Habit and leaf form. Herbs (mostly, often with dichotomous branching), or shrubs (a few). Leaves well developed, or much reduced. Autotrophic, or saprophytic. Annual, or biennial; with a basal aggregation of leaves, or with neither basal nor terminal aggregations of leaves. Climbing (Crawfurdia ~ Gentiana p.p.), or self supporting (usually). Helophytic, or mesophytic (often alpine). Leaves opposite (and decussate, usually), or whorled (rarely - Swertia), or alternate (seldom); rarely (i.e. when alternate) spiral; `herbaceous', or membranous (in mycotrophic species); petiolate to sessile; connate (often), or not connate (but then often connected by a transverse line); simple; epulvinate. Lamina entire; pinnately veined, or palmately veined. Leaves exstipulate (but the opposing leaf bases sometimes connected by a transverse line). Lamina margins usually entire. Leaves without a persistent basal meristem.
Leaf anatomy. Abaxial epidermis commonly papillose. Mucilaginous epidermis present, or absent. Stomata present; anomocytic (commonly), or anisocytic.
Adaxial hypodermis present (sometimes mucilaginous), or absent. Lamina dorsiventral, or isobilateral; without secretory cavities. The mesophyll containing mucilage cells (or even consisting of mucilaginous cells), or not containing mucilage cells. Minor leaf veins without phloem transfer cells (4 genera).
Stem anatomy. Nodes unilacunar, or tri-lacunar, or multilacunar. Primary vascular tissue centrifugal, or bicollateral (often). Cortical bundles absent. Medullary bundles present (commonly), or absent. Internal phloem present. Secondary thickening developing from a conventional cambial ring, or anomalous (Gentianoideae); from a single cambial ring. `Included' phloem present (commonly), or absent. Xylem with libriform fibres; with vessels. Vessel end-walls simple. Sieve-tube plastids S-type.
Reproductive type, pollination. Hermaphrodite (usually), or polygamomonoecious (rarely); plants homostylous, or heterostylous. Entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in `inflorescences'; in cymes. The terminal inflorescence unit (when flowers aggregated) nearly always cymose. Inflorescences terminal, or axillary; usually a simple or compound dichasium. Flowers bracteate, or ebracteate; bracteolate, or ebracteolate; small, or medium-sized; regular, or somewhat irregular to very irregular. The floral asymmetry (when manifest) involving the perianth (K only), or involving the perianth and involving the androecium. Flowers 4-5(-12) merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present, or absent; when present, of separate members, or annular.
Perianth with distinct calyx and corolla; 8-10(-24); 2 whorled; isomerous. Calyx 4-5(-12); 1 whorled; polysepalous (rarely), or gamosepalous; entire (occasionally), or lobulate, or lobed (or polysepalous); regular, or bilabiate (rarely); imbricate (usually), or open in bud (sometimes). Epicalyx present, or absent. Corolla 4-5(-12); 1 whorled; appendiculate (often with scales or nectary pits inside), or not appendiculate; gamopetalous; contorted (commonly), or imbricate; campanulate, or funnel-shaped, or cyathiform, or rotate, or hypocrateriform; regular; white, or pink, or purple, or blue (often showy).
Androecium 4-5(-12) (as many as C). Androecial members adnate (to the tube); all equal, or markedly unequal (sometimes declinate); free of one another (usually), or coherent (forming a tube in some saprophytic genera); 1 - whorled. Androecium exclusively of fertile stamens (nearly always), or including staminodes. Staminodes when present, 1-4. Stamens (1-)4-5(-12); isomerous with the perianth (nearly always), or reduced in number relative to the adjacent perianth (very occasionally with some stamens staminodal or wanting); oppositisepalous. Anthers dorsifixed (usually), or basifixed; versatile (when dorsifixed), or non-versatile; dehiscing via longitudinal slits, or dehiscing via pores (rarely via apical pores); usually introrse; tetrasporangiate; appendaged (sometimes, with glands), or unappendaged. Endothecium developing fibrous thickenings (usually), or not developing fibrous thickenings (rarely, e.g. Cotylanthera). Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall of the `dicot' type. Tapetum amoeboid, or glandular. Pollen polysiphonous, or monosiphonous; shed in aggregates (Helieae), or shed as single grains; when aggregated, in tetrads. Pollen grains aperturate; (1-)2 - aperturate, or 3(-4) - aperturate; porate (and sometimes ruporate), or colporate; 2-celled, or 3-celled.
