An Excerpt from Jim Conrad's
Naturalist Newsletter

CISSUS GOSSYPIFOLIA

from the September 19, 2010 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, MÉXICO
TROPICAL GRAPES FLOWERING

Here we have several members of the Vine Family, the Vitaceae. One genus, with six species listed for this area, is Cissus. Nowadays a Cissus is flowering.

Its hand-sized, red flower clusters, or inflorescences, show up brightly against the forest's dark-green background. The woody vine bears simple (not compound), very variable-shaped leaves. A flowering branch is shown at the top of this page.

An interesting close-up of some flowers that already have lost their four petals and four stamens, leaving only developing ovaries submersed beneath shiny droplets of nectar, with slender, stigma-bearing styles poking up through the nectar, is shown below:

CISSUS GOSSYPIIFOLIA, flowers
*In 2016 more information on the Yucatan's plants is available on the Internet and it's more apparent now that this really is Cissus gossypifolia.
From very scant information and limited images on the Internet, I'm guessing that this is CISSUS GOSSYPIIFOLIA,* sometimes named C. formosa.