Family Juncaginaceae
Juncaginaceae Rich.Including Borboraceae Dulac (p.p.), Lilaeaceae Dum., Maundiaceae Nak., Triglochinaceae Dum. Habit and leaf form. Herbs; laticiferous (rarely — Lilaea), or non-laticiferous and without coloured juice. Perennial (usually), or annual; with a basal aggregation of leaves; rhizomatous, or tuberous, or bulbaceous (very rarely). Hydrophytic, or helophytic (sometimes halophytic); when hydrophytic, rooted. Leaves small, or medium-sized; alternate; spiral, or spiral to distichous (‘spirodistichous’); flat; sessile; sheathing. Leaf sheaths with free margins. Leaves edgewise to the stem, or with ‘normal’ orientation; simple; epulvinate. Lamina entire; linear (occasionally reduced to the sheath); parallel-veined. Leaves ligulate; stipulate, or exstipulate. Axillary scales present. Leaves with a persistent basal meristem, and basipetal development. General anatomy. Accumulated starch exclusively ‘pteridophyte type’. Leaf anatomy. Epidermis without differentiation into ‘long’ and ‘short’ cells. Stomata present; mostly paracytic. Lamina with secretory cavities (elongate canals). The mesophyll containing calcium oxalate crystals, or without calcium oxalate crystals. The mesophyll crystals druses (?), or solitary-prismatic (? — crystals few, no raphides). Minor leaf veins without phloem transfer cells (Triglochin). Vessels absent. Stem anatomy. Secondary thickening absent. Xylem without vessels. Root anatomy. Root xylem with vessels; vessel end-walls scalariform. Reproductive type, pollination. Unisexual flowers present. Plants dioecious, or polygamomonoecious. Pollination anemophilous. Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes and in spikes. The ultimate inflorescence unit racemose. Inflorescences scapiflorous; terminal; dense or sparse spikes and racemes. Flowers ebracteate; small; regular; 1 merous (Lilaea), or 2 merous, or 3 merous; cyclic. Perigone tube absent. Perianth of ‘tepals’ (there being one member outside each stamen or staminode), or absent (if the ‘tepals’ are interpreted as staminal appendages — cf. Potamogetonaceae); 6 (usually), or 3, or 4, or 1; free; 2 whorled (usually), or 1 whorled; isomerous; sepaloid; without spots, or spotted (Tetroncium); similar in the two whorls. Androecium 6 (usually), or 3 (when the inner whorl missing), or 8 (rarely), or 1 (rarely). Androecial members adnate (if the flower is interpreted as having a perianth); free of one another; 1 whorled, or 2 whorled ((4+4) 3+3 or 2+2, rarely only three or one). Androecium exclusively of fertile stamens, or including staminodes (alternate members sometimes sterile). Staminodes when present, 3, or 4. Stamens 3, or 6, or 8 (rarely); isomerous with the perianth, or diplostemonous; filantherous to with sessile anthers. Anthers dehiscing via longitudinal slits; extrorse; tetrasporangiate. Endothecium developing fibrous thickenings. The endothecial thickenings spiral. Anther epidermis persistent. Microsporogenesis successive. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with one middle layer, or initially with more than one middle layer. Tapetum amoeboid. Pollen grains nonaperturate; 3-celled (Lilaea). Gynoecium 6 carpelled, or 4 carpelled, or 1 carpelled. Carpels isomerous with the perianth. Gynoecium apocarpous, or syncarpous, or monomerous; eu-apocarpous to semicarpous, or synovarious (usually in two trimerous or dimerous whorls, the carpels usually adnate to the central axis but separating at maturity); superior. Carpel non-stylate, or stylate; apically stigmatic; 1 ovuled. Placentation basal (usually), or apical (Maundia). Gynoecium non-stylate, or stylate. Stigmas dry type; papillate; Group II type. Placentation basal to axile (usually), or apical (Maundia). Ovules 1 per locule; ascending (usually), or pendulous (Maundia); non-arillate; anatropous (usually), or orthotropous (Maundia); bitegmic; crassinucellate. Embryo-sac development Polygonum-type. Polar nuclei fusing only after one has been fertilized, or fusing simultaneously with the male gamete (?). Antipodal cells formed; 3; proliferating (Triglochin), or not proliferating (Lilaea); persistent (if only as vestiges). Synergids beaked. Endosperm formation nuclear. Embryogeny caryophyllad. Fruit non-fleshy; an aggregate, or not an aggregate. The fruiting carpels if apocarpous, or considered so, coalescing into a secondary syncarp to not coalescing. The fruiting carpel dehiscent, or indehiscent; a follicle, or an achene. Fruit if syncarpous, a schizocarp. Mericarps 4, or 6; comprising achenes, or comprising follicles. Seeds non-endospermic. Seeds with starch. Cotyledons 1. Embryo straight. Testa without phytomelan; thin. Seedling. Germination phanerocotylar. Hypocotyl internode absent. Seedling collar not conspicuous. Cotyledon hyperphyll elongated; assimilatory; more or less circular in t.s. Coleoptile absent. Seedling non-macropodous. Seedling cataphylls absent. First leaf centric. Primary root ephemeral. Physiology, biochemistry. Cyanogenic, or not cyanogenic. Cynogenic constituents tyrosine-derived (triglochinin). Alkaloids absent. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent. Saponins/sapogenins absent. Geography, cytology. Frigid zone to sub-tropical. Widespread North and South temperate and frigid. X = 6, 8, 9. Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Alismatiflorae; Zosterales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Alismatales. Species 25. Genera 4; Triglochin, Lilaea, Maundia, Tetroncium. Lilaea is retained here following Dahlgren, Clifford and Yeo 1985 — but recognition of the family Lilaeaceae would greatly improve this description. Illustrations. |
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