Revision of Passiflora Subgenus Decaloba ... - Passion Flowers

Notes
348
Passiflora juliana is most closely related to P. viridiflora and aside from floral
adaptations in P. viridiflora resulting from a shift in pollinators, these two species
with greenish yellow flowers borne in conspicuous, indeterminate, terminal
inflorescences are very similar. Both species possess large, peltate, trilobed
leaves that have a central lobe that is distinctly narrowed at the base. They both
may possess stems that have some red pigmentation, but those of P. viridiflora
are generally bright red, while those of P. juliana are commonly reddish purple.
Passiflora juliana can also be separated from P. viridiflora vegetatively because
that species has small, narrowly ovate stipules, as opposed to the larger, ovate,
foliose stipules of P. juliana. Passiflora juliana bears the shallow cup-shaped
flowers typical of most of the members of the supersection and subgenus,
whereas P. viridiflora possesses long, tubular flowers with a greatly elongated
androgynophore. Passiflora juliana is a very distinctive taxon possessing the
shortest floral stipe in supersection Cieca, a limen floor that is distinctly purple
and an androgynophore flushed with purple at the base to just above the middle.
Controlled self-pollinations performed by MacDougal (1992) produced no fruits
in P. juliana, indicating that the species is self-incompatible. In addition, he found
that no fruits were produced by autogamy during ten years of cultivation. I also
found this to be true in my one clone of P. juliana (MacDougal 492GR) grown in
greenhouses at the University of Florida.
The light green flowers are likely adapted to a small or medium-sized insect
pollinator, but J. M. MacDougal (1992) observed a hummingbird visiting the