How many varieties of tradescantia are there?

Skip to: Defining the question // Counting species // Counting cultivars

People who become interested in tradescantias often start to wonder how many different types there are in total. It seems like a simple question, but the answer is frustratingly complex. In fact there are several different answers, depending on exactly what is meant by the question.

This article starts by explaining why the question is more complicated than it seems. I’ll then give the most useful answers about the number of species, and the number of cultivars.

Defining the question

The question is difficult to answer simply because there are lots of different possible interpretations, and no easy way to know which one a person intends.

The word “variety” is used to mean different things in different contexts. To answer how many varieties there are, we need to decide which meaning to use. Do we take the strict botanical sense, referring to a sub-population within a species? Do we take it in the horticultural sense, as a synonym for cultivar? Do we take it in a more general sense to include species and any divisions inside them?

The word tradescantia is also more ambiguous than it might seem. Tradescantia is a genus defined by botanists. But among growers and sellers, almost any plant within the Commelinaceae family is sometimes labelled as a tradescantia. And for specialist collectors, they may only be interested in one part of the genus, and ignore either the tropical or hardy side which isn’t relevant for them.

Finally, the question can also have different answers in different times and places. Species definitions are constantly evolving with new research, as classifications get combined, separated, or discovered – so there is never a “final count” of species in any group. New cultivars are produced all time, and old cultivars can become lost in cultivation and effectively extinct. Some plants may be commonly cultivated in one continent, and rare or absent in another.

All of this means that there’s no simple way to answer “how many varieties of tradescantia are there?”, without first asking a lot of follow-up questions to figure out what a person really wants to know! Since I can’t actually do that for everyone who googles this question, the rest of the article will lay out some of the numbers that might be relevant. That way anyone can combine the different figures they’re interested in for their own purposes.

Counting species

If you’re interested in how many types of tradescantia exist in the wild, you probably want to know about species. A species is defined by botanists observing plants that have evolved in their natural environment. Different species usually grow in different habitats and native ranges, and don’t tend to interbreed with each other much in the wild.

The best source for taxonomy information like this is Plants of the World Online, a database maintained by the Royal Botanic Gardens, Kew. The species counts I’ve given are based on Kew’s records at the time of writing, but the exact numbers change all the time as research develops.

Of these species, only a tiny handful are common in culivation. Most of them can only be found in the wild in their native range. But among the species which are common in cultivation, there are often many distinct clones in circulation which growers distinguish from each other. Which brings us on to…

Counting cultivars

If you’re interested in collecting different plants to cultivate, you probably want to know about cultivars. A cultivar is defined by growers as a unique form of a plant. There are often many different cultivars within the same species or hybrid, which can have different characteristics like flower colour or leaf shape. Cultivars of the same species would all be treated by botanists as the same plant, but for gardeners the subtle differences between them can be very significant.

This information comes directly from the cultivar checklist I maintain as International Cultivar Registration Authority (ICRA). Much like the species counts, these numbers are accurate as I write but will change over time.

Although those counts rule out cultivars which are definitely lost from cultivation, that doesn’t necessarily mean that every cultivar is available everywhere – many new or rare cultivars can only be found in certain parts of the world. There are also probably unnamed clones in circulation, which are interesting to growers but not on the checklist because they aren’t named cultivars.

These counts also don’t include cultivars from the rest of the family, even though they are often labelled as tradescantias for sale. If you’re an enthusiast you might be familiar with Tradescantia Tahitian Bridal Veil, Tradescantia Hijau Baru, or Tradescantia Rosato. But the truth is, none of those are Tradescantia cultivars at all! Instead they belong to other genera in the Commelinaceae family.

This is this big unanswered question so far. I am (currently!) only ICRA for the Tradescantia genus. There is not – and has never been – an ICRA for the rest of the family. So no-one has ever made a complete checklist of all known cultivars in the family, or counted them.

Based on my experience, I think there are probably far fewer cultivars in the rest of the family than in the Tradescantia genus alone. But when I dug into research for the ICRA checklist, I ended up finding more tradescantias than I expected – so the same may apply for other Commelinaceae. The upper boundary for my estimate is based on the possibility that there are the same number of cultivars in the rest of the family as in the Tradescantia genus. It’s a very rough guess though. I hope that one day I’ll be able to answer this question more precisely!

Conclusions

How many different varieties of tradescantia are there? It depends! On what you mean by tradescantia, and on what you mean by variety.

If you’re interested in wild plants, you probably want to know about species studied by botanists. The species in the Tradescantia genus and the whole Commelinaceae family are changing all the time in line with new research. But the current species counts can be checked fairly easily by referring to a botanical authority like Plants of the World Online run by Kew.

If you’re interested in growing and collecting plants yourself, cultivars are probably more relevant for you. I maintain the official checklist of Tradescantia cultivars, which you can always use to find out how many accepted cultivars exist today. There is currently no official checklist for cultivars in the rest of the Commelinaceae family, so there is no reliable way to count them.

If you came to this article asking how many tradescantia varieties there are, I hope your curiosity has been satisfied, even if you didn’t realise how complicated the question was to begin with!