Marsdenia sp.
What are sold as “canoinha” in the potpourri trade appear to be follicles of a Marsdenia sp. Marsdenia spp. are vines. Follicles (in the native state) are 9-15 cm long x 3-4 cm wide, green to beige reddish and reticulated on the interior, dark brown finely reticulated on the exterior, and usually split for a few millimeters at both ends.
This Marsdenia sp. is probably native to Brazil.
Asclapiadaceae, also placed in Apocynaceae