Gynoecium 2; syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 1 locular (usually), or 2 locular (rarely). Gynoecium median, or transverse; stylate, or non-stylate (Lomatogonium, with stigmas decurrent along the sides of the ovary). Styles usually 1; attenuate from the ovary; apical. Stigmas 1, or 2; 1 - lobed, or 2 - lobed; wet type; papillate; Group III type. Placentation parietal (usually), or free central (rarely); rarely, when bilocular axile. Ovules in the single cavity when unilocular, 15-100 (i.e. `many'); when ovary bilocular, 15-50 per locule (i.e. `many); horizontal; non-arillate; anatropous (usually), or orthotropous (e.g. Leiphaimos); unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; proliferating (e.g. Swertia), or not proliferating; usually ephemeral. Synergids pear-shaped. Endosperm formation cellular, or nuclear. Embryogeny solanad.
Fruit fleshy (rarely), or non-fleshy; dehiscent (usually), or indehiscent (rarely); a capsule (usually), or a berry (rarely). Capsules septicidal. Seeds usually copiously endospermic (but scantily so in saprophytic forms). Endosperm oily. Seeds winged, or wingless. Embryo rudimentary at the time of seed release to weakly differentiated (in saprophytes), or well differentiated. Cotyledons when developed, 2. Embryo chlorophyllous (Swertia iberica), or achlorophyllous (2/2); straight.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Cyanogenic (sometimes), or not cyanogenic. Iridoids recorded; seco-compounds. Proanthocyanidins absent. Ellagic acid absent (2 genera, 3 species). Saponins/sapogenins present (doubtfully), or absent. Aluminium accumulation demonstrated (in a few genera). Anatomy non-C4 type (Blackstonia).
Geography, cytology. Frigid zone to tropical. Cosmopolitan. X = 5-13(+).
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren's Superorder Gentianiflorae; Gentianales. Cronquist's Subclass Asteridae; Gentianales. Takhtajan's Subclass Asteridae; Gentiananae; Gentianales. Species 900. Genera about 80; Bartonia, Belmontia, Bisgoeppertia, Blackstonia, Canscora, Celiantha, Centaureum, Chironia, Chorisepalum, Cicendia, Comastoma, Congolanthus, Cotylanthera, Coutoubea, Cracosna, Crawfurdia, Curtia, Deianira, Djaloniella, Enicostema, Eustoma, Exaculum, Exacum, Faroa, Frasera, Geniostemon, Gentiana, Gentianella, Gentianopsis, Gentianothamnus, Halenia, Hockinia, Hoppea, Irlbachia, Ixanthus, Jaeschkea, Karina, Latouchea, Lehmanniella, Lisianthius, Lomatogoniopsis, Lomatogonium, Macrocarpaea, Megacodon, Microrphium, Monodiella, Neblinantha, Neurotheca, Obolaria, Oreonesion, Ornichia, Orphium, Parajaeschkea, Prepusa, Pterygocalyx, Pycnosphaera, Rogersonanthus, Sabatia, Schinziella, Schultesia, Sebaea, Senaea, Sipapoantha, Swertia, Symbolanthus, Symphyllophyton, Tachia, Tachiadenus, Tapeinostemon, Tetrapollinia, Tripterospermum, Urogentias, Veratrilla, Voyria, Voyriella, Wurdackanthus, Zonanthus, Zygostigma.
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