Anarthriaceae Cutler & Airy Shaw
Habit and leaf form. Rushlike herbs (the stems simple or branched, sometimes very compressed). Switch-plants; phyllodineous. With neither basal nor terminal aggregations of leaves; rhizomatous. Helophytic. Leaves alternate; distichous; sheathing; edgewise to the stem (stemlike); simple; with a persistent basal meristem, and basipetal development.
General anatomy. Plants without silica bodies. Chlorenchyma including ‘peg cells’.
Leaf anatomy. Stomata present; paracytic. Guard-cells ‘grass type’ (grasslike).
The mesophyll with sclerencymatous idioblasts; without calcium oxalate crystals. Vessels present.
Stem anatomy. Secondary thickening absent. Xylem with vessels. Vessel end-walls scalariform.
Reproductive type, pollination. Fertile flowers functionally male and functionally female, or functionally male, or functionally female. Unisexual flowers present. Plants monoecious (rarely), or dioecious. Gynoecium of male flowers absent. Floral nectaries absent (? — no septal nectaries). Pollination anemophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes, or in panicles; not in ‘spikelets’ (though the chaffy bracteoles and perianth can lend the small flowers a spikelike aspect). Inflorescences lax paniculate cymes. Flowers bracteate; bracteolate, or ebracteolate; regular; 3 merous; cyclic. Perigone tube absent.
Perianth of ‘tepals’; 6; free; 2 whorled; isomerous; sepaloid; similar in the two whorls (glumelike).
Androecium 3. Androecial members free of the perianth; free of one another, or coherent; when coherent, 1 adelphous (the filaments connate); 1 whorled. Androecium exclusively of fertile stamens. Stamens in male flowers, 3; isomerous with the perianth; oppositiperianthial. Anthers basifixed; latrorse; tetrasporangiate. The endothecial thickenings girdling. Pollen grains aperturate; 1 aperturate; ulcerate. The ulcus without an operculum; with an annulus. Interapertural exine scrobiculate. Interapertural interstitium columellate. Pollen grains 3-celled.
Gynoecium 3 carpelled. The pistil 3 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 3 locular. Styles free. Stigmas 3. Placentation apical. Ovules 1 per locule; pendulous; orthotropous; bitegmic; tenuinucellate. Embryo-sac development Polygonum-type. Synergids non-haustorial. Hypostase present (near the chalazal end).
Fruit non-fleshy; indehiscent; a nut. Seeds endospermic (the endosperm mealy). Seeds with starch. Testa without phytomelan.
Physiology, biochemistry. Flavonols present; quercetin, or kaempferol and quercetin (kaempferol in infloresences).
Geography, cytology. Temperate. South West Australia.
Taxonomy. Subclass Monocotyledonae. Superorder Commeliniflorae; Poales. APG (1998) Monocot; Commelinoid group. APG 3 (2009) Order: Poales.
Species 5. Genera 1; only genus, Anarthria.
• Anarthria prolifera: habit (photo).
• Anarthria prolifera: spikelets (photo).
• Anarthria prolifera: habitat (photo).