The families of flowering plants
~ Xanthorrheaceae-Xanthorrhoeoideae p.p. of APG III.
Excluding Anthericaceae, Asphodelaceae, Calectasiaceae, Dasypogonaceae, Hemerocallidaceae.
Habit and leaf form. Shrubs, or arborescent (the habit characteristic, with a trunk up to 2 m, or almost acaulescent); resinous. With a basal aggregation of leaves (when acaulescent), or with terminal aggregations of leaves; rhizomatous, or tuberous. Self supporting. Pachycaul. Xerophytic. Leaves evergreen; small to very large; alternate; spiral; leathery; sessile; sheathing (initially), or non-sheathing (subsequently). Leaf sheaths not tubular; with free margins. Leaves simple. Lamina entire; linear; parallel-veined; without cross-venules.
Leaf anatomy. Stomata present; paracytic. Lamina with secretory cavities. Secretory cavities containing resin. The mesophyll containing crystals. The crystals solitary-prismatic. Foliar vessels present; with scalariform end-walls. Minor leaf veins without phloem transfer cells (1 genus).
Axial (stem, wood) anatomy. Secretory cavities present; with resin (this yellow, red or brown). Primary vascular tissues consisting of scattered bundles. Secondary thickening anomalous. The anomalous secondary thickening from a single cambial ring. The axial xylem with vessels, or without vessels.
The vessel end-walls scalariform.
Root anatomy. Root xylem with vessels; vessel end-walls simple.
Reproductive type, pollination. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the gynoecium (from septal nectaries).
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences. Inflorescences scapiflorous; terminal; complex, dense, spikelike, multiflorous, pedunculate. Flowers bracteate; bracteolate; small; regular; 3 merous; cyclic; pentacyclic. Perigone tube absent. Hypogynous disk absent.
Perianth of tepals; 6; free; 2 whorled; isomerous; sepaloid (or bractlike); different in the two whorls (the outer members stiffer and shorter). Tepal apex trichomes (TAT) present.
Androecium 6. Androecial members free of the perianth; all equal; free of one another; 2 whorled. Androecium exclusively of fertile stamens. Stamens 6; diplostemonous. Anthers dorsifixed; dehiscing via longitudinal slits; introrse. The endothecial thickenings spiral. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate.
Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 3 locular. Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stylar canal present. Stigmas 1; trilobate, capitate or punctiform. Placentation axile. Ovules 3–8 per locule (a few); horizontal, or ascending; non-arillate; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type.
Fruit non-fleshy; dehiscent; a capsule (woody or cartilaginous). Capsules loculicidal. Fruit 3–6 seeded. Seeds endospermic. Endosperm oily. Cotyledons 1. Embryo straight, or curved (situated transversely). Testa encrusted with phytomelan; black.
Seedling. Seedling collar not conspicuous. Cotyledon hyperphyll elongated; more or less circular in t.s. Coleoptile absent. First leaf dorsiventral. Primary root ephemeral.
Physiology, phytochemistry. Not cyanogenic. Anthraquinones detected; polyacetate derived. Proanthocyanidins present (a trace only, in one of the two species screened), or absent; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent.
Geography, cytology. Australian. Temperate to tropical. Australia. X = 22.
Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Asparagales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Asparagales.
Species 66. Genera 1; only genus, Xanthorrhoea.
General remarks. The lumping of Asphodelaceae, and Dasypogonaceae (q.v.) in an expanded version of Xanthorrhoeaceae on supposedly phylogenetic grounds appears fairly reasonable in terms of the comparative data compiled for this package; but Hemerocallidaceae differ in 30 characters, representing habit, general morphology and anatomy.
Illustrations. • Xanthorrhoea preissii: Bot. Mag. 13 (1887). • Xanthorrhoea: habit and flower (Chittenden).
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: 12th September 2017. delta-intkey.com/angio’.