• Korean Journal of Plant Taxonomy
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• v.48 no.3
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• pp.185-194
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• 2018

A comparative floral morphological study of 19 taxa in Persicaria sect. Cephalophilon with four taxa related to Koenigia was conducted to evaluate the taxonomic implications. The flowers of P. sect. Cephalophilon have (four-)five-lobed tepals; five, six, or eight stamens, and one pistil with two or three styles. The size range of each floral characteristic varies according to the taxa; generally P. humilis, P. glacialis var. glacialis and Koenigia taxa have rather small floral sizes. The connate degrees of the tepal lobes and styles also vary. The tepal epidermis consists of elongated rectangular cells with variation of the anticlinal cell walls (ACWs). Two types of glandular trichomes are found. The peltate glandular trichome (PT) was observed in nearly all of the studied taxa. The PT was consistently distributed on the outer tepal of P. sect. Cephalophilon, while Koenigia taxa and P. glacialis var. glacialis had this type of trichome on both sides of the tepal. P. criopolitana had only long-stalked pilate-glandular trichomes (LT) on the outer tepal. The nectary is distributed on the basal part of the inner tepal, with three possible shapes: dome-like, elongated, and disc-like nectary. The nectaries are always accompanied by elongated or spheroidal papillae. Various combinations of floral characters (e.g., the numbers of stamens and styles, the stigma shape, the nectary shape, ACWs, cuticular striation and the trichome type and distribution) of P. sect. Cephalophilon are useful when attempting to recognize the infrasectional levels of P. sect. Cephalophilon recently proposed. Here, we describe the floral characteristics in detail and discuss the taxonomic significance of the floral characters.