Sweetpotato
cultivars vary in their ability to flower. Under normal conditions in
the field, some cultivars do not flower, others produce very few flowers and
others flower profusely.
The inflorescence is generally a cyme in
which the peduncle is divided into two axillary peduncles; each one is further
divided in two after the flower is produced (biparous cyme). In general,
buds of first, second and third order are developed. The flower buds are
joined to the peduncle through a very
short stalk called pedicel. The
colour of the flower bud, pedicel and peduncle varies from green to
completely purple pigmented.
The flower is bisexual. Besides the calyx and corolla, they contain the
stamens that are the male organs or androecium
and the pistil that is the female organ or gynoecium.
The calyx consists of 5 sepals, 2 outer and 3 inner, that stay attached to
the floral axle after the petals dry up and fall.
The corolla consists of 5 petals that are fused forming a funnel, generally
with lilac or purple limb with reddish to purple throat (the inside of the
tube). Some cultivars produce white flowers.
The androecium consists of 5 stamens with filaments that are covered with
glandular hairs and that are partly fused to the corolla. The length of
the filaments is variable in relation to the position of the stigma. The anthers
are whitish, yellow or pink with longitudinal dehiscence. The pollen grains are
spherical with the the surface covered with very small glandular hairs.
The gynoecium
consists of a pistil with a superior ovary, two carpels, and two locules that
contain one or two ovules. The style is relatively short and ends in a
broad stigma that is divided into two lobes that are covered with glandular
hairs. At the base of the ovary, there are basal yellow glands that
contain insect-attracting nectar. The stigma is receptive early in the
morning and the pollination is mainly done by bees.
