Revisiting Acantholimon wilhelminae Sect. Armeriopsis (Plumbaginaceae): Taxonomic Reassessment, Morphological Variation, and Updated Distribution

ABSTRACT Acantholimon wilhelminae was described in 1974 from northwestern Iran and has remained poorly known, with its taxonomic distinctness subsequently questioned because only A. bracteatum was observed at the type locality. Here, we reassess A. wilhelminae based on examination of type material and herbarium specimens, together with field observations and newly collected material from northwestern Iran. The newly examined populations reveal substantial intraspecific variation in inflorescence architecture and flower number, including both compact and more distantly arranged spikelets, up to 12 flowers per spikelet, and occasional zigzagging of the inflorescence axis. These variable features occur without appreciable variation in the principal diagnostic characters and are interpreted as intraspecific variation. Comparison with A. gabrieljanae , A. bracteatum , and A. cephalotes confirms the morphological distinctness of A. wilhelminae . The species is most closely allied to A. gabrieljanae , particularly in its spicate inflorescences and bracteole morphology, but differs in a combination of vegetative and stem characters, including substantially longer summer leaves and peduncles and thicker flowering stems; the flowering axis also remains intact and comparatively robust at the fruiting stage, unlike the fragile axis of A. gabrieljanae .