Arbuscular mycorrhizal (AM) fungi are named such because when their hyphae penetrate the root cortex they form tree-like structures called arbuscules. These arbuscules are the site of nutrient exchange between plants and fungi. Some AM fungi also produce vesicles to accumulate storage products, so this association has also been referred as vesicular-arbuscular mycorrhiza. However, the colonization by AM fungi does not change the appearance of roots. These pictures show how we sample, stain and mount root pieces on slides to verify the presence of the structures produced by AM fungi under the microscope.
After staining and mounting, we are able to examine the roots under a microscope. The staining highlights the abuscules and vesicles in Liquidambar as shown in the images below.