Cross section in a petiole of Xantosoma sagittifolium

Xanthosoma sagitifolium is an herbaceous, perennial,  tropical plant in Araceae family native to northern South America. This plant can reach 1 to 2m tall.has different common names such as taro, tannia, purple elelphant ear among others. It is one of the oldest cutivated crops in the world and was introduced as culture in different tropical regions in which they are widely cultivated for underground stems, tubers used in various meals. In West Africa it is the most consumed aroid.However, this plant is fast-growing herb that has escaped from cultivation and become invasive. The leaves are arrow-shaped with long petioles and wavy margins. It grows best in humid tropical rainforest climates and along stream banks and moist areas. This plant is a monocotyledon.

Cross sections have been made in samples collected in Geneva Botanical Garden, fixed in FAA and embedded in paraffin. The firs microphotograph below illustrates a section characterized by (1) an aerenchyma and (2) vascular bundles distributed (blue arrows) on different circles at periphery of the section and in its central parenchyma (aer). 

Part of the cross section with a vascular bundle (red arrow). From outside toward center of the section we have fibers, pem and xylem

Characteristics of this section : (1) aerenchyma typical of plants living in wet habitats; (2) vascular bundles distributed on several circles.