S
ometreesappeartosleepat
night,dippingtheirbranchesa
littlefromduskuntildawn.It’s
abeautifulthought,butdon’tbe
fooledintothinkingallisrestandrelaxation
inthegardenafterdark.Mostplantsare
busybrewing,measuringandseducing,as
iftheirlivesdependonit.Whichtheydo.
Manyareabletotrackthelengthofthe
night,sotheycansynchroniseflowering
withpeakpollinatoractivityorother
environmentalnecessities.Thoseflowers
andtheirpollinatorsareoftenoutand
aboutattwilight,orinthemoonlight.
Forexample,thepale-colouredflowers
ofnightjasmineandsweetpittosporum
producetheirmostpotentscentsinthe
evening,whenmothsareinfullflight.
Insomeareas,plantsusethenightto
preparefortoughtimesahead.Desert
succulents,forexample,soakupcarbon
dioxideatnight,sotheycansealtheir
leavesshutduringtheheatoftheday.
Butthere’sadarkersidetothenightlife
ofsomeplants.Takethegiantwaterlilies
(VictoriaamazonicaandV.cruziana),
championedbyDavidAttenborough.
TheseSouthAmericanbeautiesprovide
whatcouldbedescribedasa‘compulsory
bedandbreakfast’fortheirinsectguests.
Asnightfalls,thelargewhiteflower
emergesfromtheshallowwater,warm
andsweet-scented.Amazonianscarab
beetleslovethismix,andareattracted
insidethebloom,wheretheysoonbecome
preoccupiedwithfoodandsex.Asdawn
approaches,theflowercloses,trapping
thebeetlesuntilthefollowingevening.
Nextevening,thefloweropensagain,
thistimepinkandodourless.Atfirst,
itremainswarm–atleastaroundthe
pollen-bearingstamens–butasitcools,
thesatiatedbeetlescarryoffpollenthat
hasbrushedontothemduringtheir
night-timescrambling.Theythendeposit
thisontothereceptivepartofthenext
white,scentedandwarmbloomtheyfind.
Meanwhile,thepinkflowerisdrawn
belowthesurfaceofthewaterwhere,if
successfullypollinated,theseedwillform.Thisself-warming,calledthermogenesis,
isfoundinotherwaterliliesandthelotus.
There’salsothecycadcone,whichheats
upintheeveningtoattractpollinating
weevils,andthemassiveandstinking
floweringapparatusofthetitanarum
(Amorphophallustitanum),whichprovides
acosynight-timenookforcarrionbeetles.
Alloftheseplantsgetacompetitive
advantage(throughmoregeneticvariety)
fromcross-pollination,ratherthanfrom
self-fertilisation.Thisoffsetstheenergy
costofprovidingawarmbedforthenight.SENSEAPPEAL
Batsareattractedtoflowerswithstrong
coloursandoftenmustyodours,rather
thanawarmdisposition.Gardenersin
thetropicsandsubtropicswillbefamiliar
withtheuntidy,blood-redflowersof
thesausagetree(Kigeliaafricanasyn.
K.pinnata),andbananas(Musaspp.),
withtheirlarge,purplishbractswrapped
aroundclustersofyellowflowers.
MorewidespreadinAustraliangardens
istherobustclimbercalledcupofgold
(Solandramaxima),whichfeaturesbold
yellow,trumpet-likeblooms.
Youareunlikelytofindthisoneinan
Australiangarden,butMucunaholtonii,
aCentralAmericanvine,hascurved
petalstoreflectthehigh-pitchedping
usedbybatstofindtheirwayaround.
Thiscleveradaptationenticesbatsin
topollinateitsgreen-colouredflowers
amongthekaleidoscopeofcolourand
movementinatropicalforest.
Therearenumerousdistractionsfor
pollinatorslivinginourcitiesandtowns.
Remnantbushlandreliesonanassortment
ofnocturnalvisitors,suchasbats,moths
andvariousmarsupials.Thereisemerging
evidencethatartificialilluminationin
oururbanareasisdisruptingthesevitalrelationships,soyoucanhelpbykeeping
youroutsidelightingtoaminimum.NOSUNREQUIRED
Intherelativequietofthecountryside,
thereareplantsthatliveandreproduce
entirelywithoutlight.Themostfamous
ofthesearetheundergroundorchids
(Rhizanthellaspp.),foundeverynowand
then(bychance)inWesternAustralia,New
SouthWalesandsouthernQueensland.
Anunrelatedgenusofplantscalled
Thismialivesentirelywithintheleaflitter,
withmorethan 50 speciesoccurringin
theAmericas,AsiaandtheAustralian
region.I’veseenfairylanterns,astheyare
called,onlyonceinnature–inVictoria’s
OtwayRanges–andafewtimespickledin
jarsintheNationalHerbariumofVictoria.
Generally,these‘underground’plantsare
discoveredbyfarmerscultivatingnewland
orfollowinganuntidyanimalscratching.
Fairylanternshavenogreenleaves
and,therefore,noneedtobeexposed
tothesun.Alltheirfoodissourcedfrom
mycorrhizalfungigrowingnearby.The
brightredflowersareprobablypollinated
byinsectscrawlingthroughtheleaflitter,
andseedisspreadbythesamebugsor
rummagingmarsupials.
Althoughyouareunlikelytofindafairy
lanterninyourhomegarden,youmightsee
oneofourlocalparasiticplants,suchas
broomrape(Orobanchespp.),growingoutof
themulch.Thebrownishorpurpleflowers
emergewithoutgreenleavesorshoots,so
havenoneedforsunlight.Somespecies
arepestsinagriculture,butwedohavea
nativevariety(O.cernuavar.australiana).
Ofcourse,thehostplants,andindeed
mostplants,needlotsofsunlighttothrive.
Theirlives,andours,dependonit.When
thelightsareoff,though,there’sstillplenty
PHOTO goingoninthevegetablekingdom. GA
ISTOCK
CURIOSITIES
GARDENING AUSTRALIA MAY 2019 43
ere’s a darker side to the nightlife of some plants. Take the
giant waterlilies, championed by David Attenborough. ese
South American beauties provide what could be described
as a ‘compulsory bed and breakfast’ for their insect guests.