Bally,P. R. O.

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EAST AFRICAN SUCCULENTS.
Part1.
By P. R. O. BALLY.
Succulentshavebecomemoreandmorepopularwith the
amateurgardenerduringthelatteryears;athometheyarebeing
increasinglygrowninhothouses,or,onasmallscale,theyadorn
manyashelteredwindow.si1l.In warmerclimates,wherethey
needlessprotectionfromtheseverityof rainandcold,Succu-
lentsdoverywell in rock-gardens.
EastAfricahasclimaticconditionswhichespeciallyfavour
thecultivationof Succulents-exceptin the higheraltitudes
above6,000feetor in thoseraredistrictswithregular,heavy,
rainfalls..
Manyamateurgardenerstakegreatpainsto import·CactiandotherSucculentsfromAroericandfromSouthAfrica;they
seemtobequiteunawareofthefactthatEastAfricapossessesa
wealthof beautifulindigenousSucculentswhichcanwellbear
eomparisonwithanyoftheimportedplants..
Withits-IDOdestrequirementswithregardto rainfallandto
soilconditions,theSucculentgardenis oftentheonlypatchofglori usabundanceandof gaycoloursin thelistlesslull of the
dry season,for Succulentswill thrivewheremostotherplants
woulddieofstarvationorof exposure..
What,exactly,areSucculents?Thetermis usedcommonly
withoutdiseriminatlonalongwiththatof "Cacti" in orderto
designateallfleshyplantscoveredwithspines.Thisisamistake,
fortheterm"Cactus'I (plural"Cacti,"alatinizedwordderived
fromtheGreeknoWlII kaktos,"thespinycardoon)appliestome b rsofonefamilyofplantsonly,theCACTACEAE,mostof
whichhaveindeedevolvedintofleshy,leaflesshapes,'whichare
coveredwithclustetsof spines.A fewmembersof theCactus
familyhowever,.liketheGenusPeireskia,donotlookliketrue
Cactiat all;they arewoody,spiny,shrubswithfairly large,
ordinaryleaves;theexpertonly, who studiesthe anatomical
characteroftheirflower,knowsthattheybelongtotheCactaceae.
The term "Succulents"has a muchwider significance
(" succulent"standsfor" juicy,"andit isderivedfromtheLatin
noun II succus,"juice). It includesall plantswhich have
developeda capacityfor storingwaterin variouspartsof their
frame,regardlessof theirplacein thenaturalplantsystem.
Thusit is correcto saythatthefleshyCactiareSucculents,
but it is a mis-statementto callall Succulents:Cacti.
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PLATE 7.
FIG. 1. FIG. 2.
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FIG. 5.
Typical representativesof succulentforms; for explanationvide text.
Strictlyspeaking,beets,potatoes,onionsandall otherplantswith bulbousandtuberousrootsshouldalsobe termedSuccu-
lents,but for practicalpurposesthemeaningof the term has
beenlimitedto suchplantsasstoretheir reserveof moisturein
anypartof theirstructureshowingaboveground,andwhich~
by reasonof thiscapacity-assumestrangeand bizarre shapes
whichset themdefinitelyapartfrom the bulk of the so-called
normalvegetation.
Storageof water becomesnecessarywhere its supply is
irregularor lackingfor longperiods,wherethesoil is porousor
scarce,andwhereevaporationis high. As mightbe expected,
Succulentsarefoundmostlyin ariddistricts,on rocks,in deserts,
aJld in otherlocalitiespresentingsimilar conditions,which are.
foundsometimesevenat high altitudes.
MostSucculentspossessacomparativelyweakandsmallroot
systemandtheyarethusunabletopenetratedeepdownintothe
moisture-ladenstratafromwhichthesurroundingdesertvegeta-
tion maydrawduringthegreaterpartof theyear.
They mustneedsmakeup for this deficiencyby someother
qualityin orderto survive, and this quality is preciselythe
storageof wateragainstthelongperiodswhen.itis notavailable
to themfromextraneousources.. They havethusemancipated
themselvesto suchanextentthattheysubsistwherenosubsoil
waterispresentandwhereothertypesofvegetationwill notlive.
