Revision of Passiflora Subgenus Decaloba ... - Passion Flowers

142
pigmentation in the young stems and abaxial surfaces of the sepals (Storey,
1950). I was unable to locate his vouchers and because P. suberosa ssp.
suberosa and P. suberosa ssp. litoralis both occur in the Hawaiian Islands, I
cannot be certain which subspecies he sampled. Snow and MacDougal (1993)
also found that P. pallida from Jamaica was a polyploid (tetraploid) with a
chromosome number of 2n=24. With regard to breeding systems, Passiflora
pallida and P. suberosa ssp. suberosa are often self-compatible and autogamous
in cultivation. MacDougal also found that a clone of P. suberosa ssp. litoralis
from México was not self-compatible, but a different clone from New Caledonia
did prove to be self-compatible.
As shown in the phenetic analyses of P. suberosa s.l., there is clearly some
overlap in the morphological characters of P. pallida and P. suberosa. This may
indicate that there is limited gene flow occurring between these species, and the
molecular data are consistent with this hypothesis. However, most specimens of
P. suberosa and P. pallida are clearly separable and the inclusion of P. pallida, a
well-supported cladospecies, within the circumscription of P. suberosa would
render this species extremely non-monophyletic and obscure the distinctiveness
of an early divergent lineage within the supersection. According to the molecular
data there definitely seems to be gene flow between the subspecies of P.
suberosa, and though they are morphologically distinct, I felt it best to treat these
two somewhat geographically isolated taxa at the subspecific level (as opposed
to the species level). The exact impact that hybridization and polyploidy are
having on the evolution of P. pallida and P. suberosa remains unknown, but it is