Stylidiaceae R. Br.
Including Candolleaceae Schönl.
Excluding Donatiaceae
Habit and leaf form. Herbs, or shrubs (or shrublets). 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 (?). Entomophilous. Pollination mechanism characteristically conspicuously specialized (the stylar column springing forcibly from one side when triggered), or unspecialized (Levenhookia).
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes, in racemes, in spikes, and in corymbs. The terminal 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; 1 whorled; gamopetalous; imbricate (and resupinate or partly so); unequal but not bilabiate (the anterior member often forming a ‘labellum’, often 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 a column with the style, the stigma and stamens borne at the tip of the column); 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; 3-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 (1998) Eudicot; core Eudicot; Asterid; Euasterid II; Asterales. Species 150. Genera 5; Fostera, Levenhookia, Oreostylidium, Phyllachne, Stylidium.
Illustrations. • Technical details (Stylidium).
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).
