessels. Vessel end-walls scalariform and reticulately perforated. Primary medullary rays narrow. Wood parenchyma paratracheal. Sieve-tube plastids S-type.
Reproductive type, pollination. Plants hermaphrodite.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’ (these two- or three-flowered). Inflorescences axillary (or supra-axillary). Flowers small; regular; partially acyclic. The perianth acyclic and the androecium acyclic (the perianth and stamens commonly arranged in several series, but spiral within each). Free hypanthium absent. Hypogynous disk absent.
Perianthsequentially intergrading from sepals to petals (the members of the outermost series small and bractlike or sepaloid, the inner members commonly larger and more petaloid), or sepaline (the inner members reduced and sometimes transitional with the stamens); 7–33; free; commonly in several series, spiral within each.
Androecium (4–)20–50. Androecial members maturing centripetally (?); free of the perianth; free of one another; spirally arranged, in (1–)several series. Androecium exclusively of fertile stamens, or including staminodes. Staminodes external to the fertile stamens ((when present) in the form of intermediates with the inner perianth members). Stamens (4–)15–50; filantherous (the filaments short and thick). Anthers adnate (the thecae lateral); non-versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with more than one middle layer. Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colpate (colpoidate); 2-celled.
Gynoecium (5–)7–15(–21) carpelled; apocarpous; eu-apocarpous (its members attached obliquely to the receptacle in a single cycle, this ontogenetically resolvable into a tight helix); superior. Carpel incompletely closed (being unsealed at the narrowed, stylar tip); stylate; with a decurrent stigma; 1 ovuled. Placentation ventral and nearly basal. Stigmas dry type; non-papillate. Ovules ascending; anatropous; bitegmic; crassinucellate. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; ephemeral. Endosperm formation cellular, or nuclear. Embryogeny asterad.
Fruit non-fleshy; an aggregate. The fruiting carpel dehiscent; a follicle (the cycle of follicles often spreading radially in a stellate pattern). Fruit 1 seeded. Seeds copiously endospermic. Endosperm oily. Embryo well differentiated (very small). Cotyledons 2. Embryo achlorophyllous (1/1).
Physiology, biochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins present; cyanidin and delphinidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent.
Geography, cytology. Holarctic, Paleotropical, and Neotropical. Sub-tropical to tropical. Tropical Southeast Asia, North America, West Indies. X = 13, 14.
Taxonomy.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Illiciales. Cronquist’s Subclass Magnoliidae; Illiciales. APG 3 peripheral angiosperms; Superorder Austrobaileyanae; Order Austrobaileyales (as a synonym of Schisandraceae?).
Species 42. Genera 1; only genus, Illicium.
Economic uses, etc. Some cultivated ornamentals, and commercial volatile oil from I. verum.
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