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The families of flowering plants

L. Watson and M.J. Dallwitz

Commelinaceae R. Br.

Excluding Cartonemataceae.

Habit and leaf form. Herbs. Plants succulent and non-succulent. Annual, or perennial; with a basal aggregation of leaves, or without conspicuous aggregations of leaves. Young stems often breaking easily at the nodes. Self supporting, or epiphytic, or climbing; stem twiners, or root climbers. Stem growth not conspicuously sympodial. Mesophytic, or helophytic. Leaves evergreen; alternate; spiral, or distichous; more or less fleshy (often), or ‘herbaceous’; petiolate, or sessile; sheathing. Leaf sheaths with joined margins. Leaves simple. Lamina entire; parallel-veined. Leaves eligulate. Lamina margins entire. Vernation involute, or plicate (rarely).

General anatomy. Plants with silica bodies, or without silica bodies.

Leaf anatomy. Epidermis without differentiation into ‘long’ and ‘short’ cells; containing silica bodies (in several genera), or without silica bodies. Guard-cells not ‘grass type’. The mesophyll containing mucilage cells (or mucilage canals, with raphides); containing crystals. The crystals raphides. Foliar vessels present; with simple end-wall perforations. Minor leaf veins without phloem transfer cells (Tradescantia).

Axial (stem, wood) anatomy. Young stems cylindrical, or oval in section. Primary vascular tissues consisting of scattered bundles. Cortical bundles absent. Secondary thickening absent.

The vessel end-walls simple.

Root anatomy. Root xylem with vessels; vessel end-walls simple.

Reproductive type, pollination. Plants hermaphrodite, or andromonoecious, or dioecious. Floral nectaries absent (nectaries lacking). Pollination autogamous or entomophilous (but without nectar); mechanism conspicuously specialized (with dimorphic stamens comprising concolourous fertilizing members, and specialised, bright yellow ‘food stamens’ attractive to pollinators but producing little pollen. Moniliform hairs on the filaments may further delude visitors by simulating pollen), or unspecialized.

Inflorescence, floral, fruit and seed morphology. Flowers solitary (rarely), or aggregated in ‘inflorescences’; in cymes. The ultimate inflorescence units cymose. Inflorescences often a cincinnus; with involucral bracts, or without involucral bracts. Flowers regular, or somewhat irregular to very irregular. The floral irregularity when present, involving the perianth, or involving the androecium, or involving the perianth and involving the androecium. Flowers cyclic. Perigone tube absent.

Perianth with distinct calyx and corolla; 6; free, or joined (then the inner tepals basally connate); 2 whorled; isomerous; different in the two whorls; blue, or violet, or purple, or white, or yellow (rarely). Calyx 3; 1 whorled; polysepalous, or gamosepalous (the sepals rarely connate basally). Calyx lobes when gamosepalous, markedly longer than the tube. Calyx regular. Corolla 3; 1 whorled; polypetalous (usually), or gamopetalous (rarely); regular, or unequal but not bilabiate (sometimes with one petal different in colour and more or less reduced); blue, or purple, or white, or yellow (rarely). Petals clawed, or sessile.

Androecium 6 (usually — 3+3), or 3, or 1 (rarely). Androecial members free of the perianth; free of one another; usually 2 whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes 1–3. Stamens (1–)3, or 6; reduced in number relative to the adjacent perianth, or isomerous with the perianth, or diplostemonous. Anthers dorsifixed, or basifixed; versatile, or non-versatile; dehiscing via pores, or dehiscing via longitudinal slits; appendaged, or unappendaged. The anther appendages when present, representing expanded connective. Endothecium developing fibrous thickenings. The endothecial thickenings girdling. Anther epidermis persistent. Microsporogenesis successive. The initial microspore tetrads isobilateral, or decussate. Pollen grains aperturate; 1 aperturate (usually), or 2–4 aperturate; mostly sulcate; 2-celled (7 genera).

Gynoecium 3 carpelled. The pistil (1–)3 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; superior. Ovary 3 locular (usually), or 1–3 locular (sometimes apically one-locular, or 1–2 locules undeveloped). The ‘odd’ carpel (where ascertainable) anterior. Styles 1; apical. Stigmas wet type, or dry type; papillate, or non-papillate; Group II type, Group III type, and Group IV type. Placentation axile. Ovules 1–50 per locule (i.e. to ‘many’); ascending; arillate; orthotropous to hemianatropous; bitegmic; crassinucellate (mostly), or pseudocrassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Polygonum-type, or Allium-type, or Adoxa-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral, or persistent. Endosperm formation nuclear. Embryogeny asterad.

Fruit fleshy (rarely), or non-fleshy; dehiscent, or indehiscent (rarely); usually a capsule. Capsules loculicidal. Seeds copiously endospermic. Endosperm not oily (mealy). Seeds with starch. Cotyledons 1, or 2 (the second sometimes present, vestigial). Embryo achlorophyllous (1/1). Testa operculate (in the form of a characteristic callosity, the ‘embryostega’, covering the embryo); without phytomelan.

Seedling. Hypocotyl internode present (sometimes long), or absent (e.g. Cyanotis). Mesocotyl absent. Seedling collar conspicuous (in the form of the periblast), or not conspicuous. Cotyledon hyperphyll elongated (then downwardly directed), or compact. Coleoptile present (often), or absent. First leaf dorsiventral. Primary root ephemeral.

Physiology, phytochemistry. C3 and CAM. C3 physiology recorded directly in Commelina, Cyanotis, Tradescantia, Zebrina. CAM recorded directly in Tradescantia, Tripogandra. Anatomy non-C4 type (Commelina, Cyanotis, Tradescantia, Zebrina). Accumulated starch other than exclusively ‘pteridophyte type’. Cyanogenic (rarely), or not cyanogenic. Cynogenic constituents tyrosine-derived. Alkaloids present (occasionally), or absent. Saponins/sapogenins present (Cyanotis), or absent (usually?). Proanthocyanidins present, or absent; when present, cyanidin. Ellagic acid absent. Aluminium accumulation not found. Sieve-tube plastids P-type; type II.

Geography, cytology. Mostly sub-tropical and tropical. Widespread, mostly tropical and subtropical. X = (4–)6–16(–29).

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Commeliniflorae; Commelinales. APG 3 core angiosperms; Superorder Lilianae; commelinid Monocot; Order Commelinales.

Species 500. Genera 38; Aetheolirion, Amischotolpe, Aneilema, Anthericopsis, Belosynapsis, Buforrestia, Callisia, Cochliostema, Coleotrype, Commelina, Cyanotis, Dichorisandra, Dictyospermum, Elasis, Floscopa, Geogenanthus, Gibasis, Gibasoides, Matudanthus, Murdannia, Palisota, Pollia, Polyspatha, Porandra, Pseudoparis, Rhoeo, Rhopalephora, Sauvallea, Siderasis, Spatholirion, Stanfieldiella, Streptolirion, Thyrsanthemum, Tinantia, Tradescantia, Tricarpelema, Tripogandra, Weldenia.

Economic uses, etc. Includes a few well known garden ornamentals and houseplants.

Illustrations. • Le Maout and Decaisne: Tradescantia, Commelina. • Aneilema beniniense: Thonner. • Callisia warszewicziana, as Tradescantia: Bot. Mag. 86 (1860). • Cyanotis beddomei, as Erythrotis: Bot. Mag. 101 (1875). • Dichorisandra saundersii: Bot. Mag. 101 (1875). • Spironema fragrans: Bot. Reg. xxvi, 47 (1840). • Tinantia erecta: as Tradescantia undata, Bot. Reg. 1403 (1831).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 24th October 2017.’.