Aloe pulcherrima is a large-growing, cliff-dwelling species from high altitudes in Ethiopia with a unique stem branching pattern. It is described both in cultivation and in habitat

Walker, Colin C.

English

Open Research Online (OU)

Open Research OnlineThe Open University’s repository of research publicationsand other research outputsAloe pulcherrima - a beautiful Ethiopian endemicJournal ItemHow to cite:Walker, Colin C. (2017). Aloe pulcherrima - a beautiful Ethiopian endemic. CactusWorld, 35(2) pp. 131–135.For guidance on citations see FAQs.c© 2017 BCSS, authors and illustrators of individual articlesVersion: 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.uk131CactusWorld Vol. 35 (2)Introducing Ethiopian aloesAloe is a very large genus; even with the excision of some species into the segregate genera Aloiampelos,Aloidendron, Aristaloe, Gonialoe and Kumara, thegenus still has around 500 species and about 60subspecies and varieties (Carter et al, 2011).  The genusis widespread throughout Africa, Arabia and theIndian Ocean islands, notably Madagascar.Ethiopia and Eritrea formed one country until 1991, but the two now independent countries are usuallytreated as a single entity in terms of their flora (Edwards et al, 1997).  Ethiopia is now a land-lockednation, since the northern coastal region becameindependent Eritrea.  Here these countries are treatedas a single phytogeographical unit in terms of the aloesthat occur there. The aloes of Ethiopia and Eritrea are moderatelydiverse.  Edwards et al (1997) recognised 38 species,including Aloe vituensis which has yet to be locatednorth of Ethiopia’s border with Kenya, so it is not, asyet, an Ethiopian Aloe.  The most recent completesurvey of aloes in Ethiopia and Eritrea (SebsebeDemissew & Nordal, 2010) recognised 46 species,again including A. vituensis.  Since that book waspublished (and even before), five additional specieshave been described from Ethiopia and Eritrea: Aloedjiboutiensis, downsiana, montis-nabro, neosteudneriand omoana.  Not counting A. vituensis, the currenttotal for Ethiopia and Eritrea is therefore 50 species,representing approximately 10% of the total for thegenus, so these countries together account for asubstantial number of Aloe taxa. Within this total, Aloe diversity is somewhat limitedcompared to other countries, since there are no reallybig tree aloes, no grass aloes and only a limited numberAloe pulcherrima – a beautifulEthiopian endemicColin C WalkerAloe pulcherrima is a large-growing, cliff-dwelling species from high altitudes in Ethiopia with aunique stem branching pattern.  It is described both in cultivation and in habitat.Photos by Janet Haresnape and the author.Fig. 2  A. pulcherrima showing the dichotomous branching ofthe stem at a younger age in an 18cm potFig. 1  A. pulcherrima in a 30cm-diameter pot, with the blue-greyfoliage contrasted attractively against the black glaze132 CactusWorld Vol. 35 (2)of spotted-leaved (maculate) aloes.  Most aloes fromEthiopia and Eritrea have large or even massive rosettesand some have very stout stems; many are pendulousor obligate cliff-dwellers (cremnophytes); none havesmall, stemless rosettes.  This is accounted for by thefact that Ethiopia in particular – Eritrea less so – has avery mountainous, varied topography, with much ofthe interior consisting of high plateaux bisected bydeep valleys and gorges (Edwards et al, 2010).  Only thenorthern coastline of Eritrea is low-lying with Aloeeumassawana being endemic and growing at sea level.Sebsebe Demissew et al (2001) tabulated the 40 aloesknown at that time and found that, in addition to A. eumassawana, only A. bertemariae and A. citrinagrow at low altitudes.  Consequently, the vast majorityof aloes from these countries, namely 37 of the 40species or 93%, are high altitude mountain-dwellers,growing at over 1,000m above sea level. Endemism within Ethiopian and Eritrean aloes ishigh – around 75% for the 50 species.  This compareswith 100% for Madagascar and around 60% forSouth Africa.  My figure differs from the 87%calculated by Sebsebe Demissew et al (2001) becausetheir figure was calculated on the basis of just 40species known at that time and does not take intoaccount the 10 species described since then, some ofwhich are non-endemic.Of the aloes endemic to Ethiopia one of the mostinteresting and attractive is Aloe pulcherrima Gilbert &Sebsebe featured here.  It was described only relativelyrecently (Gilbert & SebsebeDemissew, 1997), but it wasquickly brought intocultivation in the USA andEurope.  