SomeSucculentshavedevelopedthe facl,lltyof survival
withoutexternalwatersupplyto a pointwhichis truly astound-
ing. Mostwill live.on for months,somefor years. True, we
areconversantwith thisphenomenoni thecaseof bulbs,tubers,
evenwith ourcommonpotato;butthesearewell definedcentres
of growth,while with mostSucculentsthe powerto surviveis
inherentin all part~of the plant independentlyand in various
degrees;a singleleafof Bryophyllumfor instancewill giverise
to do.zensof youngplants..
At thebeginningof lastyearI despatcheda consignmentof
succulentEuphorbieae-mostlysmallcuttingsanda few imma-
ture plants--all packedin a dry state,wrappedup in paper;
althoughtheconsignmenthadbeenunderway for well overtwo
months,on~yfour outof seventy-fivediedduringthatperiod.
Cuttingsof a Synadenium-whichI had left tied up in a
bundlein a dry cornerof the botanicalroomat the Museum,
startedto developshootsandleavesaftera periodof apparent
deathof fully eightmonths,andwithoutanyvisibleprove<::ation.
The mostastoundingexampleof the survivingpowerof a
SucculentI havecomeacrossin theBerlinMuseum:a seemingly
dead plant of Hbushman'scandle" (Saraocaulonrigidum,
7
GERANIACEAE) fromSouth-WestAfricahadbeenkeptthere
lockedupin adrawerfor anunknownperiod,butcertainlyfor
severalyears. It wasthenplacedinto a showcaseat the
Museum,and,afterhavingbeenanexhibitundergl~ssforthree
furtheryears,it startedtoemityoungshoots.Transferredtothe
hot-house,theplantcontinuedto developnormally,seemingly
nonetheworseforitslongperiodofapparentdeath. Incredible
asthismayseem,in thehabitatof thisplantperiodsof drought
of sevenyearshavebeenrecorded.The" bushman'scandle"
withits poorlydevelopedrootsystemandwith little facilities
for absorptionof theheavydewswhich occurin the desert
districtsof South-WestAfrica,is thicklycoveredwitha layerof
resinouswaxwhichis completelyimpermeableandwhichthus
keepsits vital partseffectivelyprotectedagainstevaporation
untilconditionsprovideperiods-rareandbrieftheyare-which
permitof thedevelopmentof tinyleavesandof itspropagatory
organs.
It isacuriousfactthatSucculentswhichbelongtoentirely-
differentfamiliesandwhicharethusbynomeansrelated,often
assumeanoutwardresemblancewhichmakesit difficultotell
themapart.
A botanistwhohadtravelledextensivelyin Mexicoaswell
asin EasternAfricashowedmephotographswhichwereseem-
inglytakeninoneandthesaIl\elocality;onlyaverycloseinspec-
tion revealedthat someof the picturesrepresentedMexican
CactiandothersEastAfricanEuphorbieae.If thetwoplantsdid
notoccurin twodifferentcontinents,thisresemblancewouldhave
madeanidealobjectforthesupportersof themimicry-theory.
Suchoutwardresemblanceis moreprobablydueto analo-
gousclimaticandgeographicalconditionswhichtendtoevolve
certainfeaturesbestadaptedtoendure.
An interestingexahlpleof similarityof appearanceis,
recordedonPlate6,whichshowsacomparisonof thegrowthsof
Monadeniumstapelioides (Euphorbiaceae),Huernia aspera
(Asclepiadaceae),and of Notonia petraea(Compositae).All
threeplantsoccurin thevicinityofNairobionthesametypeof
rockyground. Theresemblanceis confinedto theiroutward
appearance,for theyarenotin theleastrelated.
