(American Journal of Botany. ;91:0.)
© Botanical Society of America, Inc.
Seasonalgreen
Tessier presents new information on the leaf production and dynamics of a temperate understory herb, Oxalis acetosella, censused over two years in a northern hardwood forest of the Catskill Mountains, New York, USA. The term ``wintergreen'' has been used to describe the species' leaf habit in which one yearly set of leaves is produced in the spring and overwinters. Tessier found a more complicated dynamic: plants maintain leaves throughout the year, but with varying numbers of leaves by season, with average leaf life span less than one year, and with a summer peak in leaf number=ma habit he terms "seasonalgreen."
(see p. 1371)
Dorota Kwiatkowska in the Invited Special Paper in this issue reviews current biomechanical theory about cell wall alignment, as it might apply to the shoot apical meristem (SAM). She focuses on anisotropic factors, such as the mechanical properties of cell walls, that participate in the integration of SAM cell activities. The article juxtaposes several independently pursued lines of investigation on apical meristems and demonstrates how they interact, overlap, or converge as parts of one body of information. Further, it bridges the old and the new, and shows the relevance of classical studies to those that are more contemporary.
(see p. 1277)
Archibald et al. investigate hybridization and gene flow between day-flowering, long-proboscid fly-pollinated Zaluzianskya microsiphon and night-flowering, hawk moth-pollinated Z. natalensis. Apparent hybrids have been found in an area within the Kwazulu-Natal province of South Africa. Inter-simple sequence repeat (ISSR) markers and principal components analysis (PCA) provide data consistent with hybridization.
(see p. 1333)
A hybrid oak complex in Mexico is the subject of thorough analysis by Tovar-Sanchez and Oyama. The authors selected seven sympatric zones where intermediate individuals were known to exist and two additional sites where each parental species, Quercus crassifolia and Q. crassipes, occurred alone. In the mixed sites, they sampled 10 individuals from each parental species and 10 intermediate individuals. At the single-species sites, they sampled 10 trees in each of two locations. They then measured 17 morphological leaf characters and six RAPD genotypes for all individuals. Their extensive sampling of sites and variables and simultaneous measurement of morphological and genetic markers strengthen their conclusions.
(see p. 1352)
