Peharec P., Posilović H., Balen B., Krsnik-Rasol M., Spine micromorphology of normal and hyperhydric Mammillaria gracilis Pfeiff. (Cactaceae) shoots, Journal of Microscopy, 2010, 239(1):78-86, doi: 10.1111/j.1365-2818.2009.03358.x
Stereomicroscopy and scanning microscopy compare the spines of greenhouse, normal in vitro and hyperhydric Mammillaria gracilis shoots. Cultured spines are shorter and have longer epidermal cell projections than greenhouse material. The paper documents areole and spine surface structure, and disturbed spine arrangement on hyperhydric shoots.