In spiteof thefrequentoutwardsimilarityof succulentsof
differentorigin,wefindmuchdiversityof appearanceamong
them,thoughalwaysonthelinesof theonedominatingprin-
ciple: economyin waterconsumption.This aim is reached
mainlyby reducingthesurfaceof evaporationto a minimum,
whilepreservingatthesametimethechlorophyll-coveredsur-
faceswhichareessentialfor maintainingmetabolism.Theoreti-
callytheidealSucculentwouldthuspresentasphericalshape,
8
with its surfaceadaptedfor assimilation,and this extremede-
velopmenthasindeedbeenreachedby certain globular Cacti
fromMexico,bytheSouthAfricanEuphorbiaooesaandby some
South-WestAfrican Mesembrianthemum.spp.
Nature has, however,a variety of ways for achievinga
similar aim, and anothertrendof adaptationis representedinthe abovementioned"bushman'scandle": here, the plant is
coatedimpermeablyand has adapteditself in sucha manner
that the rare emissionof leavesafterexceedinglylongperiodsof restis sufficiento safeguardcontinuityof life.
OtherSucculentshavesolvedtheirproblemin otherways,
andwethusfindthatalmosteverypartof theplantcanbemodi-
fiedfor the storageof water. It followsthat Succulentsmay
assumea verygreatvarietyof shapes:theymaybeclassedinto
the followingmain categories,althoughit is pointedout here
thatthisis bynomeansascientific lassification,its onlypurpose
beingto illustratethevariousformswhichmaybe metwith in
EastAfrica. OnPlate7 atypicalrepresentativeof eachof these
formsis shown.
Modifiedparts.
(1) Trunk only.
(2) Trunk andbranchesonly.
(3) Branchesandleaves(the latter
well developed).
(4)Trunk andbranches,while leavesare
greatlyreducedanddeciduous.Spiny
or spineless. Inflorescencefleshy.
Turningwoodywith age.
(5)Wholeplantincludinginflorescence
fleshy,withoutwoody's~ructure.
RepresentedonPl. 7by
Cissussp.
Aden-iurncoeta1teum
Cotyledon.barbeyi
Euphorbia b"'1tll1t4ar=
C;\l'aIlUlllJ ,UUll:rr~I1C,\ [m:
SMeelieS9~Qtq
Althoughit mightbe temptingto basea descriptionof Succu-
lentson theaboveexternalcharacters,it will bemoresatisfac-
toryandmoreinstructivetodescribethemaccordingtotheplace
whichtheyholdin thenaturalsystem,i.e. in theirphylogenetic
order.
The familiesmostprolificin succulentformsin EastAfrica
ate EUPHORBIACEAE and ASCLEPIADACEAE. Other
families, like CRASSULACEAE and AIZOACEAE, though
representedby numerouspeciesin the Southof theCClmtinent.
areknownby a fewspeciesonly fromEastAfrica,whileGERA-
NIACEAE, to which the above-mentioned"bushman'scandle"
belongs,havenot producedoutstandingsucculentformsin our
partof theworld.
9
COMPOSITAE.
LABIATAE.
LILIACEAE.
ARACEAE.
MORACEAE..
ICACINACEAE.
AMPELIDACEAE.
APOCYNACEAE.
ASCLEPIADACEAE.
On theotherhand,someeuphorbiaceousGenera,like Stena-
denium,Synadenium,Monadenium,andDorsteniaareconfined
almostexclusivelyto EasternAfrica.
Thefollowingdescriptionsdonotclaimto includeall Succu-
lentsto be foundin EastAfrica; thefloraof thiscountryis far
too imperfectlyknownfor suchan undertaking,nor has the
authorhadaccesstoall literatureonthesubject,andeveryyear
newspeciesarediscoveredto increasean alreadygreatvariety.
This lack of completeness,however,addsratherthandetracts
fromthe charm·of this interestinggroup, for every lover of
naturehasit within his reachto makediscoveriesof his own.
The aimof this paperis mainly.to stimulatetheinterestin
collectingand cultivatingEastAfricanSucculents,andto dis-
provetheoftenheardcontentionthattheycannotbearcompari-
sonwith thoseof othercountries.
EAST AFRICAN SUCCULENTS ARRANGED IN THEm NATURAL ORDER.