I have grown thisspecies successfully over along period and in 2015 mycolleague Janet Haresnapevisited and examined thisspecies in habitat in the centralhighlands of Ethiopia.Aloe pulcherrima incultivationI obtained my plant in April2004 and it has grown steadilysince then (Fig. 1).  The name‘pulcherrima’ means verybeautiful and the plant doesindeed live up to its name.  Fig. 3  A. pulcherrima in flower, showing the characteristic U-shaped peduncleFig. 4  Fruit of A. pulcherrima133CactusWorld Vol. 35 (2)The rosettes are large anddense.  The leaves are up to50cm long and 6cm wide atthe base, blue-green in colour,slightly glaucous, with fine butclearly distinct parallel lines(striae).  The leaf margin isprominently red when grownin full sun (not the case for myplant) and carries very small(0.2–0.3mm long) teeth, suchthat it could nearly bedescribed as being toothless.Aloes with entire, ie toothlessor nearly toothless, leafmargins are rare in Ethiopiaand Eritrea.  A particularlycharacteristic feature of theleaves is that they dry to a darkpurple colour, and indeed thefresh sap that exudes from acut leaf is also dark purple.  Inmy experience the plant is virtually impossible to keepin anything approaching show-worthy conditionbecause the leaf tips dry up remarkably easily and oldleaves rapidly dry up completely, making the plantappear somewhat untidy. A potentially unique feature of this Aloe is that thestems are not only long, up to 1m according to Gilbert& Sebsebe Demissew (1997), but they branchdichotomously as shown by my plant (Fig. 2), whichproduced the branching around six years ago.Dichotomous branching is a characteristic feature ofthe tree aloes now segregatedinto the genera Aloidendronand Kumara and for which aniconic species is namedAloidendron dichotomum(formerly Aloe dichotoma).  Iam unaware of other true aloesthat exhibit dichotomousbranching, although I suspectthat this feature may alsooccur in other high altitude,closely-related species.My single specimen has beenvery reluctant to flower,although it did oblige fouryears ago for the first time (Fig. 3).  The inflorescenceswere unremarkable for such alarge plant, being up to 43cmlong, unbranched but with a characteristic U-shape.Flowers were 4.0–4.3cm long with deep coral redtepals.In 2014 my plant not only flowered again but alsoproduced some fruits.  Since these have not beendescribed and illustrated before, I am providing thisnew information here.  The fruits were pale glaucousgreen in colour, obclavate (club-shaped, wider at thebase than at the tip), 2.4–3.2cm long and 0.7–1.0cmwide at the base (Fig. 4).  I did not harvest the seed soI cannot comment about its viability.Fig. 6  A. pulcherrima in habitat showing the thick stem (Photo: Janet Haresnape)Fig. 5  A. pulcherrima in habitat at the Asheton Maryam Monastery near Lalibela in northernEthiopia, June 2015 (Photo: Janet Haresnape)134 CactusWorld Vol. 35 (2)A final comment about my plant is that it wasbought from a Dutch nursery in 2004 labelled asAloe schelpei.  From growing this plant it is evidentto me that the identification is wrong.  The maindistinguishing features are that A. schelpei hasspotted, prominently-toothed leaves and orange-rednot coral-red flowers.  Most importantly of all, A. schelpei does not have the characteristicdichotomous branching pattern of the stems ofA. pulcherrima, but produces shoots at the base ofthe stem or randomly along the stem, so formingdense clumps (Reynolds, 1961; Reynolds, 1966; Glen& Hardy, 1986; Gilbert & Sebsebe Demissew, 1997).Aloe pulcherrima in habitatMy colleague Janet Haresnape visits African countries regularly, both for work and leisure, and Ihave asked her to photograph any aloes sheencounters.  In 2015 Janet revisited Ethiopia on ateaching project with The Open University and,during leisure time after completion of the work, shewas able to visit a number of aloes in habitat.  Mostexciting for me and unbeknown to her at the time, she encountered A. pulcherrima in its naturalenvironment.Janet visited the Asheton Maryam Monastery, whichlies at an altitude of almost 4,000m on Abuna Yoseph, the high mountain overlooking the town ofLalibela in north-central Ethiopia.  There sheencountered plants which I have since identified asA. pulcherrima (Figs. 5–9).Gilbert & Sebsebe Demissew(1997), when they firstdescribed this species,recorded it from severallocations in north-centralEthiopia at 2,480–2,750m,growing on “steep basaltslopes or cliffs with sparsecover of evergreen bushland”.However, as far as I can tellfrom the data available, Janet’slocality is a new record for thisspecies, and is almost certainlyan altitudinal record at nearly4,000m.  