Carlos here is some information I was able to get for you. I hope this helps. Thanks to Ron for helping me for ID assistance- Copied from his email.
"Here is my assessment as of this point:
My impression is that the plant is either :
The flower color is more consistent with M.macrocalyx , although the leaves have more lobes than what is apparently very typical for M.macrocalyx.
The seeds seem to be larger than is typical for M.macrocalyx and additionally seem to be lacking any hairs.
The leaves and seeds are more typical for Merremia dissecta although the corolla seems to be smaller and the reddish coloring in the tube which is most commonly seen in M.dissecta is absent.
There are some strains of Merremia dissecta which have little to no coloring in the tube but these strains are rarely seen.
I'm tending towards Merremia macrocalyx as the ID of 1st choice and Merremia dissecta as the ID of 2nd choice but it is certainly possible that it may be a different Merremia other than the 2 species I have cited.
I would welcome any input from anyone at any point who could provide more accurate ID details regarding the plant in question.
My thoughts are that if the plant is grown out and photo-documented (at all growth stages) regarding particular details , utilizing macro-photography that some additional details may be garnered to assist in clarifying the iD."
This is a rare variety. See this very interested commentary in Economic Botany Nr 61 Vol 2:
The only record found of the roots being eaten
was recently published by Arenas (2003). Only
M. dissecta var. edentata (Meisner) O’Donell is
native in the Gran Chaco, Argentina, where Arenas
worked with the Toba and Wichí people (Fig.
2), although there are scattered locations where
M. dissecta var. dissecta has been introduced.
The second variety is restricted to South America
and has not been dispersed outside that region
(Fig. 2). Those plants were first discovered in
Brazil, grown in the botanical garden in Bonn
(horto botanico Bonoiensi), and called Ipomoea
fulva by Giuseppe Bertolini in 1838. Then
George Gardner found them in Rio de Janeiro
and called them I. nigricans in 1842. Meisner,
studying the family for Martius’s Flora Brasiliensis,
did not think that the climbers should be given
specific rank and called them I. dissecta var. edentata
in 1869. Meisner (1869) was obviously confused
by this problem, because he also named
them I. maximiliani in spite of their having two
previous epithets at species rank. It was not until
O’Donell (1941) examined the genus that the variety
was moved to M. dissecta var. edentata.While there are clear similarities between these
two variations, corollas are completely white in
M. dissecta var. edentata but white with a reddishpurplish
center in M. dissecta var. dissecta. Moreover,
the sepals average longer (20–35 mm.) in
var. edentata than in var. dissecta (18–25 mm.).
Leaf lobes in var. dissecta are toothed while those
in var. edentata are mostly entire.
Arenas (2003) found only some of the Tobas
using the plants, and although the Wichí formerly
used them assiduously, only those in more remote
villages still do. Roots are cut up if large, but left intact
if small. The roots are put in a pot and boiled,
or sometimes they are baked in ashes. Cooked roots
are eaten with abundant oil as a dressing. Arenas
thought that they tasted a little like the batata (Ipomoea
batatas), although they tended to be insipid.
Formerly they were taken entirely from wild places,
but a few individuals now cultivate them in their
home gardens. This is an important food only during
the winter drought period.