Families. Genera.
CRASSULACEAE.Cotyledon, Crassul~,Kalanchoe,Sed1.1ai.
AIZOACEAE. Mesembrianthemum.
PORTULACACEAE. Portulaca,Talinum.
PASSIFLORACEAE. Adenia.
CUCURBITACEAE. Momordica.
CACTACEAE. Rhipsalis.
EUPHORBIACEAE. Euphorbia, Monadenium,Stenadenitim,
Synadenium.
Dorstenia.
Pyrenacantha.
Cissus.
Adenium.
Caralluma,Ceropegia,Cynanchum,Du-
valia, Echidnopsis,Edithcolea,Huemia,
Sarcostemma,Stapelia.
Kleinia, Notonia,Senecio.
Aeolanthus.
Aloe, Anthericum,Bowiea,Sansevieria.
Zamioculcas.
CRASSULACEAE. (Plate 8.)
This family is .widely distributedoverhotandtemperate
countries. The centreof its distributionis in Africa, but repre-
sentativesarefoundaisoin AustraliaandPolynesia,a veryfew
mSouthAmerica.
In the NorthernHemisphere,includingEurope,it is repre-
sentedby the·GeneraSedu'mandSa:rlfraga.
The Generafoundin EastAfrica are: Cotyledon,Crasittla.,
Kalanchoe.Sedum.
10
Cotyted01t.
The genusis representedwith over thirty spctCiesin South
Africa, while only two areknownfromEastAfrica.
CotyledonBarbeyii,Schweinf.
Hasa widedistributionin EastAfrica, whereit is endemic.
It hasbeencollectedfromsouthof Kenla Colonyasfar north1&
Erythrea. It is one of the mostornamentalof East African
Succulents,a vigorousshrubthat mayattaina heightof seven
feet. The erectbranchesbearlarge,fleshy,roundedleavesof a
freshgreen,powderedwith a slightwaxy bloom. The flowers
rise on a slendetstemin a graceful,somewhatdrooping,cyme
of bell-shapedflowerswhich rangefroma palelemon-yellowtA>
aglowingvermilion.
Plate 7 (3)-whole plant. Plate 8 (I)-flowering branch.
Cotyledonumbilicus,L.
The distributionof thisspeciesis very wide indeed;it is
known to occur in Britain, in the CanaryIslands,in North-
WesternAfrica. In EastAfrica theplanthasbeenfoundin the
alpinezonesabove10,000feetof mostof the highermountains;
it is a small,succulentherb, rarely overa footin height. The
small, bell-shaped,flowers are greenish-white,standingout
almosthorizontallyfrom a single, sometimesbranched,stem.
which risesfrom a rosetteof fleshy, disc-shapedleaveswith
notchededges,attachedto the stalksin the centre. The plant
is not a,truly xerophyte,but seemsto pre!erdampplaces;it is
foundmostlyonmossyrocksnearmountamstreams.
Crassuta..
Morethantwo hundredspeciesof the mostvariedappear-
anceareknownfromSouthernAfrica, while thespeciesknoWR.
from East Africa are far lessnumerousand in mostcasesless
showy. They aresmallherbs,with few exceptionsmorethan
a few incheshigh, wi~hsmall,sometimes.minute, star-shaped
flowers,whichgroweithersingly-Qnslenderstalksfromtheleaf-
axils,or in denseclustersfrom a mainstem.
Crassulaabyssinica,A. Rich.
Is widelydistributedover tropicalAfrica. It is oneof the
tallestandmostrobustmemberof thefamily,attaininga height
of 21feet. Thesinglestem,whichis branchedtowardsthetop,
carriesa denseclusterof small,star-shaped,white or purple,
flowers. The fleshyleavesarelancet-shapedandminutelysaw-
edged. Theyarearrangedaroundthestemin sucha way that
thelargerleavesforma kind of rosetteatthebasebecomingless
numerousand smallerastheyascendthe stem. (Plate8 (2a).)
11
Cra8sulaalsinoides(Hookf. Engl.).
