''Aloe juvenna'' (tiger-tooth aloe) is a species of

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

in the genus ''

Aloe ''Aloe'' (; also written ''Aloë'') is a genus containing over 650 species of flowering plant, flowering succulent plant, succulent plants.WFO (2022): Aloe L. Published on the Internet;http://www.worldfloraonline.org/taxon/wfo-4000001341. Acc ...

''. It is popular in cultivation but extremely rare in its natural habitat in

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

Distribution and habitat

It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

in East Africa. Here it is restricted to a small rocky area in the mountainous south west of the country, near the border with Tanzania.

Discovery and history in cultivation

It has long been common in cultivation, but its origin was not known. The first recorded cultivated specimens were in South Africa, but although there were rumours that it had come from Kenya, its origins were a mystery even then. It was first believed to be a juvenile Aloe, due to its small size, and it was labelled "juvenna" ("juvenile") for this reason. However that label eventually became its formal name. Later, it was thought to be a hybrid perhaps of '' Aloe distans'' with ''

Haworthia coarctata ''Haworthiopsis coarctata'', formerly ''Haworthia coarctata'', is a species of flowering succulent plant from the Eastern Cape Province, South Africa and naturalized in Mexico. It is one of the species of ''Haworthiopsis'' that is commonly cultiv ...

'' or a species of ''

Astroloba ''Astroloba'' is a genus of flowering plants in the family (biology), family Asphodelaceae, subfamily Asphodeloideae,Stevens, P.F. (2001 onwards)"Asphodeloideae" ''Angiosperm Phylogeny Website'', retrieved 2016-06-10 native to the Cape Province ...

''. It underwent

genetic testing Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...

in the 1970s and, when it was discovered that ''Aloe juvenna'' had a doubled set of chromosomes (tetraploidy), it came to seem more likely that this Aloe came from

East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

, where most other tetraploid Aloes originate. The name ''Aloe juvenna'' was finally published as a valid species name in 1979. Finally, in 1982, an expedition in the far south west of Kenya discovered a few plants on a tiny rocky mountainous ridge, high about tropical rainforest. The existence of these plants in such a remote locality confirmed that the species was a natural one. However, how it originally came to be brought into cultivation in the first place, remains a mystery.

Identification

''Aloe juvenna'' is frequently confused with ''

Aloe squarrosa ''Aloe squarrosa'' is a species of flowering plant in the Asphodelaceae family. It is from the island of Socotra, Yemen. Description ''Aloe squarrosa'' has smooth, green, spotted leaves that curve backwards. These recurved leaves are kept only ...

'' from the island of Socotra. However ''Aloe squarrosa'' has long, smooth, spotted leaves that curve backwards. These recurved leaves are kept only around the head or top of each stem, with dead leaves falling off the lower parts of the stem. It is relatively rare in cultivation. ''Aloe juvenna'' has many short, straight, compact triangular leaves, which are densely packed all along the stems. It is common in cultivation but extremely rare in habitat. ''Aloe juvenna'' is also a tetraploid, with a double set of chromosomes (28, instead of 14) and, in appearance, does not resemble any other Aloe species from the region.

References

{{DEFAULTSORT:Aloe juvenna juvenna Endemic flora of Kenya Plants described in 1979