[Taxacom] Taxonomy and phylogeny of the cultivated Aloe

Finn N. Rasmussen finnr at bi.ku.dk
Mon Nov 26 09:34:44 CST 2007

Hello Taxacom'ers:
Species of Aloe are cultivated and used in cosmetics and medicine in
many parts of the world. It seems that the biggest plantations now a
days are found in the US and China. I was recently contacted by a Danish
resident of Morocco who is contemplating starting an Aloe plantation
there. Aloe plants are available from local nurseries and also
frequently found naturalized. The future Aloe-planter asked me how one
could be sure that the local plants are "right ones", considering that
more than 350 spp. are described in the genus.

Well, the right one must be Aloe vera (L.) Burm. f., which is often
referred to as A. barbadensis Mill., or in technical documents as "A.
Vera Barbadense Miller" or similarly confused designations.  I was
surprised to find out how little facts are available on the taxonomy and
nomenclature of this species. The last treatment seems to be in Reynolds
"Aloes of tropical Africa" (1966). Does any of you know:

(1) Aloe vera was described by Linnaeus as A. perfoliata var. vera. Who
found out that N. Burman's elevation of this entity to the rank of
species seems to beat Miller's A. barbadense with a few days? Both were
published in 1768. When and where was this finding published - it must
be later than Reynold's monograph from 1966. 

(2) Types: has lectotypes been designated for any of the two names?

(3) The specimen of A. perfoliata L. in LINN seems to be officially
unidentifiable, but shouldn't it be possible to match it with some
current species using modern techniques? If the specimen is what is now
called A. ferox, shouldn't perfoliata then be used for that entity? On
the other hand, this might not really be worth the effort :-)

(4) Are A. vera L. and A. barbadense really the same species? Could A.
barbadense belong to a different infraspecific taxon? 

(5) Does a survey of subspecies and varieties of A. vera exist? I have
seen many varietal names floating around, and it seems likely that there
are several strains and cultivars which are not equally suitable for
different purposes. What is it really that is cultivated in the big
plantations? Do Aloe-farmers care about infraspecific taxa or cultivars?

(6)  Which species may be encountered as naturalized in North African
countries like Morocco? The natural range of the genus seems to end in
Ethiopia and Socotra. 

(7) It seems generally agreed that Aloe vera is never found in the wild
(it is the only Aloe species not CITES-appendicized!). It is therefore
usually not included in floras, not even in comprehensive ones like
Flora of Egypt or Flora of Ethiopia. Are modern (newer than Reynolds
1950 and 1966) detailed descriptions of A. vera and other economically
important Aloes available anywhere?     

(8) Is anybody working on the phylogeny of the genus? Which are the
closest relatives of A. vera?

A private organization (or company, really) in Texas called IASC
<http://www.iasc.org/%20>  (The International Aloe Science Council,
Inc.) issues certificates concerning chemical contents of Aloe-products,
but does apparently not deal with botanical veracity. 
Cheers,  Finn N. Rasmussen, Copenhagen

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