In this study, seeds of 5 species of Acanthophyllum in Turkey were examined with stereomicroscope and scanning electron microscope (SEM) to evaluate the systematic significance of seed microstructure. The seeds of Acanthophyllum were characterised by oblong or obovate shape. Seeds dorsal and ventral side are generally convex. The largest seeds are found in A. acerosum (2.45 mm in length and 1.16 mm in width). The smallest seeds are found in A. verticillatum (1.61 mm in length and 0.84 mm in width). Seeds surface of Acanthophyllum species are fine tuberculate arranged with elongate or polygonal cells like jigsaw puzzle. The shape of suture is sinuous, undulate or dentate. The colour of seed is reddish-brown or yellowish-brown. The radicle is on the one side of each seed and just out beyond the hilar notch. Colour of seeds, seed length and width, hilum length and width, suture shape, testa cell shape and the number of suture points per plate are important characters in differentiating Acanthophyllum species. By this study, similarities and differences between the species of Acanthophyllum genus are revealed and contributed to taxonomic studies.