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Issue: Vol. 776 No. 2: 24 Sept. 2026
Type: Article
Published: 2026-09-24
DOI: 10.11646/phytotaxa.776.2.2
Page range: 147-165
Abstract views: 14
PDF downloaded: 0

Comparative stem anatomy and its taxonomic significance in eleven Galium (Rubiaceae) taxa from Türkiye

Department of Pharmaceutical Botany; Faculty of Pharmacy; Cukurova University; 01130; Adana; Türkiye
Department of Pharmaceutical Botany; Faculty of Pharmacy; Anadolu University; 26470; Eskisehir; Türkiye
Eudicots Galium stem anatomy Rubiaceae taxonomy taxonomic characters

Abstract

The stem anatomy of eleven Galium taxa (G. setaceum, G. spurium subsp. spurium, G. aparine, G. rotundifolium, G. odoratum, G. rivale, G. humifusum, G. verum subsp. verum, G. incanum subsp. elatius, G. album subsp. pycnotrichum, and G. paschale) representing eight sections of the genus was comparatively investigated using light microscopy. Considerable variation was observed in stem outline, trichome characteristics, collenchyma development, cortical organization, vascular tissues, pith structure, ray seriation, and the occurrence of secretory ducts and raphides. The combination of these characters provided useful diagnostic information at sectional, species, and subspecific levels. Among the studied taxa, G. odoratum was distinguished by its characteristic plus-shaped stem, localized collenchyma, and discontinuous endodermal ring. G. setaceum was characterized by a relatively wide xylem and a narrow, solid pith, whereas G. aparine and G. rotundifolium, despite sharing a quadrangular stem and chlorenchymatic cortex, differed in pith structure, collenchyma development, secretory ducts, and ray seriation. Galium incanum subsp. elatius was distinguished by the combination of dense trichomes, a micropapillate cuticle, and raphides, while G. album subsp. pycnotrichum differed from G. paschale in stem outline, trichome development, and cuticular ornamentation. The anatomical differences observed among taxa representing sect. Jubogalium, sect. Kolgyda, sect. Platygalium, sect. Hylaea, sect. Orientigalium, sect. Trachygalium, sect. Galium, and sect. Leiogalium indicate that stem characters can provide complementary evidence for taxonomic identification and delimitation within Galium. However, because the present study was not designed to test sectional relationships or monophyly, the anatomical characters are considered primarily diagnostic rather than phylogenetic. These findings highlight the potential of stem anatomy as a complementary character system in the comparative taxonomy of Galium.

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How to Cite

Kalas, M. & Kaya, A. (2026) Comparative stem anatomy and its taxonomic significance in eleven Galium (Rubiaceae) taxa from Türkiye. Phytotaxa 776 (2): 147–165. https://doi.org/10.11646/phytotaxa.776.2.2