If you have searched for the princess flower recently, you may have noticed two names: Tibouchina urvilleana and Pleroma urvilleanum. Both refer to the same garden plant. The difference comes from a major reclassification of a large group of melastomes.
Quick answer. Many plants long known as Tibouchina have been moved to the genus Pleroma and a few other genera. The princess flower is now listed by major botanical databases as Pleroma urvilleanum. Nurseries and gardeners still use the older name widely, so you will see both.
Why Tibouchina needed fixing
Tibouchina was historically a large, broadly defined genus of showy shrubs and herbs from tropical America, with well over two hundred species. Its members share the same general appearance: opposite leaves with strong longitudinal veins, and flowers with five petals and curved stamens, usually purple or pink.
Shared appearance does not always mean shared ancestry. When researchers compared DNA and detailed anatomy, they found that Tibouchina in the broad sense was not a single natural group. Some of its species were more closely related to other genera than to each other. Under the principle that genera should include a common ancestor and all of its descendants, the genus had to be divided.
What happened
A revision published around 2019 by a team of melastome specialists reorganised the group. In outline:
- Tibouchina in the strict sense was narrowed to a smaller set of species, based on the original type species.
- Pleroma was reinstated for a large group of mostly Brazilian and southern species, including the popular garden plants.
- Chaetogastra and other genera took other former Tibouchina species.
As a result, plants familiar from gardens changed names. Tibouchina urvilleana became Pleroma urvilleanum, and Tibouchina granulosa became Pleroma granulosum.
Why you still see the old name
Several reasons:
- Time lag. Books, nurseries, labels and websites take years to update.
- Familiarity. Gardeners know Tibouchina, and it remains the name people search for.
- Disagreement. Taxonomy is not static. Some authors adopt a change quickly and others wait to see whether it is widely accepted.
None of these means anyone is wrong. It simply means a plant may carry two valid-looking names at once.
What name should you use?
- On a label or plant list: write both, for example, Pleroma urvilleanum (syn. Tibouchina urvilleana).
- Searching for plants: try both names.
- Scientific writing: follow the name accepted by a reference such as Plants of the World Online (see where to check accepted names).
On this site we keep covering the genus under its familiar name, for example in Tibouchina: The Princess Flower Genus and propagating Tibouchina from cuttings, while noting the newer classification.
Does the plant care change?
No. A name change does not alter the plant. Care for a princess flower is the same under either name. For landscape advice, see growing Tibouchina outdoors.
The bigger lesson
This case shows how plant classification is a work in progress. As methods improve, names are adjusted to reflect evolutionary relationships. The same thing has happened to many other groups, including Dissotis. For a broader grounding in how names work, read reading a botanical name.
Takeaways
- Tibouchina was split because it was not a natural group.
- Many garden plants now belong to Pleroma.
- Both names remain in everyday use, so search for both.
- The plant's needs have not changed.