33. Dianthus Linnaeus, Sp. Pl. 1: 409. 1753. Gen. Pl. ed. 5, 191. 1754.
Pink, carnation, oeillet [Greek dios, divine, and anthos, flower, alluding to beauty or fragrance]
Richard K. Rabeler, Ronald L. Hartman
Herbs, perennial (D. armeria annual or biennial), sometimes mat-forming. Taproots stout, rhizomes (when present) slender or stout. Stems erect or ascending, simple or branched, terete or angled. Leaves connate proximally into sheath, petiolate (basal leaves) or sessile; blade 1-veined, linear or oblong to ovate, apex acute. Inflorescences terminal, open cymes, dense bracteate clusters or heads, or flowers solitary; bracts paired, herbaceous to scarious, or absent; involucel bracteoles 1-3 pairs, herbaceous or scarious. Pedicels erect in fruit. Flowers: sepals connate proximally into tube, 10-22 mm, tube green or reddish, 20-60-veined, ± cylindric, terete, commissures between sepals absent, lobes green or reddish, 3-8-veined, triangular to lanceolate, shorter than tube, margins white or reddish, mostly scarious, apex acute or obtuse; petals often pink or red, sometimes white or purple, sometimes spotted or with darker center, clawed, auricles absent, coronal appendages absent, blade apex dentate or fimbriate to 1/ 2 of length; nectaries at filament bases; stamens 10, adnate with petals to carpophore; filaments distinct; staminodes absent; ovary 1-locular; styles 2, filiform, 0.7-6 mm, glabrous proximally; stigmas 2, linear along adaxial surface of styles, papillate (30×). Capsules ovoid to cylindric, opening by 4 teeth; carpophore present. Seeds 40-100+, blackish brown, shield-shaped, dorsiventrally compressed, papillose-striate to papillate, marginal wing absent, appendage absent; embryo central, straight. x = 15.
Species ca. 320 (6 in the flora): n North America, Eurasia (Balkans to c Asia), Africa; introduced in North America (except D. repens), South America, Pacific Islands (Hawaii), possibly Australia.
Dianthus species have been popular garden subjects for years; there are now over 27,000 registered cultivar names (A. C. Leslie 1983 and 19 subsequent supplements). Although they are most popular in Great Britain, many species and cultivars are grown in North America. While some popular taxa (e.g., D. caryophyllus Linnaeus, clove pink, and the hybrids called D. ‘allwoodii', Allwood's pink) do not appear to escape and/or persist after cultivation, others do so readily. Five of the six species treated here are introduced and readily persist; D. repens is our only native species.
In spite of the popularity of Dianthus in horticulture, the genus requires a thorough study using modern methods. It is the second largest genus in the family (surpassed only by Silene) but there is no recent monograph or comprehensive infrageneric classification. The genus is sometimes divided into two subgenera [Dianthus and Carthusianastrum F. Williams; e.g., F. A. Pax and K. Hoffmann (1934c) and T. G. Tutin and S. M. Walters (1993)], corresponding to the division indicated in couplet one of the key below. Others, including M. Kuzmina (2002, 2003), have considered this an artificial separation.
Besides the six species treated here, five others have been collected at least once outside of cultivation in North America and could be expected elsewhere in the flora area. On the basis of bracteole length, one species would key near Dianthus deltoides, and four near D. plumarius. Dianthus chinensis Linnaeus, the rainbow pink, similar to D. deltoides but with four involucral bracteoles, a glabrous calyx, and basal leaves absent when the plants flower, was noted as “persisting” in Lambton County, Ontario (C. K. Dodge 1915). Dianthus sequieri Villars, with bracteoles over one-half as long as the calyx, is otherwise similar to D. plumarius but with broader leaves [2-5 versus 1(-2) mm] and dentate petals. It was collected along a roadside at Fort Saskatchewan, Alberta, in 1948, 1949, and 1950 (Turner 6416, ALTA, DAO; 7019, DAO; 7269, ALTA). Dianthus arenarius Linnaeus, similar to D. plumarius but with green leaves shorter than 4 cm and petal blades with a greenish central spot and divided over one-half their length, was reported as a garden escape near Ottawa, Ontario, in 1958. Dianthus sylvestris Wulfen, similar to D. plumarius but with green leaves and entire or toothed, glabrous petals, was found in a ditch near Hancock, Michigan, in 1982 (Rabeler 711, MICH, MSC), quite possibly an escape from cultivation. Dianthus gratianopolitanus Villars, a popular rock-garden plant similar to D. plumarius but with glaucous leaves shorter than 4.5 cm, petal blades divided less than one-fourth their length, and narrowly scarious sepal-lobe margins, was collected along a roadside near Berrie, Ontario, in 1973 (Reznicek 3640, MICH, TRT).