TITLE:
Male Cone Evolution in Conifers: Not All That Simple
AUTHORS:
Christian Schulz, Kristina Vanessa Klaus, Patrick Knopf, Marcus Mundry, Veit Dörken, Thomas Stützel
KEYWORDS:
Pollen Cone, Phylogeny, Gymnosperms, Compound Cone, Microsporophyll
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.18,
August
29,
2014
ABSTRACT:
Despite the simple structure of male conifer cones, there is an enormous
variability in cone properties observed upon more careful examination. The
diversity ranges from simple cones to compound cones. Moreover, cones can be
distinguished according to different spatial distributions on the tree. Simple
cones are distributed either as solitary cones or as fascicular or clustered
aggregations, while compound cones only exhibit fascicular or clustered
aggregations. Here, we demonstrate that these different spatial distribution
patterns correlate with distinct leaf types and variable branching frequencies.
Furthermore, we provide new insights into the evolution of the sporangiophore,
particularly in Taxaceae. Two notably important and fast-evolving characters of
conifers are the number of sporangia per sporangiophore and the number of
sporangiophores per cone. We demonstrate, across many species and types of
cones, how these characters are able to adjust according to the optimal amount
of pollen.