The Length of the Life Cycle of a Climbing Bamboo. A Striking Case of Sexual Periodicity in Chusquea abietifolia Griseb. Author(s): William Seifriz Source: American Journal of Botany, Vol. 7, No. 3 (Mar., 1920), pp. 83-94 Published by: Botanical Society of America Stable URL: http://www.jstor.org/stable/2435166 Accessed: 03-08-2014 23:09 UTC

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This content downloaded from 130.92.9.57 on Sun, 03 Aug 2014 23:09:33 UTC All use subject to JSTOR Terms and Conditions AMERICAN JOURNAL OF BOTANY VOL. VII MARCH, I920 No. 3

THE LENGTH OF THE LIFE CYCLE OF A CLIMBING BAMBOO. A STRIKING CASE OF SEXUAL PERIODICITY IN CHUSQUEA ABIETIFOLIA GRISEB.*

WILLIAM SEIFRIZ

Certain plants are known to live vegetatively for many years, then flowerand die. The most frequentlycited example of this phenomenonis that of the centuryplant, Agave americana,which lives fora periodof years withoutflowering, then sends up a tall, prominentinflorescence, and finally, after the maturingof the seeds, dies. This sexual periodicityis also char- acteristicof certainbamboos which blossom only aftera cycle of years and then all simultaneouslythroughout an extensiveregion. The bamboos in the South Brazilian provincesof Santa Catharina and Rio Grande do Sul are said to blossom at intervals of about thirteenyears, and Bambusa arundinacea on the west coast of CisgangeticIndia blossomsat intervalsof about thirty-twoyears (i). The complete and simultaneousdying offof the bamboos may in some communitiesprove disastrousby the wipingout of the chiefavailable source of buildingmaterial through the transformation of luxuriant bamboo forestsinto barren areas; or, it may prove of great economicvalue as a source of grain,especially when it comes,as it is said to (2), in times of droughtand consequentfamine. The lengthof the intervalof years varies greatlyin differentbamboos. Bean (3) reportsthat "Bambusa tesselatahas been in cultivationfor prob- ably over sixty years, yet I have seen no record of its having flowered anywhere." In strikingcontrast with this is the case of Arundinar'ia falcata var. glomeratawhich flowersalmost every year on a certainnumber of culms. The latter is a case of partial or sporadic floweringas contrasted with the completeand simultaneousflowering which is the rule among bam- boos. Intermediate types also exist. Bean (3) mentions the case of A rundinariaSimoni which floweredon odd culms in the bamboo garden at Kew forseveral years. He says, "excepting that the floweringculms died, the plants were in no way affected.. . . They continued to flowerin this way every year up to 1903, by which time we had almost come to regard A. Simoni as a perenQial. In that year, however, the plants floweredon every culm, and, after producingan abundance of seed, died. Afterthat * BotanicalContribution from the JohnsHopkins University No. 62. [The Journalfor February (7: 45-82) was issued March IO, 1920.] 83

This content downloaded from 130.92.9.57 on Sun, 03 Aug 2014 23:09:33 UTC All use subject to JSTOR Terms and Conditions 84 WILLIAM SEIFRIZ not a single trace of leaf growthwas ever visible and the plants were ulti- mately uprooted" This peculiar periodicityin the life of bamboos was strikinglybrought to my attentionduring a recentstay in Jamaica. On my firstwalk along the trail which runs fromCinchona to Morce's Gap in the Blue Mountains, my attention was called, by Dr. Duncan S. Johnson,to the many dead patches of the climbing bamboo, Chusquea abietifolia. Dr. Johnson re-

FIG. I. Anentanglement ofdead Chusquea abietifolia. marked that on threeprevious visits to Cinchona he had always found the Chusquea in full foliage, forminglarge entanglementswhich, like the tree ferns,stood out as a prominentfeature of the tropical vegetation. The Chusquea was still there,interwoven into mats beside the mountain path or hanging in festoonsabove the trail, but the color was no longer green,for every plant seen on that firstwalk was dead. It was immediately suspected that this climbingbamboo had, true to the habits of its tribe, died as a result of profuseflowering following a long period of sexual inac- tivity. It seemed, therefore,advisable to collectall obtainable data bearing upon the life historyof this Chusquea. These data here published will bring up to date the storyof the lifeof the Jamaican Chusquea which was begun by Sir Joseph Hooker and Sir Daniel Morris thirty-threeyears ago. The presentobservations seem to fixthe lengthof the lifecycle.

