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The families of flowering plants

L. Watson and M. J. Dallwitz

Gentianaceae Juss.

Including Chironiaceae Horan.; excluding Saccifoliaceae.

Habit and leaf form. Herbs (mostly, often with dichotomous branching), or shrubs (a few); non-laticiferous. Leaves well developed, or much reduced. Plants autotrophic, or saprophytic. Annual, or biennial; with a basal aggregation of leaves, or without conspicuous 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. Leaf development not ‘graminaceous’.

General anatomy. Plants with ‘crystal sand’ (rarely, in Gentiana and Sabbatia).

Leaf anatomy. The leaf lamina dorsiventral, or bifacial. Abaxial epidermis commonly papillose. Mucilaginous epidermis present, or absent. Stomata present; anomocytic (commonly), or anisocytic. Hairs infrequent, but sometimes manifest as uniseriate, bicellular or unicellular trichomes or shaggy hairs. Adaxial hypodermis present (sometimes mucilaginous), or absent. Lamina without secretory cavities. The mesophyll containing mucilage cells (or even consisting of mucilaginous cells), or not containing mucilage cells; containing crystals, or without crystals (and rarely with crystal sand). The crystals druses, or solitary-prismatic. Minor leaf veins without phloem transfer cells (4 genera).

Axial (stem, wood) anatomy. Young stems cylindrical, or oval in section. Nodes unilacunar, or tri-lacunar, or multilacunar; exhibiting on either side a trace which divides, contributing the outermost lateral traces to each of the opposite leaves (represented in species of Enicostema, Faroa and Lisianthus), or without split-lateral traces. Primary vascular tissues in a cylinder, without separate bundles (usually), or comprising a ring of bundles, or comprising two or more rings of bundles (the vascular systems of saprophytes and semi-saprophytes variously represented by open or almost closed rings of centric, collateral or bicollateral bundles in various combinations); for the most part bicollateral. Internal phloem present (as a continuous ring, or as isolated strands inside the vascular bundles, sometimes also with medullary phloem strands). Cortical bundles absent. Medullary bundles present (commonly, developing from medullary phloem strands), or absent. Secondary thickening absent, or developing from a conventional cambial ring, or anomalous. The anomalous secondary thickening when present, from a single cambial ring. Primary medullary rays narrow (uniseriate, or absent).

The vessel end-walls simple. The axial xylem with libriform fibres. ‘Included’ phloem present (very commonly), or absent.

Reproductive type, pollination. Plants hermaphrodite (usually), or polygamomonoecious (rarely); homostylous, or heterostylous. Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes. The ultimate inflorescence units 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 irregularity (when manifest) involving the perianth (K only), or involving the perianth and involving the androecium. Flowers 4–5(–12) merous; cyclic; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. 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 blunt-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); not fleshy.

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; in the same series as the fertile stamens. Stamens (1–)4–5(–12); inserted near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube; 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 (4 genera), or 3-celled (4 genera).

Gynoecium 2 carpelled. The pistil 1 celled, or 2 celled (rarely). Gynoecium 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, phytochemistry. Anatomy non-C4 type (Blackstonia). Cyanogenic (sometimes), or not cyanogenic. Iridoids detected; ‘Route I’ type (normal and seco). Saponins/sapogenins doubtfully present, or absent. Proanthocyanidins absent. Ellagic acid absent (2 genera, 3 species). Aluminium accumulation demonstrated (in a few genera). Sieve-tube plastids S-type.

Special distinguishing feature. Lamina tip not abaxially pouched (i.e., not as in Saccifoliaceae).

Geography, cytology. Frigid zone to tropical. Cosmopolitan. X = 5–13(+).

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae; Gentianales. Cronquist’s Subclass Asteridae; Gentianales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order 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, 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.

Illustrations. • Technical details: Gentiana, Erythraea = Centaurium. • Centaurium, Gentiana, Gentianella, Blackstonia (B. Ent. compilation, 1824–35). • Blackstonia perfoliata (as Chlora perfoliata): Eng. Bot. 913 (1866). • Centaurium erythraea (as Erythraea centaurium: Eng. Bot. 909 (1866). • Chironia peduncularis: Bot. Reg. 1803, 1836. • Gentiana acaulis: Bot. Mag. 2, 1788. • Gentiana pneumonanthe: Eng. Bot. 914 (1866). • Gentiana verna: Eng. Bot. 915 (1866). • Orphium frutescens: Bot. Mag. 2, 1788.

Quotations

Who bade the sun
Clothe you with rainbows? Who, with living flowers
Of loveliest blue, spread garlands at your feet?
(Coleridge, ‘To Chamouni’ - alluding to gentians)


The descriptions are offered for casual browsing only. We strongly advise against extracting comparative information from them. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 22nd August 2016. delta-intkey.com’.

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