DOUST, ANDREW, N.L. Department of Botany, University of Missouri-St Louis, St Louis, MO 63121. - Floral morphology and development in Winteraceae.
The flowers of Winteraceae show great diversity in number and
arrangement of organs. In most genera of Winteraceae a continuity of
initiation from sepals through petals, stamens, and carpels results in
relatively few floral arrangements, these being variations on
decussate and whorled patterns. However, a diversity of phyllotactic
patterns is found in the flowers of Drimys winteri, resulting
from the unconstrained placement of petal primordia following a delay
between sepal and petal initiation. In all taxa there is
within-pattern variation in divergence angle and plastochrone ratio
correlated with the eccentricity of the floral meristem. Differences
in floral form define the genera of the Winteraceae and these
differences are controlled by the timing and duration of primordial
initiation, the position of initiation of the primordia, the shape of
the floral meristem, and the relationship between size of meristem and
size of primordium. An understanding of these ontogenetic processes is
important in understanding diversity and evolution of floral form in
Winteraceae.
Key words: floral development, phyllotaxis, Winteraceae