a Cross-section of a petiole of C. grandiflora, stained with astra blue and safranin (3:2). The bicollateral vascular bundles are arranged in a U-shape b Trichome on the adaxial ridge of a cross-section of a petiole of C. grandiflora. Although not visible by naked-eye, the petiole is also covered with few-celled glandular trichomes c Young plant of C. adoensis var. jeffreyana. The trichomes are mainly occurring on the prominent veins. The adaxial side of the petiole bears smaller trichomes on the ridges, which fade into the leaf margin.