The trichome on the left has no secretory head. Look carefully at its tip and notice that it looks diffuse, indistinct whereas the side walls are cut cleanly. The trichome was not lying parallel to the plane of sectioning, so the microtome knife cut it at an angle. At the time of sectioning, the left trichome might have had a secretory head just like the right one. Or it might have been a little older and have abscised its head once it had finished secreting (see Fig. 10.33 on page 191 in Plant Anatomy (Mauseth)). Another possibility is that the left trichome is a completely different type from the right one: many plants with secretory trichomes also have non-glandular ones as well. |