Organogenic nodule formation in hop. A Detail of a transversal section of a nodule after 45 days in culture showing one shoot bud (sb) connected to the nodular vascular bundles. Material was previously embedded in paraffin wax. B. Nodule cluster (nc) formed after 45 days in culture and showing several shoot buds and plantlets (pl). Bars in A = 150 μm, in B = 800 μm.