With only two species in the region that isn't so difficult!
There's a set of photos of Heisteria perianthomega on Flickr, which could be correctly named.
https://www.flickr.com/photos/...
Herbarium specimens ..
http://www.europeana.eu/portal...
http://fm1.fieldmuseum.org/vrr...
It's an accepted name ..
http://www.theplantlist.org/tp...
Heisteria silvianii ..
http://www.theplantlist.org/tp...
There's several photos on the next link at the bottom ..
http://www.ufrgs.br/fitoecolog...
https://sites.google.com/site/...
http://tropical.theferns.info/...
An understorey plant in the forest, succeeding in moderate to quite dense shade[625]. Tolerant of dry to fairly wet soils[625].
Even when young the plant has a slow rate of growth
It could be either?! Heisteria silvianii looks to be better represented but that isn't conclusive.
