2. Schenkia Grisebach, Bonplandia (Hannover). 1: 226. 1853.
[I]
Centaury [For Joseph August Schenk, 1815–1891, (Austrian-) German botanist and palaeontologist]
James S. Pringle
Herbs annual or biennial, chlorophyllous, glabrous. Leaves basal and cauline, opposite. Inflorescences spikelike [racemoid], monochasial cymes, sometimes dichasial at base. Flowers 5-merous; calyx lobed nearly to base; corolla pink to rose-violet, salverform, glabrous, lobes abruptly spreading, elliptic-oblong, shorter than [± as long as] tube, margins entire or erose-tipped, plicae between lobes absent; stamens inserted in or near corolla sinuses, diverging radially; anthers distinct, coiling helically at dehiscence; ovary sessile; style deciduous, erect, distinct, not cleft; stigmas 2, [1, 2-lobed]; nectaries absent. Capsules ellipsoid. x = 11.
Species 5 (1 in the flora): introduced, Massachusetts; Eurasia, n Africa, Pacific Islands, Australia; temperate to dry-mesic tropical regions.
G. Mansion (2004) and Mansion and L. Struwe (2004) inferred from molecular studies that Schenkia is more closely related to Zeltnera and the European Exaculum Caruel than to Centaurium in the narrow sense. The stigma morphology of Schenkia is similar to that of Zeltnera.
Schenkia differs from Centaurium and Zeltnera most distinctly in its spicate inflorescences, although the inflorescence of S. spicata is often dichasial at the one or two most proximal divisions. Conversely, the inflorescences of some Zeltnera species, such as Z. muehlenbergii, are distally monochasial with the pedicels short or none. Although Schenkia generally differs from Zeltnera in having the stamens inserted in rather than below the sinuses of the corolla, S. spicata varies in this respect, sometimes having the stamens inserted slightly below the sinuses (G. Mansion 2004).
