Matthew Velkey, Ph.D., Adjunct Lecturer, Department of Cell and Developmental Biology, University of Michigan Medical School
Some of the first studies of cells were done in plant tissues. This image shows a stem of the industrial hemp plant, Cannabis sativa, cut in cross-section, revealing the numerous vessels, made up of cells connected end-to-end, that transport nutrients and water. The section is NOT stained, so the colors present are due to natural pigments in the plant. The stem of a hemp plant contains an inner, woody pith, or hurd, made up of xylem vessels (red), which transport water. The outer layer, or bast, contains phloem vessels (aqua) that transport sugars made in the leaves. The bast fiber bundles (greenish-red bundles) located in the outer layer are very strong and are used to make hemp products such as textiles and rope. This subspecies of Cannabis has a relatively low concentration of tetrahydrocannabinol, the psychoactive component found in marijuana. In 2009, the Obama administration changed the policy on the use of medical marijuana. Fourteen states, including Michigan, have made it legal for patients with certain life-threatening diseases to use medical marijuana as a therapeutic alternative to traditional medications.