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; cross-venulate. Leaves exstipulate. Lamina margins entire.
Leaf anatomy. The leaf lamina dorsiventral. Stomata present; mainly confined to one surface (abaxial); anomocytic (occasionally), or paracytic (usually). The mesophyll with spherical etherial oil cells. Minor leaf veins without phloem transfer cells.
Axial (stem, wood) anatomy. Young stems with solid internodes. Pith homogeneous (but with the central cells thinner-walled). Nodes unilacunar (with one trace). Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.
The wood diffuse porous. The vessels very to moderately small; solitary. The vessel end-walls reticulately perforated and scalariform. The axial xylem with tracheids; including septate fibres. The parenchyma sparse paratracheal. Included phloem absent. The wood not storied. Tyloses present.
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.
Perianth sequentially 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).
Seedling. Germination phanerocotylar.
Physiology, phytochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins present; cyanidin and delphinidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent. Sieve-tube plastids S-type.
Geography, cytology. Holarctic, Paleotropical, and Neotropical. Sub-tropical to tropical. Tropical Southeast Asia, North America, West Indies. X = 13, 14.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Magnoliiflorae; Illiciales. Cronquists Subclass Magnoliidae; Illiciales. APG 3 peripheral angiosperms; Superorder Austrobaileyanae; Order Austrobaileyales (as a synonym of Schisandraceae?).
Species 42. Genera 1; only genus, Illicium.
General remarks. Apart from details of leaf and wood anatomy relying on limited sampling, this compilation shows Illicium differing from Schizandraceae (q.v.) in habit, sexuality of the flowers, and details of androecium and gynoecium morphology.
Economic uses, etc. Some cultivated ornamentals, and commercial volatile oil from I. verum.
Illustrations. • Illicium floridanum: Bot. Mag. 439 (1897). • Carpel, fruit and seed: Illicium.
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: 13th March 2017. delta-intkey.com/angio’.