Hoya benchaii is very similar to Hoya kloppenburgii, but here are a few differences (Thanks to Mary Carroll for unearthing all of this information!)
- Hoya benchaii can be differentiated from Hoya kloppenburgii in having ovate leaves as compared to lanceolate leaves.
- Hoya kloppenburgii also has a positively geotropic inflorescence with a long peduncle and an umbel of flowers that is flat to slightly concave; however, there are many more flowers per umbel, up to 15–20, as against 4–11 in Hoya benchaii.
- The basal part of the corolla in Hoya kloppenburgii is cream to pale yellow with white pubescent hairs, but pink and glabrous under the corona in Hoya benchaii. The bi-carpellate ovary in Hoya kloppenburgii is much more pointed, and longer, 2 mm compared to 1.6–1.8 mm in Hoya benchaii, based on the type description.
Above Hoya benchaii on the left and Hoya kloppenburgii on the right. I can’t believe that I was lucky enough to have both of these flowering at the same time!