Juvenile leaves

Count insect holes Insect herbivory. Each student examines ten juvenile leaves and ten adult form leaves, and counts insect holes in all of them. Since you work in teams of 2 or 3, each student handles only a few leaves of each type. (If time is limited, a smaller number might also suffice, as you will pool the data for the entire class. Obviously, the larger the class, the fewer leaves each student will have to study). Count holes in the leaf and damage at the edge separately, as insect species differ in their feeding patterns, and affect tree species differently. 

Relate numbers of insect holes to leaf area. Using a spreadsheet, compute numbers of insect holes per area. Since juvenile leaves are larger and have fewer insect holes, this will show any differences in insect herbivory even better. 

Try to smell a difference between the two types of leaves Place each of five juvenile leaves in five separate small paper bags with a sniffing hole. Put three adult leaves in each of five identical paper bags. (The larger number is to compensate for the smaller leaf size.) Each student sniffs each bag with the invisible leaf Since we know that juvenile leaves are supposed to be better defended, for each bag we have to answer the question Is this leaf of the juvenile or adult type (Data Sheet 16.5)... 

Figure 5. Temperature-survival plot of Coespeletia timotensis juvenile leaves at 50% damage. Error bars = SE. Data from Garcia-Varela and Rada, 2003, redrawn by author.

Dodd, I.C., Critchley, C., Woodall, G.S. Stewart, G. (1998). Photoinhibition in differently coloured juvenile leaves of Syzygium species. Journal of Experimental Botany, 49,1437-1445. 

Hughes, N.M., Morley, C.B. Smith, W.K. (2007). Coordination of anthocyanin decline and photosynthetic maturation in juvenile leaves of three deciduous tree species. New Phytologist, 175, 675-685. Hughes, N.M., Vogehnann, T.C. Smith, W.K. (2008). Optical effects of abaxial anthocyanin on absorption of red wavelengths by imderstorey species revisiting the back-scatter hypothesis. Journal of Experimental Botany, 59, 3435-3442. 

---