At the AshetonMaryam Monastery the plantsare indeed growing on cliffs(Figs. 5–8), so this species canbe described as cliff-dwellingor as a cremnophyte.  StemsFig. 7  A. pulcherrima in habitat with one exceptionally long pendent stem (Photo: Janet Haresnape)Fig. 8  A. pulcherrima in habitat growing in association with Aeoniumleucoblepharum (Photo: Janet Haresnape)were originally described asbeing thick, up to 8cm across,and at this site they are indeedthick (Fig. 6).  Stems were alsodescribed as being pendent orprostrate and up to 1m long,but one plant photographedby Janet has a stem that mightbe up to 2m in length (Fig. 7).Some of the plants wereobserved growing with another succulent, Aeoniumleucoblepharum (Crassulaceae;one of just two species of thisgenus occurring in East Africa;Fig. 8).  Some plants were alsogrowing together in closeassociation with another highaltitude Aloe, namelyA. debrana (Fig. 9), disting-uished, for instance, by havingprominently-toothed leaves(Verdoorn & Christian, 1947; Reynolds, 1966).  Thisassociation between these two high-altitude-growingaloes has already been recorded (Sebsebe Demissew &Nordal, 2010: Fig. 41).  However, no hybrids betweenthese two species have, as yet, been observed.Relatives of Aloe pulcherrimaAs mentioned earlier, 93% of Ethiopian and Eritreanaloes are high altitude species, and indeed A. pulcherrima grows at exceptionally high altitudes.The closest relatives of A. pulcherrima are A. ankoberensis Gilbert & Sebsebe and A. steudneriSchweinfurth, both cliff-dwelling (cremnophytic)Ethiopian endemics.  A. pulcherrima differs from theseother two species which have the following features: theyoffset from the stem base (ie lack dichotomous branching);have leaves that are not or are only slightly glaucous; haveleaf margins with prominent teeth over 2mm long; andbrown (not purple) dead leaves (Sebsebe Demissew &Nordal, 2010).  All three species have the characteristicU-shaped peduncle of the inflorescence: the peduncleinitially grows downwards, then turns upwards to produceerect racemes (Fig. 3).  All three species also flower in therainy season, July to September, unlike other high altitudespecies such as A. debrana which flower in the dryseason, from December to February (Gilbert & SebsebeDemissew, 1997; Sebsebe Demissew & Nordal, 2010).This difference in flowering seasons for A. pulcherrimaand A. debrana undoubtedly accounts for the absence ofhybrids between these two sympatric species.ACKNOWLEDGEMENTS:I am deeply indebted to Janet Haresnape of the School of Life, Healthand Chemical Sciences, The Open University, Milton Keynes, fortaking up my challenge of photographing Ethiopian aloes, and in particular for recording the serendipitous encounter with A. pulcherrima.  Her husband John is also thanked for ensuringJanet’s safety when photographing aloes for me often on precipitouscliff habitats!  My wife Marjorie is thanked for comments on an earlier draft of this article.LITERATURE:Carter, S, Lavranos, J J, Newton, L E & Walker, C C (2011) Aloes. Thedefinitive guide. Kew Publishing, Royal Botanic Gardens,Kew/British Cactus & Succulent Society. Edwards, S, Sebsebe Demissew & Hedberg, I (1997) Flora of Ethiopiaand Eritrea Volume 6.  The National Herbarium, BiologyDepartment, Science Faculty, Addis Ababa University,Ethiopia/The Department of Systematic Botany, UppsalaUniversity, Sweden.Glen, H F & Hardy, D S (1986) Aloe schelpei. Flow. Pl. Afr. 49: t.1935.Gilbert, M G & Sebsebe Demissew (1997) Further notes on the genusAloe in Ethiopia and Eritrea.  Kew Bull. 52: 139–152.Reynolds, G W (1961) A new Aloe from Ethiopia. S. Afr. J. Bot. 27:1–3, tt.I–II.Reynolds, G W (1966) The Aloes of Tropical Africa and Madagascar.The Trustees, The Aloes Book Fund, Mbabane, Swaziland.Sebsebe Demissew & Nordal, I (2010) Aloes and lilies of Ethiopia andEritrea.  Shama Books, Addis Ababa, Ethiopia.Sebsebe Demissew, Nordal, I & Stabbetorp, O E (2001) Endemismand patterns of distribution of the genus Aloe (Aloaceae) in theflora of Ethiopia and Eritrea.  Biol.  Skr. 54: 233–246.Verdoorn, I C & Christian, H B (1947) Aloe debrana.  Flow. Pl. Afr.26: t.1016.Fig. 9  A. pulcherrima growing in association with A. debrana, centre-left top (Photo: Janet Haresnape)Dr Colin C WalkerSchool of Environment, Earth & Ecosystem Sciences, The Open University, Milton Keynes, MK7 6AAEmail: c.walker702@btinternet.comLayout by Alice Vanden Bon135CactusWorld Vol. 35 (2)

<i>Aloe pulcherrima</i> - a beautiful Ethiopian endemic

Abstract

Similar works

Full text

Available Versions

Open Research Online (OU)