Wasfirstdiscoveredin Cameroonbut was foundlater to
extendall overtropicalAfrica,includingEastAfrica. It is a
herbwith fleshy,oblongleaveswhicharedottedwith small
maroonspots.Theflowersarestar-shaped,white,andsome-
whatfleshy,andgrowsinglyonslenderstalks,fromtheleaf-
axils. Theplantgrowsseldomhigherthanabouteightinches.
Verynearlyrelatedtothisspeciesare:-
,Crassula,coleae,Bak.,whichis commononrocksin Kenya
Colony(Plate8 (2b).);
Crassulagalunkensis,Engl.,withslightlynarrowerleaves;
Cra8sulavolkensii,Engl.,fromLakeDschallainTanganyika,
amorerobustspecies,growingtonearlya footin height;and
CraBsulanakurensis,Engl.,whichis foundonrocksaround
LakeNakuru.
Cra8sulacra8sipes,C. A. Smith.
Crassulapharnaceoides(Hochst.),Fisch.etMey.
Cra8sulaparvijolia,E. A. Bruce, .
andrelatedspecieshowyetanothertypeof appearance: the
small,narrow,fleshy,,leavesarearrangedverycloselyin oppo-
site alternatingpairs,which givethe branchesan outward
resemblancetoclub-mosses.Noneofthemgrowverytall;they
havesometimestheappearanceto miniaturetreesof lessthan
a foothighandarequiteornamentalin a rock-garden.The
flowersareminuteandnotshowy.OnPlate8 (2c)a Cra8sula
sp.belongingtothistypeisshown.
Cra8sulaerubescens,Bullock,fromMt.Elgon,growingonrocks,
isa verysmallherb,barelytwoincheshigh,withbrightscarlet
foliage;it hassmallJ single,cream-colouredflowers.
Crassulaaquatica,L. ,
Cra8sulapentaneira,Boyle.
Cra8sula.Wrightiana,Bullock.
All occurin E. Africa,theyarealsosucculentherbs,butas
theirhabitatis mostlyin swampsandbogsandin otherdamp
places,theyareoutsidethescopeofthispaper,whichdealswith
Succulentssuitablefor rockgardens.
KALANCHOE.
Thisgenuswhichis veryrichin formsis distributedover
thetropicalandsub-tropicalpartsof Asia andMrica. It is
representedby a numberof very ornamentalspeciesin East
Africa. They are sturdy,very succulent,herbs,s.ometimes
attainingaheightofsixfeetandover,growingoftenin clumps.
12
PLATE 8.
FIG. 1. FIG. 2.
FIG. 3. FIG. 4.
CRASSULACEAE.
Thefairlylargefour-petalledflowersgrowin densecymesona
tallstem.Theirrangeofcolouris wide. White,cream,yellow
in manyshades,salmon-pink,brick-red,and scarlet-flowering
speciesmakeKalanchoeadesirableplanUnrockgardens.Even
whennotin flower,thefleshy,oftenshowilymarkedleaves,are
veryattractive.
Kalanchoecrenata,Haw.
A tall, succulentherbupto 5 feet,whichis widelydistri-
butedovertropicalAfrica. Thefleshyfoliageisofarichglossy,
green,sometimeswithanarrowmaroonedge,theflowersprim-
roseyellow. It is commonaroundNairobiandseemsto prefer
the lightshadeofforestedgesandof highgrass.
Kalanchoeglandulosa,Hochst.
Commonin theNgongHills onpoorrockysoil,thisplant
rarelyattainsa heightof morethan16inches. Theradical
leavesat thebasearenomorethantwoincheslongand!inch
wide,andtheydiminishin sizealolJgthe stemof the plant,
whichbearsa clusterof primrose-colouredflowers,risingfrom
fleshy,globula~,caliceswhichare,like therest of the plant,
coveredwithfine,rathersticky,hairs. (Plate8 (3).)
Kalanchoeglaucescens,Britt.
