Fig.
9.3-3. Transverse section of stem of wormwood (Artemisia). The
duct in this wormwood stem is large, well-defined and easy to see. The
epithelium cells all have abundant, darkly-stained contents, indicating a high
concentration of cytoplasm and a low level of vacuolation. This is fairly strong
evidence that the epithelium cells themselves are secretory, but it is also
possible for secretory cells to be so vacuolate that they almost appear empty.
This type of duct is very common; you will encounter it in many species.