Like yesterday’s Jacaranda decurrens, Aristolochia ridicula is native to Brazil. This evergreen climbing vine has some of the most peculiar flowers, truly resembling nothing I’ve ever seen before! Today’s photographer, Bruce Brethauer@Flickr, describes this as “probably the most unusual flower that I have ever photographed” (he also suggests browsing through these additional photographs of Aristolochia ridicula).
The flower in today’s photograph is perhaps better understood if you view this cross-section of Aristolochia fimbriata. You’ll note that the pollen-bearing and pollen-receiving reproductive parts are buried deep within the tube-like (pipe-like?) perianth; these are not visible in today’s photograph. Rather, we are seeing a face-on view of the end of the 6 cm (~2.5 in.) long perianth tube, with the white hairs borne at the entrance to the tube. In this instance, the perianth also has two triangular lobes which are highly-ornamented and covered with appendages. Presumably, the combination of colours, appendages, and hairs have some purpose in attracting or trapping pollinators, but I am unable to find a reference for this particular species.
It seems like this exotic vine is rare in horticulture, with very few retailers. It is, however, well suited to be grown in warm temperate climates as a container plant, surviving as long as temperatures do not go below freezing and growing damage-free as long as temperatures are above 15 Celsius (60F). Aristolochia ridicula grows best in light shade, and with an available structure for support, it can reach 3m (10 ft.) in height. Both the cordate-reniform leaves (heart- to kidney-shaped) and stem are coated in a furry-like set of hairs. In Brazil, these vines grow along roadsides, usually on fences at forest or savannah borders.
The Aristolochiaceae, or birthwort family, contains seven genera by some accounts (more in others, depending on how one treats Asarum). Aristolochia has the largest number of species by far within the family, with around 400-500 species. Most species of Aristolochia are commonly known as birthworts, pipevines or Dutchman’s pipes.