The families of flowering plants.
AlternativelyHaloragaceae R. Br.
IncludingCercodianae (Cercodiaceae) Juss., Halorrhageae (Halorrhagaceae) Lindl., Myriophylleae (Myriophyllaceae) Schultz-Schultzenst.Excluding Gunneraceae
Habit and leaf form. Herbs (mostly), or shrubs, or ‘arborescent’ (Haloragodendron). ‘Normal’ plants. Plants autotrophic. Stem growth not conspicuously sympodial (monopodial). Hydrophytic to helophytic, or mesophytic; the aquatics rooted. Leaves of hydrophytes submerged and emergent. Heterophyllous (aquatic members with submerged leaves dissected and emergent leaves more or less entire), or not heterophyllous (when not aquatic). Leaves alternate, or opposite, or whorled; when alternate, spiral; petiolate to sessile; non-sheathing; simple, or compound (very varied in form); epulvinate; when compound, pinnate. Lamina dissected, or entire; when simple/dissected, pinnatifid, or palmatifid (sometimes trifid); one-veined, or pinnately veined. Leaves exstipulate;becoming compound from primordial lobes.
Leaf anatomy. Minor leaf veins without phloem transfer cells (1 genus).
Stem anatomy. Primary vascular tissue greatly reduced in the aquatics. Secondary thickening absent, or developing from a conventional cambial ring. Vessel end-walls simple.
Reproductive type, pollination. Plants hermaphrodite, or monoecious, or polygamomonoecious. Pollination anemophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in spikes (commonly), or in corymbs (Loudonia), or in racemes. Inflorescences pseudanthial (at least, some forms sometimes considered so), or not pseudanthial. Flowers bracteolate (often), or ebracteolate; minute to small; regular (usually); (2–)4 merous; cyclic; tetracyclic, or pentacyclic. Free hypanthium absent.
Perianthwith distinct calyx and corolla, or sequentially intergrading from sepals to petals, or vestigial to absent; when present, 4, or 8; free; 2 whorled, or 1 whorled (C sometimes absent); isomerous. Calyx 2, or 4; 1 whorled; polysepalous; regular; persistent; valvate. Corolla when present, 2, or 4; 1 whorled; polypetalous; regular.
Androecium 8, or (3–)4. Androecial members free of the perianth; all equal; free of one another; 1 whorled, or 2 whorled. Androecium exclusively of fertile stamens. Stamens3–4, or 8; isomerous with the perianth, or diplostemonous; alternisepalous (when two-whorled), or oppositisepalous; filantherous (with rather large anthers). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; latrorse; tetrasporangiate; appendaged (apiculate), or unappendaged. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. Anther wall of the ‘monocot’ type. Pollen grains aperturate; colpate (sometimes rupoidate); 3-celled (in Myriophyllum).
Gynoecium (2–)3–4 carpelled. The pistil 1 celled, or 3–4 celled. Gynoecium syncarpous; synovarious; inferior. Ovary (1–)3–4 locular (partitions sometimes incomplete, pseudomonomeric in Glischrocaryon). Epigynous disk absent. Gynoecium stylate. Styles (2–)3–4 (feathery); free; apical. Stigmas dry type; papillate; Group II type. Placentation apical.Ovules in the single cavity (Glischrocaryon) 4; 1 per locule; pendulous; anatropous; bitegmic; crassinucellate. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; persistent. Synergids with filiform apparatus.
Fruit non-fleshy; indehiscent, or a schizocarp. Mericarps when schizocarpic, 2–4; comprising nutlets (e.g. Myriophyllum). Fruit when non-schizocarpic, a drupe, or a nut. The drupes with separable pyrenes, or with one stone. Seeds more or less copiously endospermic. Endosperm oily. Cotyledons 2. Embryo achlorophyllous (1/1); straight.
Physiology, biochemistry. Cyanogenic. Iridoids not detected. Proanthocyanidins present, or absent (Myriophyllum). Flavonols present; quercetin, or kaempferol and quercetin. Ellagic acid present (Haloragis, Myriophyllum). Saponins/sapogenins present (in Haloragis), or absent. Anatomy non-C4 type (Myriophyllum).
Geography, cytology. Temperate to tropical. Cosmopolitan. X often = 7.
Taxonomy.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Haloragales. Cronquist’s Subclass Rosidae; Haloragales. APG 3 core angiosperms; core eudicot; unplaced at Superordinal level; Order Saxifragales.
Species 120. Genera 8; Glischrocaryon, Gonocarpus, Haloragis, Haloragodendron,Laurembergia, (Loudonia), Meziella, Myriophyllum, Proserpinaca.
Economic uses, etc. Myriophyllym is used for ponds and aquaria, and important in limnological conservation.
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