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The families of flowering plants.                                                                                                                                                                

Xanthorrhoeaceae Dum.

                        

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~ Xanthorrheaceae-Xanthorrhoeoideae of APG III

ExcludingAsphodelaceae, Calectasiaceae, Dasypogonaceae, Hemerocallidaceae

Habit and leaf form. Shrubs, or ‘arborescent’ (the habit characteristic, the 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 calcium oxalate crystals. The mesophyll crystals solitary-prismatic. Minor leaf veins without phloem transfer cells (1 genus). Vessels present; end-walls scalariform.

Stem anatomy. Secretory cavitiespresent; with resin (yellow, red and brown). Primary vascular tissue in scattered bundles. Secondary thickening anomalous; from a single cambial ring. Xylem with vessels, or without vessels. 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.

Perianthof ‘tepals’; 6; free; 2 whorled; isomerous; sepaloid (or bractlike);different in the two whorls (the outer members stiffer and shorter).

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, biochemistry. Not cyanogenic. Arthroquinones 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.

 Illustrations:

  • Xanthorrhoea: habit and flower (Chittenden).
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