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The climbingbamboo, Chusquea abietifolia,is, in reality, a scrambler with no specialized climbingorgans-although one's firstencounter with the plant is likely to suggest the presence of vicious thorns,for the leaf midribterminates in a verysharp, protrudingpoint. The long,erect young shoots push upward among the surroundingplants and are held fromslip- ping back by the subsequent developmentof whorls of leaves and lateral branches. The height attained seldom exceeds 30 feet,while the mats of interwovenstems are often IO to I5 feet across. If high supports are lacking Chusquea succeeds very well in climbing over low shrubs. The maximum basal diameter of the old culms is hardly a quarter of an inch, in contrastto the 5- and 6-inch culms of the closely related Bambos (Bam- busa) vulgarisof the Jamaican lowlands. Chusquea abietifoliais little known outside of Jamaica. It has been reported (4) from only two other localities, both in the West Indies-

FIG. 2. Growingseedlings of Chusquea abietifolia.

Porto Rico (Monte Alegrillo) and Haiti (Monte Furcy). In Jamaica this rare bamboo is confinedto the mountainousinterior of the island. It does not occur much below 4,000 feet and is most abundant on the mountain ridges,being found on the very summitof Blue Mountain Peak, 7,360 feet above sea level. The habitat of the plant is apparently not so definitelydependent on moisture as it is on altitude, although the lower limit of 4,000 feet is

This content downloaded from 130.92.9.57 on Sun, 03 Aug 2014 23:09:33 UTC All use subject to JSTOR Terms and Conditions 86 WILLIAM SEIFRIZ possibly fixedby moisturerequirements. Rainfall in the higheraltitudes of these tropical mountainsis always ample for vegetation,yet there is a pronounced differencein the soil moisture of exposed ridges and shaded ravines. Chusquea is found in both these regions; on the sunny,hot, dry spurs where vegetation is relatively sparse, and in the dark, cool, wet gulches where tree fernsand other moisture-lovingplants abound. Chus- quea is, however, most abundant under conditions intermediatebetween these two. Published descriptionsof this climbingbamboo are few and brief,that of Grisebach,in his Flora of theBritish West Indies, beingamong the earliest. A more complete systematicaccount by J. D. Hooker appears in the Bo- tanical Magazine (Curtis) for I885. The firstdefinite reference to sexual periodicityin Chusquea appears in a shortnotice by Morrisin the Gardener's Chroniclefor I886. He writes, "The floweringof this plant appears to take place, as in most Bambuseae, at long intervals." The data pertainingto the life habits of Chusquea abietifoliapublished here were obtained from the followingsources: first,from Wm. Harris, governmentbotanist of Jamaica, to whom I am greatlyindebted formany kindnessesduring my stay on the island: second, fromseveral published articles herein referredto, which were kindly broughtto my attentionby Assistant DirectorArthur W. Hill, of the Royal Botanic Gardens at Kew: third,from the notes of Daniel Morrisand J. H. Hart recordedin a copy of Grisebachin the libraryof Hope Gardens,Jamaica: fourth,from the natives living in the mountains,especially David Watt, whose long experiencein collectingfor Jamaican and visitingbotanists has made him uncommonly familiarwith the plants of the mountain forests:and lastly, frommy own observationscovering a period of six weeks and extendingover a ten-mile stretchof the Blue Mountain Range. During June, I9I9, nearly all mature plants of Chusquea abietifoliain the Blue Mountains of Jamaica were dead. On the otherhand, the ground in many places was coveredwith seedlings varying from an inch to i8 inches in length. Diligent search brought to light only a few patches of old, living plants. Still fewerspecimens were foundbearing fruit. The firstquestion which naturally arose was, when did this climbing bamboo last flower? I was informedthat there had just ended a most profuseflowering of all plants in the mountains whereverseen, and that the time of floweringextended over morethan a year. The question which next presented itselfwas, how long a time had elapsed between this and -thelast previous flowering? Definiteinformation on this point was ob- -tainedfrom Mr. Harris, who writes,"Chusquea floweredgenerally in the Blue Mountain regionsin I885-6 and died down everywhere." This first -recordedflowering period also extendedover morethan a year, as is evident fromthe note of Hart supplementingthat of Morris. The latter states -thatChusquea was firstnoticed in flowerin the fall of I884, and that in

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I885 it floweredgenerally. Hart adds, "It floweredalso in I886 or rather continued floweringfrom i885." That the outcome of the recent floweringof Chusquea-the death of all mature plants and their replacement by innumerable seedlings-is identicalwith that followingthe last generalflowering 33 yearsago, is evident

......

