chusquea - mountain bamboo of latin america

8/6/2019 Chusquea - mountain bamboo of latin America

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PlantsmanThe

Chusqueamountain bambooof Latin America

Chusqueamountain bambooof Latin AmericaGIB COOPERgives an overviewof the available species and cultivarsand encourages gardeners to try

some recent introductions

BAMBOOS ARE POPULAR PLANTS

loved by many in theWestfor the exotic touch these

giant grasses offer in the garden.

There are about 1,400 species withabout one third being native to theAmericas. These 460 species rangefrom the southeastern United Statesto the tip of South America. Thisgroup is divided into the herbaceousbamboos with about 115 species andthe woody bamboos with 22 generaand approximately 350 species.

Within the woody bamboo groupis the spectacular genus Chusquea(from the native Andean name

chusque), the most widely grownhardy American bamboo in ourgardens. More than 40 percent ofAmerican bamboo species belongto Chusquea. The habitat of thegenus is predominately the Andesand the other mountain rangesdividing the American continentsinto eastern and western slopes.These mountains stretch fromMexico to the inland borders ofArgentina and Chile, and over to

eastern Brazil. However, someChusquea species live in the warmertropical lowlands and hills.

Among gardeners familiar withbamboo, most love the look andutility of the chusqueas. ManyAsian bamboos such asPhyllostachys,

Pleioblastus and Semiarundinariaare also beautiful but may createa maintenance problem withunderground rhizomes thatrelentlessly spread away from the

plant and cause the loss of preciousgarden space to a bamboo grove.Chusquea are favoured for theirwell-behaved, clump-forming habit.However, several Asian generasuch asBorinda,Fargesia,

Himalayacalamus and Thamnocalamusare similarly well-behaved.

Chusquea giganteahas been masquerading incultivation under other names. This specimen isin a UK garden; it will grow taller than C. culeou

DavidWilson

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Genus characteristicsMost chusqueas are relatively new tohorticulture, but others like C. culeouwere first introduced in the late 19th

and early 20th centuries. Thanks tothe scientific collection activitiesof Friedrich Schlegel-Sachs, LynnClark, Gilberto Corts and GeraldBol, many additional species arenow growing in European andNorth American gardens.

The basic characteristics definingthe genus are solid culms, multipleand dimorphic branch buds at eachnode, culm leaves lacking bothfimbriae and auricles, and a base

chromosome number of x = 10(Clark 1997). The group is dividedfurther into subgenus Chusquea,subgenusRettbergia and subgenusSwallenochloa. The last contains thehardy species familiar to mostgardeners, native to the ruggedhigh-altitude terrain and southernlatitudes of South America. Thissubgenus contains three speciescomplexes the C. heterophyllagroup, the C. nudirameagroup

and the C. culeougroup. However,the taxonomy is still volatile.

TheChusquea culeouspecies complexThis complex consists of threegenerally recognised but closelyrelated species: C. culeou, C. andinaand C. gigantea. All of these are or may have been cultivated inWestern gardens. Native to higherelevations in the deep southern

Andes in both Argentina and Chile,they are some of the hardiest species.The species are separated primarilyon differences in size and branchingtypes, as the flowering structures arevery similar. However, assessment ofbranching characteristics in a gardensituation, especially on young plants,is not an easy way of determiningidentity. Other factors appear toinfluence the apparent variation

observed in the field and garden,notably, altitude, latitude, wind,moisture, soil type, temperature andwhether growing in full sun or shade.

As a result, the naming of speciesin this group is rather confused dueto misidentifications and incorrectusage of some names. Also, thebotanical status of these speciesis still in a state of flux. A recentarticle by Triplett & Clark (2003)describing the difficulties ofdifferentiating between the speciesspeculatively summed it up, Thequestion remains as to whetherthe named entities of the C. culeou

group are variants within a speciesor independent lineages that shouldbe considered distinct species.More recently, Dr Lynn Clark (pers,comm.) surmised, What I think isthat we are seeing a highly variablespecies in the process of ecologicaldifferentiation, that is, speciation.Based on all the data so far, thesouthernmost chusqueas (at leastsome of them) probably got there

fairly recently (in geological terms)and thus havent had as much timeto evolve. This is not unlike thesituation with C. foliosa, C. tomentosa

and C. subtilis in Costa Rica.She feels the topic needs moreresearch and fieldwork inArgentina and Chile.

This article deals with the speciesand variants from the C. culeoucomplex currently recognised inhorticulture, along with a few otherhardy and not so hardy species.

