Spontane bastaarden bij Duizendguldenkruid (Centaurium Hill) in Nederland: Centaurium erythraea x littorale en C. littorale x pulchellum

The identification of Centaurium plants is sometimes difficult, partly because of the occurrence of hybrids, partly because of the insufficient set of diagnostic characters. The new diagnostic characters presented here are: form of the stigma / length of the pedicel / presence of papillae on pedicel and calyx / form of the ‘true’ stem leaves / length of the corolla lobes / relative length of the corolla tube in fruit / size and ornamentation of the seed. With this set of characters a number of deviating herbarium species could be selected. Most probably they must be regarded as hybrid specimens of C. erythraea x littorale or C. littorale x pulchellum, or of backcrosses of these primary hybrids with one of their parents. Remarkably, on the island of Schiermonnikoog true C. erythraea is absent while the hybrid C. erythraea x littorale x is now demonstrated to occur (thusfar unnoticed) since 1867. All collections from the Wadden Sea islands Terschelling and Schiermonnikoog of “C. littorale var. latifolium” sensu Freysen 8 belong to this hybrid