Data from: Inflorescence and flower development in Musa velutina H. Wendl. & Drude (Musaceae), with a consideration of developmental variability, restricted phyllotactic direction, and hand initiation

Premise of research. Inflorescence and flower structure in the Musaceae is
unique in the Zingiberales. The inflorescence lacks the obvious cincinnus
structure that characterizes the order, and the flowers are unisexual.
Previous studies were conducted using cultivated varieties and were
carried out with sectioned material, which does not permit accurate
developmental descriptions. Developmental study of a wild species with
modern methods addresses these shortcomings and provides more accurate
descriptions. Methodology. Young inflorescences and flowers were collected
from botanical gardens in Hawaii and Australia and critical-point dried
for observation with a scanning electron microscope. Pivotal results. All
shoots and inflorescences have sinistrorse (left-handed) phyllotaxy, and
the sequence of flower initiation is usually correlated with this pattern.
Initiation begins on the cathodic side of the hand (opposite the direction
of phyllotactic rise) and progresses anodically (in the direction of
phyllotactic rise). Within this general pattern, the sequence of flower
initiation is variable, even within the same inflorescence. Five patterns
of initiation are reported, with additional variation within each pattern.
Both male and female flowers have similar early developmental patterns but
diverge at the time of petal/inner androecial formation. In male flowers
the anterior side of the flower develops slightly ahead of the posterior,
while in female flowers the posterior side develops slightly ahead of the
anterior. While consistently present in the material analyzed here, these
differences are not apparent at the time of gynoecial initiation or in the
mature flowers. Conclusions. The banana inflorescence is another example
of how higher-level phyllotactic patterns can influence the sequence of
organ initiation at lower levels. Despite variability in the sequence of
flower initiation in a hand, the best interpretation of the hand remains a
cincinnus. Variability in inflorescence and floral development is rarely
reported and may be more common than currently supposed.