Oneof themostattractiveof indigenousKalanchoes.It is
mostlyfoundin clusterswhichpresenta mostpleasingaspect
whenin full bloom. Themedium-sizedleaveshavenotched
edgesofa deepmaroon,whiletheir greensurfaceis covered
withabluish-greenbloom.Thefloweringstalksrisetoaheight
of overtwofeetwheretheyforma massof coral-redflowers.
Thoughsmallin sizeindividually,their numberand.bright
colour,contrastingwiththeblue-greenof theleaves,producea
verygoodeffect.Theplantis commonin theNgongHillsand
onLukenya,nearNairobi.
Kalanchoelateritia,Engl.
Notunlikein appearancefromKalanchoeglaucescens,this
specieshassmallerflowerswithnarrowerpetals,nor are the
floweringheadsodense.Theflowersare,however,morebril-
liantlycoloured,a brightvermilion. It preferslow andhot
districtsandisfoundin thecountryextendingfromKilimanjaro
to·theTeitaHiUs.
KalanchoeLugardii, Bullock.
A tall, apparentlywidelyspread,Kalanchoe,whichattains
a heightof over5feet. Theflowersmeasureaboutoneinchin
13
diameterandseemto vary'muchin colour,but purewhiteand
yellowseemtobepredominant.Theleavesarelargeup to nine
incheslong and five incheswide, the notchedmarginsmarked
with maroon. The plant hasbeenfoundfrom MountElgonat
7,500feetto Lake Rukwa in Tanganyikaat various altitudes
downto 4,900feet. (Plate 8 (4).)
Kalanchoepetitiana,A. Rich.
Is verysimilarto Kalanchoecrenata,excepthatleavesand
all greenpartsarequitesmooth. The distributionis approxi-
matelythesame.
Kalanchoesomaliensis,Baker.
Thegiantof EastAfricanKalanchoesoccursquitecommonly
in Nairobi district on old cultivatedland. It wasprobably
introducedin Kenyaby Somalicattleandhorsedealers,and it
is now firmlyestablishedhere.
The large,pale-greenleavesaremottledwith maroonand
they cling to the thick, sturdystalk at its base,rather in the
fashionof cabbageleaves,while higherup they are set more
looselyin oppositepairs.
Theflowerheadsarelarge,andsoaretheindividualflowers,
which arewaxy-whiteandattaina diameterof 1iinches,their
tubebeingtwo incheslong.
Kalanchoesp.
In thehalf-shadeof shrubsandtreeson the NgongEscarp-
ment and on Lukenya behind Athi River station occursa
Kalanchoewhich differsfrom all othersby its finely divided,
thoughfleshy,leaf, which makesit an attractiveplant in the
rock-garden.The flowersaresmalland ivory-white,and they
aresetoffverywell by thebrilliant emerald-greenof thefleshy
leavesandstalks.
SEDUM.
The Genusis but poorlyrepresentedin East Africa, and
apparentlyconfinedto the higherregions.
Sedumruwenzoriense,Baker.
A smallsucculentherbof decumbenthabit which grows
mostlyepiphyticallyin treesor on mossyrocks. Theleavesare
distributedlooselyall alongthe stem;theyhavethe sizeand
roundedshapeof hulled rice. The flowersgrowat theendof
thebranchesin ratherdensecymes.Theyarefive-petalledstars
of a brilliant goldenyellow,anda plantin full bloomis a very
attractivesight..
14
Sedum MeyeriJohQ:nni8, Engl.
fromMt. Kilimanjarois a plantof appearanceand habits
verysimilartotheabove.
ThisconcludesthedescriptivelistoftheCrassulaceaewhich
arerepresentedin theHerbariumof the Coryndon.Memorial
Museum,andalthoughit is bynomeansa completerecordof
all EastAfricanspecies,it is hopedthatit will conveyto the
readerafairideaoftheappearance,thehabitsandthedistribu-
tionof thisfamilywithoutbotheringhimundulywith highly
technicaltermsor descriptions.
(Tobecontinued)
15


East African Succulents, Part I

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East African Succulents, Part I

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