Aloe jacksonii and A. elkerriana are narrow Ethiopian endemics and although they apparently comes from the same locality they are not closely related. Aloe elkerriana is a much larger growing and more vigorous plant than A. jacksonii with pendent or sprawling stems up to 5 m long

Walker, Colin C.

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Open Research OnlineThe Open University’s repository of research publicationsand other research outputsA tale of two Ethiopian aloes: Aloe jacksonii & A.elkerrianaJournal ItemHow to cite:Walker, Colin C. (2017). A tale of two Ethiopian aloes: Aloe jacksonii & A. elkerriana. Haworthiad, 31(2) pp. 31–32.For guidance on citations see FAQs.c© 2017 Haworthia Society and The AuthorVersion: Version of RecordCopyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyrightowners. For more information on Open Research Online’s data policy on reuse of materials please consult the policiespage.oro.open.ac.ukAloe jacksonii is a very attractive, dwarf-growing species. It has short, erect or procumbent stems up to 20cm long which branch freely from the base forming clumps (Fig. 1) that can be up to 50cm or more across. Its leaves are spotted, narrowly tapering with a rough spotted surface and short teeth on the margins (Fig. 2). is species was named in 1955 by G.W. Reynolds for Major T.H.E. Jackson, who discovered it at El Kerré in the Ogaden Province of Ethiopia in 1943 whilst stationed there during the Second World War. Major Jackson wrote that “El Kerré is a strange rock outcrop with precipitous sides, and the station was built below the precipice. ere is a steep path winding up a cle, and the aloes were found along the edge at the top” (Reynolds, 1955). However, when Maurizio Dioli revisited El Kerré in 2000, he was unable to locate A. jacksonii but instead found another species which he described in 2007 as Aloe elkerriana (Dioli & McCoy, 2007). ere are, therefore, mysteries surrounding these plants. Firstly, it is strange that Major Jackson did not nd A. elkerriana back in 1943 because it is apparently quite common at El Kerré (Carter et al., 2011). Secondly, the origin of A. jacksonii is now uncertain: did it ever grow at El Kerré, has it died out from that location, or did Major Jackson incorrectly report its type locality? Whichever of these possibilities turns out to be correct, this species is currently only known from cultivated material derived from the original Jackson collection, hence there is only a single known clone in cultivation and all plants are presumably genetically identical.In my experience, A. jacksonii owers freely even as a small plant, making it highly desirable in cultivation where space is at a premium. Its inorescence is unbranched up to 30cm tall, bearing deep coral pink owers that are white-tipped at the mouth and up to 27mm long (Fig. 3). Aloe jacksonii is also of interest because of its chromosome count (cytology). Aloeis a very large genus with over 550 species, subspecies and varieties (Carter et al., 2011), A tale of two Ethiopian aloes:  Aloe jacksonii & A. elkerrianaColin C. Walker (c.walker702@btinternet.com) Fig. 1 Fig. 231the vast majority of which are diploid with chromosome counts of 2n = 14 (Rowley, 2017). Amongst a small minority of species there are relatively few (about 6%) that are polyploid with higher chromosome counts. Interestingly, Aloe jacksonii is one of these, being tetraploid with a count of 2n = 28 (Brandham, 1971); this might account for its robust growth in cultivation.e closest relative to A. jacksonii appears to be A. cremnophila from the Dhalo Escarpment, the highest point (2,400m) in Somalia (Carter et al., 2011). is species is also tetraploid and has a similar growth habit, but the leaves are unspotted (Brandham et al., 1994). One signicant dierence in my experience between A. cremnophila and A. jacksonii is that the former is an incredibly reluctant owerer, whereas the latter is very free-owering.As currently understood, both A. jacksoniiand A. elkerriana are narrow Ethiopian endemics and although they apparently come from the same locality they are not closely related. Aloe elkerriana is a much larger growing and more vigorous plant than A. jacksonii with pendent or sprawling stems up to 5m long. Its inorescence is also much larger up to 50cm tall and well branched. As yet I have no experience of growing A. elkerriana, so I would be very interested to hear from any Haworthiad reader who has a spare cutting!ese species have similar ecology because they are both cremnophytes: plants that grow solely on clis. Several other aloesgrow exclusively on clis and hence are referred to as obligate cremnophytes. Such 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. cremnophila(Somalia), A. hardyi, A. meyeri (South Africa); A. tororoana (Uganda) and A. pendens, A. yemenica (Yemen) (Carter et al., 2011). ReferencesBrandham, P.E. (1971) e chromosomes of the Liliaceae: II. Polyploidy and karyotype variation in the Aloineae. Kew Bull., 25: 381–399.Brandham, P.E., Carter, S. & Reynolds, T. (1994) A multidisciplinary study of relationships among the cremnophilous aloes of northeastern Africa. Kew Bull., 49: 415–428.Carter, S., Lavranos, J.J., Newton, L.E. & Walker, C.C. (2011). Aloes – e denitive guide. Kew Publishing, Royal Botanic Gardens, Kew/British Cactus & Succulent Society. Dioli, M. & McCoy, T. (2007). Aloe elkerriana(Asphodelaceae), a new Ethiopian species from the type locality of A. jacksonii. Haseltonia 13: 34–37.Reynolds, G.W. (1955) A new Aloe from Ethiopia. J. So. Afr. Bot., 21: 59-61, pl. X.Rowley, G.D. (2017) Succulents in cultivation – breeding new cultivars. British Cactus & Succulent Society, Hornchurch, Essex.Fig. 332

A tale of two Ethiopian aloes: <i>Aloe jacksonii</i> & <i>A. elkerriana</i>

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