The ontogenetic development and morphological properties of spores and vesicular-arbuscular mycorrhizae of Glomus trimurales (Glomerales), a fungus recovered from maritime sand dunes of northwestern Poland, are presented. This species had not been recorded previously in Poland and Europe. Spores of G. trimurales from Poland are yellowish-white to golden-yellow and have one wall comprising three layers: a hyaline to orange-white outermost layer ornamented with thickenings or blister-like outgrowths, a yellowish-white to golden-yellow, smooth or slightly wrinkled, rigid middle layer, and a hyaline, laminated innermost layer consisting of easily stratifying sublayers. No spore wall layers of G. trimurales stain in Melzer's reagent. Mycorrhizae formed by this fungus in one-species cultures with Plantago lanceolata consisted of arbuscules, vesicles, as well as intra- and extramatrical hyphae staining darkly in trypan blue. The properties of G. trimurales revealed are compared with those given in the original description of this fungus and those observed in preserved spores of a voucher material. Additionally, the know distribution of this fungus in the world is presented.