(1647) Proposal to conserve the name Chrysanthemum coronarium (Compositae) with a conserved type

Abstract

The lectotype of Chrysanthemum coronarium L. 1753 is a specimen of the species currently known as Glebionis segetum (L.) Fourr. (based on C. segetum L. 1753). Therefore, C. coronarium is a taxonomic synonym of C. segetum, and the correct name for the species currently known as Glebionis coronaria (L.) Cass. ex Spach would be a new combination based on Pyrethrum indicum Sims 1813 non (L.) Cass. 1826. Undesirable nomenclatural disruption and confusion can easily be averted in this case by conserving the name C. coronarium with a conserved type. Among the 14 species of Chrysanthemum L. described by Linnaeus in the first edition of Species Plantarum are two species of Mediterranean annual weeds: C. coronarium or crown daisy (Habitat in Creta, Sicilia) and C. segetum or com marigold (Habitat in Scaniae, Germania, Belgii, Anglia, Gallia agris). Although essentially Mediterranean elements, both species are nowadays naturalized far beyond their 'native' range. Indeed, C. segetum was a common segetal weed in northwestern Europe before the widespread use of modem agricultural herbicides. The two species are quite distinct: C. coronarium has leaves green, 2-pinnatisect, ray florets either yellow or white with a yellow base, and achenes of ray florets with an adaxial wing; C. segetum has leaves glaucous, irregularly incised-dentate, ray florets always deep yellow, and achenes of ray florets without an adaxial wing; in both species the disk florets are yellow. Until the late 1990s, both species were almost universally treated in the genus Chrysanthemum, first in a broad, polyphyletic sense of that genus with over 200 species, then in a narrow sense with only two Mediterranean species, C. coronarium and C. segetum, the former having been designated as the type by Green (Int. Bot. Congr. Cambridge, Nomencl. Prop. Brit. Bot.: 182. 1929). However, after Trehane (in Taxon 44: 439-441. 1995) successfully proposed the Asian species C. indicum L. 1753 (the florists' chrysanthemum) as the conserved type of Chrysanthemum (see Brummitt in Taxon 47: 443-444. 1998; Nicolson in Taxon 48: 375. 1999), the Linnaean generic name replaced Dendranthema (DC.) Des Moul. for the florists' chrysanthemum and the two Mediterranean species had to be known under the next earliest legitimate name, Glebionis Cass. 1826. The generic name Ismelia Cass. 1826 was published simultaneously for the NW African annual currently known as I. carinata (Schousb.) Sch. Bip. (= L versicolor Cass. 1826, a superfluous name for C. carinatum Schousb. 1800). Ismelia was maintained as a monospecific genus by Bremer & Humphries (in Bull. Nat. Hist. Mus. London, Bot. 23: 135-136. 1993) and Bremer (Asteraceae: 466. 1994), although Tzvelev (in Bot. Zhum. 84(7): 117. 1999) united it with Glebionis and established priority for the latter name under Art. 11.5.