Family Stylidiaceae
Stylidiaceae R. Br.Including Candolleaceae Schönl.Excluding Donatiaceae Habit and leaf form. Herbs, or shrubs (or shrublets). ‘Normal’ plants, or switch-plants (occasionally); sometimes with the principal photosynthesizing function transferred to stems (E.g., the rush-like S. junceum). Leaves well developed (usually), or well developed and much reduced (commonly with basal leaves, and scales above), or absent (occasionally). Perennial; with a basal aggregation of leaves (often), or with terminal aggregations of leaves (often with cauline rosettes), or with neither basal nor terminal aggregations of leaves; rhizomatous, or tuberous. Self supporting (mostly), or climbing (rarely); when scandent, scrambling (Stylidium scandens, via leaf tips recurved into hooks). Helophytic (in bogs), or mesophytic to xerophytic. Leaves alternate (usually, conspicuously so), or whorled (Stylidium scandens); spiral; ‘herbaceous’, or leathery; imbricate; subsessile; sheathing; simple. Lamina entire; linear (grasslike); parallel-veined; without cross-venules. Leaves exstipulate. Leaf anatomy. Hydathodes present (occasionally), or absent. Lamina dorsiventral. The mesophyll containing mucilage cells; without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells (Stylidium). Stem anatomy. Internal phloem present. Secondary thickening anomalous; from a single cambial ring. ‘Included’ phloem present. Xylem with fibre tracheids. Wood partially storied (VI). Reproductive type, pollination. Plants hermaphrodite, or monoecious, or polygamomonoecious, or dioecious (?). Pollination entomophilous; mechanism conspicuously specialized (in Stylidium the stylar column springs violently from one side when triggered so as to deposit pollen on a visiting insect, while in Levenhookia the column is immobile but the hooded labellum springs so as to cause shedding of pollen). Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes, in racemes, in spikes, and in corymbs. The ultimate inflorescence unit cymose, or racemose. Inflorescences scapiflorous (often), or not scapiflorous; terminal. Flowers bracteate; small to medium-sized; very irregular; resupinate to not resupinate. The floral irregularity involving the perianth and involving the androecium, or involving the androecium (occasionally the corolla almost regular). Flowers 5 merous; cyclic; pentacyclic. Floral receptacle developing an androphore (the peculiar ‘stylar column’, which bears the stigma and the anthers at its tip, sometimes being thus interpreted), or with neither androphore nor gynophore (if the column is interpreted as a gynostemium). Free hypanthium present. Perianth with distinct calyx and corolla; (7–)10(–12); 2 whorled; isomerous (usually), or anisomerous. Calyx (2–)5(–7); 1 whorled; polysepalous, or gamosepalous; bilabiate (usually); imbricate; with the median member posterior. Corolla 5 (though often ostensibly only 4, with two pairs of conspicuous lobes); 1 whorled; appendiculate (in the throat, or the labellum appendaged), or not appendiculate; gamopetalous; imbricate (and resupinate or partly so); unequal but not bilabiate (the anterior member different from the others, forming a ‘labellum’, often much smaller and/or otherwise different from the rest), or regular; white, or pink, or purple. Androecium 2. Androecial members free of the perianth; united with the gynoecium (seemingly forming an often irritable column with the style, the stigma and stamens borne at its tip); coherent; 1 adelphous (via the gynostemium); 1 whorled (posterior-lateral). Androecium exclusively of fertile stamens. Stamens 2(–3); reduced in number relative to the adjacent perianth. Anthers dehiscing via longitudinal slits; extrorse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with one middle layer; of the ‘dicot’ type. Tapetum glandular. Pollen grains aperturate; 3–8 aperturate; colpate; 2-celled. Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled, or 2 celled. Gynoecium syncarpous (but sometimes pseudomonomerous by abortion); eu-syncarpous; inferior. Ovary 2 locular (usually), or 1 locular (by abortion of the posterior locule). Gynoecium median. Epigynous disk present, or absent. Styles 1. Stigmas dry type; papillate; Group II type. Placentation when both locules fertile axile. Ovules in the single cavity when only one locule fertile 1, or 4; 15–50 per locule (‘many’); pendulous, or horizontal, or ascending; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; persistent. Synergids elongated, hooked (and sometimes with filiform apparatus). Endosperm formation cellular. Endosperm haustoria present (aggressive); chalazal and micropylar. Embryogeny solanad. Fruit fleshy to non-fleshy; dehiscent, or indehiscent (rarely); a capsule; 4–100 seeded (‘few to many’). Seeds endospermic. Endosperm oily. Seeds minute. Cotyledons 2. Seedling. Germination phanerocotylar. Physiology, biochemistry. Not cyanogenic. Alkaloids absent (3 species). Iridoids detected; ‘Route I’ type. Proanthocyanidins present (normal and seco). Flavonols present, or absent; kaempferol and quercetin. Ellagic acid absent (2 species of Stylidium). Saponins/sapogenins present (rarely), or absent. Aluminium accumulation not found. Inulin recorded. Geography, cytology. Temperate to tropical. Southeast Asia, Malaysia, Australia, New Zealand, southernmost South America. N = 15, 18. Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Cornales. Cronquist’s Subclass Asteridae; Campanulales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Asterales. Species 150. Genera 5; Fostera, Levenhookia, Oreostylidium, Phyllachne, Stylidium. Illustrations. |
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