Chusquea andina

This species is always found above

the tree line at some of the highestelevations in the Andes. Skiersat several Chilean and Argentineresorts may see this small 1m-highshrubby grass poking throughthe snow or growing in patchesof open ground.

Whorled around each culm isa tight mass of short branchesand leaves. The thick leaves are astriking pale blue-green. However,

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GENUS PROFILE

Chusquea andinais usually seen in the wild as a short species that thrives above the snowline.In cultivation it becomes a taller, more substantial plant and it is expected to be very hardy

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in cultivation it forms a larger plantwith larger leaves and branches.While still new to horticulture, it isexpected to be very cold-hardy.

Chusquea culeou

Typically reaching a height of 4mor more in gardens, and up to 7min ideal conditions, this is bestdescribed as the medium-sizedrepresentative of this group of threespecies. Its common name is foxtailbamboo. For many years it has beenthe commonest Chusquea in gardens,and now even more so since theraising of thousands of seedlings

from the mid to late 1990s. Theseresulted from the flowering ofimports brought to the USA andEurope a few years earlier.

The general habit is of an erect,vase-shaped clump imagine anarched foxtail or upright feather-duster arranged in a vase. Themedium-dark green foliage isthickly arranged on the culm,borne on whorls of 2030 equal

size branches at each node. The newshoots emerging from the soil varyfrom green to burgundy-red andthe first-year culms may be purplish-

black, ruby and green with tan linesafter the culm sheaths have changedto white and fallen off. The culmsmature to a light yellow-green withdark green nodes, a common featureof many chusqueas.

Leaf kill hardiness is consideredto be -16C, but this may vary inthe newer plants raised from seed.Synonyms include C. breviglumisand C. argentina.

C. culeou Caa PrietaThis cultivar is sometimes describedas a black bamboo due to the roastedcoffee colour of the culms andcontrasting white sheaths. It cangrow to a height of 5m or more. Theleaves are a darker shade of greenthan the typical species, closer to apine green than any other bamboo.This is a very ornamental Chusqueaand deserves high positioning in the

horticultural bamboo hierarchy.This bamboo has been incorrectly

listed as C. montana and C. nigricans;the latter is probably a synonym

of the former.

C. culeou Hilliers formThis group of seedlings were raisedin the US from seed of the mostrecent flowering in the UK. Theyhave been singled out due to theirshort branches and compact foliage.It is believed they will remain shortin stature and reach no higherthan 3m. Other similar seedlingsmay become named cultivars.

C. culeou f.longirameaThis form is very similar to thespecies but tends to have longer-necked rhizomes, creating morespace between culms. This resultsin a clump with a grove-like appear-ance. At present it is only cultivatedin a few locations in the US.

C. culeou TenuisIn the UK this is a short cultivar to

about 1.2m and the name may covermore than one clone. In the US,plants similar to this may be grownas Hilliers form. However, plantsgrown as Tenuis in the US havedistinctive erect leaves when grownin full sun. They are also a darkershade of green, approaching thatof Caa Prieta.

C. culeou Purple SplendourThis cultivar is noted for its purple

culm colour. It was selected by UKbamboo expert David Cromptonfrom a batch of seedlings. Thereare several other selections withthis attribute and time will separateout the best performers.

Chusquea gigantea

This recently recognised speciesis considered to be the largest,erect (non-scandent) Chusquea.

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PlantsmanThe

Chusquea culeouis the species most familiar to UK gardeners. It forms a handsome specimen withculms potentially reaching a height of 7m and the many small leaves giving a foxtail effect

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It is reputed to reach a height of 1518m with culm diameters of 56cmin its native Chile. The culms age toan attractive yellow. In contrast to

C. culeou, at each node there areusually 2 to 3 longer branches. LikeC. culeou it is very hardy, but newshoots have been damaged by frost.

It is faster growing than C. culeouand would need more space. Onceestablished and maintained, theresulting grove is both beautiful andutilitarian as a producer of fine poles.There is a thriving cottage industryin Chile using this species forfurniture and parquet floor material.

The name C. breviglumis hasbeen misapplied to this speciesand it has also been listed asC. aff. culeou. The current namewas coined by Demoly (1999),based on material grown in France.

Other hardy speciesSeveral other Chusquea species arereasonably hardy and worth tryingin the UK. Most make desirableplants but the scandent species,

though interesting, are in mostcases too overwhelming for theaverage garden. The following are allclassified within subgenus Chusquea,except for C. montanawhich is amember of section Swallenochloa.No members of subgenusRettbergiaare currently known in cultivation.

