Pk. Diggle, ONTOGENIC CONTINGENCY AND FLORAL MORPHOLOGY - THE EFFECTS OF ARCHITECTURE AND RESOURCE LIMITATION, International journal of plant sciences, 158(6), 1997, pp. 99-107
Floral form and function commonly vary quantitatively and qualitativel
y within inflorescences. Overall floral size, the sizes of individual
floral organs, and the frequency of successful fruit and/or seed matur
ation may decline distally within inflorescences. These frequently obs
erved patterns of variation have been attributed to competition for li
mited resources among developing flowers and fruits. The variation, ho
wever, can also be due to architecture, that is, to sources of variati
on inherent in plant axes. Floral morphology may change with position
on an inflorescence axis, even in the absence of resource competition.
Experimental analyses of Solanum hirtum and Arabidopsis thaliana iden
tify the separate effects of architectural and resource limitation on
floral development and morphology. The effects of architecture may mim
ic, mask, or lead to misinterpretation of the effects of resource comp
etition on floral form. Floral morphology and function may be characte
rized as ontogenetically contingent: the morphology and fate of a deve
loping flower depend on the events that have preceded it during the on
togeny of the organism and on where it occurs within the architecture
of the individual. Careful consideration of the role of ontogenetic co
ntingency in diverse taxa will be required to fully understand pattern
s of variation in floral morphology and function within individuals an
d may ultimately enhance our understanding of morphological diversific
ation among taxa.