Phenotypic plasticity in leaf morphology of Crataegus monogyna (Rosaceae): an experimental study with taxonomic implications

Many leaf characters are considered in the taxonomy of Crataegus in Europe, and several have been used in studies of the extent of hybridization in populations of northwest Europe. In such analyses it is assumed that the environmental component of phenotypic variation in such characters is insignificant. We tested this assumption by analysing the variation in the size and shape of leaves borne on clone cuttings of Crataegus monogyna maintained under identical conditions apart from the availability of soil nutrients. The resulting variation among leaves from this single genotype was as great as that observed previously across populations. Furthermore, although most of this variation could not be explained, a part could be attributed to differences in nutrient availability; of nine leaf characters investigated, eight showed significant variation due to this source, and in seven, the variation covaried significantly with nutrient level. The systematic implications of this are briefly explored.     

The "Nordstrom suture" to enhance scalp reductions

The authors compared the results of 10 scalp reductions using the "Nordstrom suture" with the earlier published results of scalp reductions without a device to prevent stretch-back and of reductions with extenders. At 1 month postoperatively, the Nordstrom suture eliminated the stretch-back of 8.3 mm seen in earlier studies and, in fact, it shrank the bald area. The average shrinking achieved with the Nordstrom suture was 16.9 mm (i.e., 143 percent improvement over scalp reductions alone). Scalp extenders shrank the bald area, but the Nordstrom suture shrank the area about three times more than extenders at 1 month postoperatively.