Hoya Library Article
Hoya lacunosa and Hoya krohniana: what the evidence can tell us
Scott and Buot (2022) could not establish from their study that Hoya lacunosa and Hoya krohniana were distinctly different species. Their findings questioned the separation, but did not prove that the two are one species. Understanding that unresolved conclusion is essential when comparing the study with the names currently accepted by Kew.
Research status: This page summarizes documented evidence and its limits. It does not authenticate an individual plant or propose a taxonomic change.
Are they currently treated as separate species?
At the evidence check on 23 October 2026, Kew’s Plants of the World Online accepted both Hoya lacunosa Blume and Hoya krohniana Kloppenb. & Siar. Its records give first publication dates of 1827 and 2009, respectively. A database’s acceptance of a species does not verify the identification of a plant sold under that name.
What did the leaf study find?
Scott and Buot (2022) examined 30 fully expanded leaves from one cultivated plant under each name, plus an outgroup. The trade identifications were not independently verified. Thirty leaves from one plant are repeated observations of that plant, not 30 independent plants.
| Leaf character | Material labelled H. lacunosa | Material labelled H. krohniana |
|---|---|---|
| Length | 27.86–74.36 mm | 16.47–30.18 mm |
| Width | 9.59–20.58 mm | 13.68–20.50 mm |
| Outline | Narrowly elliptic to elliptic | Elliptic to ovate |
| Base shape | Cuneate or convex | Convex, cordate or rounded |
| Base angle | Acute to obtuse | Obtuse to reflex |
The groups overlapped in some characters. The authors found little separation in the vein patterns they could assess; finer veins were obscured or disturbed during preparation. Their comparison of pollinaria—the structures carrying pollen masses—was preliminary and used images from the original H. krohniana description.
What did the authors conclude?
The authors could not establish the two as distinctly different species from their results. They found differences in leaf shape and size, but considered these insufficient because leaf form can vary in Hoyas. The vein patterns they could examine showed little separation, while their preliminary comparison of pollen-bearing structures suggested strong similarities. They also acknowledged that their vein data alone were insufficient to establish how similar the plants really were.
They raised the possibility that H. krohniana could be a form of H. lacunosa or a geographically separated subspecies. These were possibilities for further investigation, not taxonomic changes established by the study. They recommended examining more plants, finer veins and flower structures, and comparing plants grown under uniform conditions. See their discussion and conclusion on pp. 2063–2064.
The study therefore left the relationship unresolved: it did not demonstrate a dependable species distinction, and it did not prove that the two names refer to one species. Its results also do not authenticate the Black, Silver, Splash or Super Silver labels attached to individual cultivated plants.
What should you keep with your plant?
- Keep the original received label, supplier and acquisition date, even if a later identification is proposed.
- Photograph several mature leaves with a scale, including the point where the leaf blade meets its stalk.
- Keep dated flower photographs and any measurements connected to the same plant.
- Record who supplied each cutting and its propagation history. Similar appearance alone cannot establish a shared clone.
Where the cultivated labels fit
The Library keeps received labels and their evidence visible without treating every label as an authenticated cultivar or clone. Explore the separate Black, Super Silver and Super Silver Black profiles for their documented descriptions and photographs.
Continue with the species accounts for Hoya lacunosa and Hoya krohniana. An identification question remains open when the evidence cannot connect a cultivated plant to an adequately documented reference.
Research and sources
- Scott, H. C. & Buot, I. E. Jr. (2022). Leaf architectural analysis of taxonomically ambiguous Hoya lacunosa Blume and Hoya krohniana Kloppenb. & Siar. Biodiversitas 23: 2055–2065. Methods p. 2058; Table 2 p. 2059; venation Table 3 p. 2060; discussion and conclusions pp. 2063–2064. Publisher and DOI.
- Royal Botanic Gardens, Kew. Plants of the World Online: Hoya lacunosa and Hoya krohniana. Acceptance and first-publication fields checked 23 October 2026.