Chusquea cumingii

This is a densely blue-green foliagedChusqueawith a spidery, vine-like

habit. The leaves are small, thickand sharply pointed. A hedge of thisspecies is likely to be wider than tall,assuming a mound shape, with newculms arching up and out like spiderlegs. It is a terrific plant for openspaces, the coast and places needingan impenetrable privacy barrierlike that of a holly hedge. It isalso likely that a few new seedlingswill be entering the trade.

Chusquea macrostachya

The true plant has an arching habit,soft leaves and one larger branchat each node. It somewhat resemblesC. quila and the leaves are longerand narrower than those ofC. culeou.It is often mislabelled C. culeou buttaxonomically it is more closelyrelated to C. uliginosa than C. culeou.It is very difficult to propagate large divisions are the most success-

ful. Check your sources beforeattempting to acquire this species.

Chusquea montana

In nature this species is usuallyfound growing as an understoryplant. Its notable features arethe somewhat swollen nodes andshort stubby branches. Very fewspecimens are in cultivation and it isreported to be difficult to propagate.

A specimen believed to be thisspecies was seen by Dr Lynn Clarkgrowing in Peter Addingtonsbamboo collection at StreamCottage, West Sussex, UK.

Chusquea quila

This is a scandent species not oftenfound in cultivation. It is closelyrelated to C. valdiviensisyet isdensely foliaged like C. cumingii.

Most plants labelled as thismay be C. culeou.

Chusquea uliginosa

This is an arching species withlong, thin culms and small leaves.It colonises large areas by growingover other plants and, if grown inthe garden, it should be carefullysited. The species recently floweredand a few seedlings may be available.

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GENUS PROFILE

The culms of Chusquea culeouCaa Prieta age from orange-red to an attractive coffee brownand contrast effectively with the pale sheathes of the new culms. The leaves are darker greenthan typical C. culeou

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Chusquea valdiviensis

This species is not as hardy as those

listed above but is reputed to thrivein mild, west coast gardens in theUK and would be worth trying insheltered spots inland. It is thelargest of the scandent chusqueas incultivation the culms can reach25m in length. It has the ability tosprout recurved branches from thenodes, these allow the culms togrope through trees and hang on.This species is best planted near acliff-side or a large tree suitable to

support it. However, it is impossibleto pull out of a tree once it hasestablished in the canopy notfor faint-hearted gardeners!

Less hardy speciesIn the less hardy group, the daintyC. coronalis has fascinated a few

enthusiasts in West Coast USA

and the UK. This is because of itsdelicate little leaves held on shortbranches in whorls around slenderculms. The pompom look that thesecreate is an attribute found only inthis genus and a couple of others.Chusquea coronalis is very cold-sensitive, making it a conservatoryplant for aficionados.

A surprise from southern Brazilis C. mimosa subsp.australis, a newsubspecies showing some potential

in colder climates. Reports fromthe UK and USA are encouraging inthat it has survived -7C. It has a vase-like habit with arching, 5m culms.The central branch at each nodeis much longer than the others andthe fine leaves held on pink-tingedbranches lead it to resemble theless-hardyC. coronalis.

Though only a little less hardy,C. acuminata, C. circinata, C. foliosa,C. glauca, C. longifolia, C. pittieri,

C. subtilis, C. sulcata and C. tomentosathrive in moist, maritime climates aslong as the temperature does notdrop below -4 to -5C.

CultivationChusquea culeou, C. gigantea andC. andina are hardy throughoutthe UK and West Coast and MidAtlantic USA. The other speciesmentioned in this article will thrivein gardens with a maritime influence

but their tolerance of inland sitesis less well known. The factors thatmight limit them include summerheat with its attendant warm nightsand hot soil. All prefer a fertile,slightly acidic soil.

Another factor to consider is theultimate size of the plant in respectto garden space. A space of 3x3mwill allow for the expanse of foliagein relation to a smaller footprint

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PlantsmanThe

Chusquea foliosais a less hardy speciesthat has survived -4C in the US. Several ofthe more tender species have narrow leaves

Chusquea cumingiiforms a dense moundfrom which emerge long thin culms that archover if not supported by other vegetation


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on the ground. With heightstypically ranging from 3 to 6m, treatthem as a tall shrub in the overallgarden plan. The upright growingspecies can be planted as a specimen,a background shrub or as anunderstory plant to the tree line.They also make a good hedge alongboundaries and walls. The scandentspecies need vertical support toinhibit sprawling on the ground.

