title: Patterns of diversity in leaves from canopies of Ginkgo biloba are revealed using Specific Leaf Area as a morphological character.
abstract: OBJECTIVE
  The difference reported in the literature for the Specific Leaf Area (SLA, cm(2)/g) of leaves on short- and long-shoots of Acer rubrum could mean that SLA can serve as a quantitative morphological trait. Our survey of SLA in canopies of Ginkgo biloba sampled a different clade of seed plants to investigate this morphological phenomenon. Such a survey in this dioecious taxon, and one in which a single canopy may have juvenile and reproductive portions, as well as one where canopies bear leaves of several shapes, examine these additional morphological factors as well as any long-shoot short-shoot differences.
  
  
  METHODS
  We measured SLA for a set of 642 dried leaves, a sampling across all morphological levels in canopies of large landscape specimens. The tabulated values were analyzed as distributions.
  
  
  RESULTS
  Populations of leaves of G. biloba, sorted by morphological features of canopy structure, differ between long- and short-shoots (175%), on the two genders of tree (131%), in the juvenile and reproductive portions of a canopy (183%), and with the presence or absence of seed on short-shoots in the reproductive portion of megasporangiate canopies (114%). Basipetal leaves of long-shoots and leaves of short-shoots have similar values of SLA.
  
  
  CONCLUSIONS
  With the exception of the acropetal decrease in SLA along long-shoots, the differences among the several classes of leaf seem to reflect local sink strength, even though the sink itself develops after leaves mature. The large overall range in the values of SLA in Ginkgo underscores the relevance of the details of canopy structure to parsing ecological phenomena.
authors.affiliation: Department of Plant Sciences, University of California, Davis, California 95616, USA. mxianson@pacbell.net
authors.forename: Michael L
authors.initials: ML
authors.lastname: Christianson
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Niklas
mesh_terms: D044822:Biodiversity; D002244:Carbon / Q000378:metabolism; D020441:Ginkgo biloba / Q000033:anatomy & histology*; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000254:growth & development; D018520:Plant Shoots / Q000033:anatomy & histology; D012621:Seasons
chemical_list: D002244:Carbon