Contents
of the Summer 2014 Northants News
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Aloe
cremnophila and
Aloe
jacksonii
–
cliff-dwellers from the Horn of Africa
Colin
C. Walker
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My
plant of Aloe
cremnophila is flowering for me for the first time, and such an
exciting event makes it worthy of a report for Northants
News.
The
plant was obtained as a single stem back in 2009 from Brian McDonough of
the Glasgow branch. As you can see from the photo it has grown well, and
in the 4½ years in my care has produced a clump of 20 branches that is
currently accommodated in a 25 cm diameter pot that I grow as a hanging
pot. The branches could be described as being procumbent rather than
pendulous, although the oldest and longest stem does hang down. Its leaves
are up to 13 cm long, are uniformly grey-green in colour without spots,
but with small sharp teeth up to 2 mm long on the leaf margins.
So I
would describe my plant as being reasonably large, and is now flowering
for the first time, but it has only produced a single spike. This is
erect, unbranched, just over 30 cm tall, with flowers about 26 mm long,
pink but yellow-green at the mouth.
Reynolds
(1961) said that “Of several plants cultivated in my garden at
Bryanston, Johannesburg, only one stem produced an inflorescence”.
Similarly my plant has been a reluctant flowerer, and Brian’s has yet to
flower. From this I think it’s safe to conclude that this species is a
rather shy flowerer indeed.
My plant is a propagation of ISI
1450, which in turn was propagated from the type collection
Reynolds
8450B
which was used to describe the species. The plant was first collected by
Peter Bally in October 1956 on cliff faces of Daloh Escarpment at 6,500
feet (1,970 m), about 13 miles N. of Erigavo, Somalia, and it is currently
known from no other location, so the species could be described as a
narrow endemic with a very restricted distribution.
Left: Flower spike of Aloe
cremnophila, c. 30 cm tall.
Click here
for a better image
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The closest relative to this species appears to
be A.
jacksonii from the Ogaden in Ethiopia, which has similar
short, erect or procumbent stems which branch from the base to form clumps,
whilst the leaves are similar in shape with a rough surface, but are spotted.
A. jacksonii was
named for Major Jackson, who discovered it at El Kerre in Ethiopia in 1943
whilst stationed there during the Second World War. Major Jackson wrote that
“El Kerre is a strange rock outcrop with precipitous sides, and the station
was built below the precipice. There is a steep path winding up a cleft, and the
aloes were found along the edge at the top” (Reynolds, 1955). However, M.
Dioli revisited El Kerre in 2000, searched for A.
jacksonii but was unable to locate it, but instead found
another species which he later described as A.
elkerriana (Carter
et
al., 2011). There are, therefore, mysteries surrounding these plants.
Firstly, it is strange that Jackson didn’t find
A. elkerriana
back in 1943, because it is apparently quite common at El Kerre. Secondly, the
origin of A.
jacksonii is now uncertain: did it ever grow at El Kerre,
has it died out from that location, or did Jackson incorrectly report its type
locality? Whichever of these possibilities turns out to be correct, currently
this species is only known from cultivated material from the original
collection.
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Far
Left:
Aloe
cremnophila
in a 25 cm diameter pot.
Left:
Aloe
jacksonii
in an 8 cm square pot.
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A.
cremnophila was so named because it only grows on cliffs,
i.e. it is cliff-loving or a cremnophyte, a plant that grows on cliffs. However
it is not unique as an Aloe that only grows on cliffs, i.e. is an obligate
cremnophyte. A.
jacksonii and A.
elkerriana
have already been discussed. Other species include: A.
inamara, A. mendesii (Angola);
A.
ankoberensis, A. downsiana, A. pulcherrima (Ethiopia);
A.
amicorum, A. doddsiorum, A. tartarensis (Kenya);
A. corallina, A. huntleyana, A. omavandae, A. pavelkae (Namibia);
A.
collenetteae (Oman);
A.
squarrosa (Socotra); A.
hardyi, A. meyeri (South
Africa); A.
tororoana (Uganda) and A.
pendens, A. yemenica (Yemen) (Carter et
al., 2011). Further afield and in other groups of succulents,
cliff-dwellers are also known. In Mexican Crassulaceae, for example, the two
species of the genus Cremnophila were separated from Echeveria and Sedum
partly because of their cliff-dwelling habit, and most species of the more
familiar genus Pachyphytum also grow hanging down from precipitous cliffs.
In southern Africa a wide range of species has been discovered on cliffs. These
plants were the subject of Ernst van Jaarsveld’s PhD. thesis and rumour has it
that these will become the basis of a forthcoming book from this prodigious
author, so we eagerly await further revelations on cliff-dwelling succulents in,
hopefully, the not too distant future.
References
Carter, S., Lavranos, J.J., Newton, L.E. &
Walker, C.C. (2011).
Aloes - The definitive guide.
Kew Publishing, Royal Botanic Gardens, Kew / British Cactus & Succulent
Society.
Reynolds, G.W. (1955) A new Aloe from Ethiopia. J.
So. Afr. Bot., 21: 59-61, pl. X.
Reynolds, G.W. (1961) A new Aloe from Somali Republic. J.
So. Afr. Bot., 27: 77-79, pls. XIII & XIV.
Colin
[colin.walker(at)open.ac.uk]