Because of the slow spread of the

rhizomes, chusqueas do not colonisenew territory in leaps and bounds.The new culms tend to directthemselves away from the centreof the plant in small steps rangingfrom 5 to 30cm. Over the yearsthe diameter of the clump expandsand may reach a larger size thanoriginally allotted.

Once established, wateringrequirements are minimal, however

additional moisture when neededand fertiliser will improve overallappearance. Being a grass, therecommended fertiliser mix shouldbe higher in nitrogen and lower inphosphorus and potassium, andapplied during the growing season.

New culms arising between springand autumn will take a year tomature and branch out their foliage.Older culms will gradually turn a

yellow green. If a clump is to bethinned, culms should be prunedout in the autumn. The culmsfrom several species make excellentgarden stakes, trellis or fencingmaterial. These should be trimmedand bundled to dry slowly.

PropagationThe best method of propagation isdivision in the growing season. Select

a portion of the plant that includesan older culm and new shoots justbreaking ground. Prune the olderculm down to 56 lower nodes,retaining the foliage. It isrecommended that this is doneseveral months head of digging. Ifthis pruning is not carried out, thedivision may defoliate from the lossof roots in transplanting. Using amattock, clear a circular trench

around the desired section. Thencarefully separate it from the mainclump using an extra strong spadecapable of sustaining hammer blowsor better yet a sliding-handled pistonspade. A strong tool is desirable asthe rhizomes and roots are verytough. Once the vertical sides arecut, it is necessary to undercut theclump under the rhizomes to detachthe remaining roots. Pry the clump

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GENUS PROFILE

Chusquea tomentosahas also survived -4C in the United States and has fine narrow leaves

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up with a digging bar using a blockof wood as a fulcrum. Try to keepthe root ball intact and damage tonew shoots at a minimum. Smallsingle rhizomes and culm divisionsare more likely to rot and die. Becareful not to over-water the newdivision or allow it to dry out.

Chusqueas can be propagatedfrom seed when it is available. Itshould be sown onto pots or trays of

sterile, mid-grade vermiculite, about67cm in depth, and just coveredwith a sprinkling to hide the seedsfrom view. These should be placedon a warm heat mat at 2224C.This usually has them germinatingin 21 days. Keep the medium moistand misted in partial light duringthis period. Transplant the seedlingsinto small containers after 34leaves appear. Take care to protect

them from birds and rodents.Bamboos flower after periods

ranging from 25 to 100 years andwill only do this at the end of a longlife. Generally, when a bambooflowers it is expected to die. Arecently imported clone ofC. culeouflowered only a few years agoresulting in thousands of seedlingsavailable for gardeners. This speciesis believed to have a 45-year life

cycle but less is known about theother species. However, sporadicflowering of different clones andgroups does occur at different times.

ConservationMany chusqueas are native to smallgeographical areas or restricted toisolated or specialist habitats. Ashuman activity encroaches uponand disturbs these habitats, often

in mountains, there is a danger tovulnerable species. An organisationdedicated to taking action for theconservation of native American

bamboos is Bambus de las Amricas(BOTA, www.bamboooftheamericas.org). The group assistsconservationists in Latin Americancountries in developing nationalcollections and training students tolearn more about the culture andutility of endangered bamboo species.

ConclusionChusqueas bring to the garden anexotic, evergreen foliage effect

unmatched by other plant species.They range in habit from a shrubbyvase shape to tall and erect or talland arching, or even scandent. Theleaves come in a number of coloursfrom blue-green to pine green.These large plants are easiest togrow in maritime-influencedclimates although they may requiremuscular maintenance from timeto time in cramped locations.

GIB COOPER operates Tradewinds /Bamboo Direct Nursery in Oregon,USA. Website: bamboodirect.com

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PlantsmanThe

Crompton, D (2006)Ornamental Bamboos.Timber Press, Portland, OregonDemoly, JP (1999) Une especenouvelle pour le genre ChusqueaKunth.Bambou 30: 810

Judziewicz, EJ, Clark, LG,Londoo, X, & Stern, MJ (1999)

American Bamboos. SmithsonianInstitution Press, WashingtonMeredith, TJ (2001)

Bamboo for Gardens.Timber Press, Portland, OregonTriplett, J & Clark, L (2003)Ambiguity and an American bamboo:theChusquea culeou species complex.

Bamboo Science and Culture 17: 2127Whittaker, P (2005)Hardy Bamboos:Taming the Dragon. Timber Press,Portland, Oregon

REFERENCES & BIBLIOGRAPHY

Chusquea valdiviensisis one of the most vigorous species, sending out long climbing culms into trees

chusquea - mountain bamboo of latin america

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