KIRCHOFF, BRUCE*, TAM LE, ALLYSON PREVETTE, SONJA CAUBLE, ELIZABETH SHELTON, and KIMBERLY HAMLET. Department of Biology, P.O. Box 26174, University of North Carolina at Greensboro, Greensboro, NC 27402-6174. - Early floral development in Musa velutina (Musaceae).
The genus Musa is monecious, with flowers arranged in hands.
Each hand develops in the axil of a primary bract, and consists of two
rows of flowers. The entire inflorescence is made up of a definite
number of female hands, a small number of transitional hands, and an
indefinite number of male hands. The flowers consist of three sepals,
three petals, two outer whorl stamen, two inner whorl stamen, and a
tri-locular, inferior ovary. The adaxial petal is not opposed by an
inner whorl stamen, resulting in only two stamen in this whorl. Flower
organogenesis begins with the flattening of the flower primordium, the
production of two bulges (the presumptive sepal primordia) in
adaxial-lateral positions, and the growth of the periphery of the apex
to produce the beginning of a floral cup. Growth of the periphery of
the primordium, which deepens the floral cup, is accompanied by the
differentiation of the adaxial side to produce three distinct
primordia, two sepal and one petal. At about this stage, or slightly
before, the abaxial sepal begins to be visible as a primordium that is
partially distinct from the lower rim of the floral cup. Continued
differentiation around the periphery of the flower begins the
formation of the outer stamen whorl on the adaxial side of the flower,
and produces two common petal/stamen primordia on the abaxial side.
Growth of the common primordia produces distinct abaxial petal and
inner stamen primordia. The adaxial petal continues to develop without
the production of an associated stamen, though the inner flank of this
primordium (the portion that forms a wall of the floral cup) does
develop a slight swelling. Growth of the floral cup, below the
insertion of the floral members, produces the cavity that forms the
gynoecial primordia.
Key words: banana, development, floral, flower, morphology, Musa, Musaceae