Figure 1 from: Gebauer R, Řepka R, Šmudla R, Mamoňová M, Ďurkovič J (2016) Anatomical and morphological spine variation in Gymnocalycium kieslingii subsp. castaneum (Cactaceae). PhytoKeys 69: 1-15. https://doi.org/10.3897/phytokeys.69.8847

Figure 1 - Measured spine traits: spine width (Sw) and spine thickness (Sth). Fibers are shown in the detailed picture.