Sparganiaceae Schultz-Schultzenst.
Habit and leaf form. Marsh or aquatic herbs. Perennial; with neither basal nor terminal aggregations of leaves; rhizomatous. Hydrophytic to helophytic; rooted, or free floating (a few). Leaves emergent and floating. Leaves alternate; distichous; sessile; sheathing; simple. Lamina entire; linear; parallel-veined; without cross-venules. Leaves with a persistent basal meristem, and basipetal development (?).
General anatomy. Plants with silica bodies. Accumulated starch exclusively ‘pteridophyte type’.
Leaf anatomy. Stomata present; paracytic.
The mesophyll containing mucilage cells (with raphides), or not containing mucilage cells; containing calcium oxalate crystals. The mesophyll crystals raphides, or druses, or solitary-prismatic. Minor leaf veins without phloem transfer cells. Vessels present; end-walls scalariform.
Stem anatomy. Secondary thickening absent. Xylem with vessels. Vessel end-walls scalariform. Sieve-tube plastids P-type; type II.
Root anatomy. Root xylem with vessels. Vessel end-walls scalariform.
Reproductive type, pollination. Fertile flowers functionally male and functionally female. Plants monoecious (the inflorescence system basally female, apically male). Floral nectaries absent (? — no septal nectaries). Anemophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The terminal inflorescence unit racemose. Inflorescences axillary; of globose units, each comprising twice- thrice-compound heads. Flowers bracteate (female flowers, usually), or ebracteate (male flowers, usually); small; regular to very irregular (according to the location in the inflorescence). The floral irregularity involving the perianth and involving the androecium. Flowers cyclic. Floral receptacle developing an androphore. Perigone tube absent.
Perianth of ‘tepals’; (1–)3–4(–6); free; 1 whorled, or 2 whorled; isomerous, or anisomerous; sepaloid (scaly).
Androecium (1–)3(–6) (depending on position in the inflorescence). Androecial members free of the perianth; free of one another, or coherent (filaments sometimes fused basally); 1 whorled, or 2 whorled. Androecium exclusively of fertile stamens. Stamens (1–)3(–6); reduced in number relative to the adjacent perianth to diplostemonous. Anthers basifixed; non-versatile; extrorse (when ascertainable); tetrasporangiate. Microsporogenesis successive. Tapetum amoeboid. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; ulcerate (the aperture diffusely delimited); 2-celled.
Gynoecium 1 carpelled, or 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled, or 2 celled. Gynoecium monomerous, or syncarpous (in the latter case, pseudomonomerous, with one locule empty); of one carpel, or synovarious to synstylovarious; superior. Carpel apically stigmatic; 1 ovuled. Placentation apical. Ovary when detectably syncarpous, 2 locular. Gynoecium stylate. Styles 2; free to partially joined; attenuate from the ovary. Stigmas dry type; papillate; Group II type. Placentation when pseudomonomerous, apical. Ovules 1 per locule; pendulous; anatropous; bitegmic; crassinucellate. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; proliferating (forming up to 150 cells); ephemeral. Synergids pear-shaped. Endosperm formation helobial. Embryogeny onagrad.
Fruit fleshy to non-fleshy. The fruiting carpel indehiscent; drupaceous, or nucular. Fruit when detectably pseudomonomeric or syncarpous, indehiscent; a drupe, or a nut. The drupes with one stone. Fruit 1 seeded. Seeds endospermic. Endosperm oily. Perisperm present (thin). Seeds with starch. Cotyledons 1. Embryo achlorophyllous (1/1); straight. Testa without phytomelan; very thin.
Seedling. Hypocotyl internode present (short). Mesocotyl absent. Seedling collar not conspicuous. Cotyledon hyperphyll elongated; assimilatory; more or less circular in t.s. Coleoptile present. Seedling cataphylls absent. First leaf dorsiventral. Primary root ephemeral.
Physiology, biochemistry. Not cyanogenic. Alkaloids present, or absent. Proanthocyanidins present; cyanidin. Flavonols present; quercetin and myricetin. Ellagic acid absent. Saponins/sapogenins absent. C3. C3 physiology recorded directly in Sparganium. Anatomy non-C4 type (Sparganium).
Geography, cytology. Frigid zone and temperate, or tropical (a few). Widespread North temperate, also Southeast Australia and New Zealand - and a few in Borneo and New Guinea. X = 15.
Taxonomy. Subclass Monocotyledonae. Superorder Bromeliiflorae; Typhales. APG (1998) Monocot; Commelinoid group; Poales. Species 20. Genera 1; only genus, Sparganium.
Illustrations. • Sparganium emersum. • Technical details (Sparganium).
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).
