A cross-section through part of a bamboo skewer, showing a vascular bundle (looking like a monkey face), surrounded by cells of the bundle sheath.
The large holes ('eyes') are the xylem pores which carry water from the underground rhizome to the leaves. The 'nose' pores are the phloem which bring the carbohydrates manufactured in the leaves down to the the stem and rhizome.
The solid material above and below these pores are fibres which give the cane its great strength.
Original image by Roger Heady. This image has been colour-enhanced.