FIG. 3. Anold basal cuim of Chusqueaabietifolia with a long,young, leafless shoot. fromthe writingsof the early observers. Morris (5) tells the story in this manner: The Chusquea "began to shed its leaves and to assume a dull, rustycolor.... When the seed was set the stem began to die down,and apparentlyevery plant in the island died, root and all. At the presenttime (I886) the ground in the forestswhere the Chusquea grew is covered with millionsof seedlings,and in due time these will take the place of the former generation. In 1884 some plants of Chusquea were sent in a Wardian case to the Royal Botanic Gardens at Kew. Hooker, referringto the Kew plants, wrote: "In December last (1884) they suddenly burst into flowercausing me to fearthat, afterthe mannerof so many species of this most remarkable tribe of grasses to which they belong,they may not survive the flowering

This content downloaded from 130.92.9.57 on Sun, 03 Aug 2014 23:09:33 UTC All use subject to JSTOR Terms and Conditions 88 WILLIAM SEIFRIZ period." The Kew plants died just as did the wild ones. It is worthyof special note that the Kew plants, after being transplantedto an entirely new and differentenvironment, flowered simultaneously with the wild plants in Jamaica. It is, therefore,immediately apparent that Chusquea ab'ietifoliahad just ended (in I9I8) a life cycle of about thirty-threeyears duringwhich time it had grown vegetativelyonly, until the last year when it flowered, disseminatedits seeds, and died. There are but three other species of climbingbamboo, all belongingto the genus Arthrostylidium.These also, like the Jamaican Chusquea, are foundonly in the West Indies. It is veryprobable that at least one of these other species goes througha cycle similar to that of Chusquea abietifolia. Arthrostylidiumsarmentosum has been collectedin floweronly once (6). Many days of trampingover the mountaintrails near Cinchona revealed but a singlegreen specimen of Chusquea, the only livingplant among many hundredsof dead ones borderingthe trail in the two-milewalk fromCin- chona to Morce's Gap. Whether the presence of this sole living mature plant among so many dead ones is due to certainedaphic conditionswhich have delayed floweringand thus possibly produced a plant of altered life cycle,is uncertain. Its possibilitywill be discussed in detail later. The ascent of Blue Mountain Peak showed a similarstate of affairsto exist in that locality. The trail to the summitwas lined with innumerable patches of dead bamboo. Several green plants were found but these few were not freshand thrivingin appearance, being apparently in a dying condition. Some days later I learned of greenplants growingon an exposed, rocky spur. Investigation firstrevealed short, fresh,green tufts of Chusquea, which proved to be young shoots fromold rootstocks. This region had recently been burnt over. The charred stubble was still evident. The presence of green Chusquea here seemed easily explainable: the parent plantshad been burntto the groundbefore their life cycle was complete,and the living rootstockshad sent up new shoots which were continuingthe growthof the plants and thus carryingon the vegetativeportion of the life cycle beyond the normal limit. Opposed to this suppositionis the state- ment of Hackel (7) that small plants fromcuttings or layers of bamboos blossom at the same time as do the parents fromwhich they were taken. It would be very interestingto determineexperimentally just how such a catastropheas the destructionof that part of the plantsabove groundshortly beforetheir time of floweringwould affectthe normallife history of a plant like Chusquea. Continuing along the spur above mentioned,I subsequently found a fair-sizedarea with numerousold but green and thrivingplants. They were not in flowerbut were healthy,actively growingspecimens, sending out an abundance of long, young shoots. Here was a prominentexception

This content downloaded from 130.92.9.57 on Sun, 03 Aug 2014 23:09:33 UTC All use subject to JSTOR Terms and Conditions LENGTH OF THE LIFE CYCLE OF A CLIMBING BAMBOO 89 to the generalcondition existing throughout the mountains. A noteworthy featureof the exception,however, was the fact that these healthy,green plants were all in a single and comparativelysmall area. The possibility of explainingtheir persistence by some externalcause is, therefore,greater than would be the case had several distinctscattered groups been found. The regionin which these living plants are growingis one experiencing the extremeof mountainaridity above 4,000 feet. The ridgeis hot and dry,

FIG. 4. Seedlings of Chusquea abietifolia. and covered with vegetation characteristicallyxerophytic (Pteris aquilina, Gleichenia Mathewsii, A gave americana). Morce's Gap trail and Blue Mountain Peak, on the otherhand, whereChusquea is, with fewexceptions, to be f'oundonly as old, dead plants and young seedlings,are moistregions characterized by hygrophilousplants. Immediately below the dry area where the patch of living bamboos exists, there is a moist, shaded gulch where no living,mature Chusquea was found; forhere, in an environmnent like that at Morce's Gap and on Blue Mountain Peak, the old bamboos are dead and seedlings are abundant. Here also flourishesa hygrophilous floraof tree fernsand succulent herbs. It seems, therefore,reasonable to conclude that the climbingbamboo has in thismore arid regionin some man- ner assumed an altered life cycle. The single green specimen, already referredto, foundnear Morce's Gap was growingon the hot and dry south- west slope of the mountain, a spot differingmarkedly fromthe nearby, shaded, semi-moistregions along the trailwhere Chusquea was represented by an abundance of dead plants and of livingseedlings.

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One ratherwelcomes an exception to the strikingregularity in sexual periodicityof a species extendingover a large territory. Indeed, one would expect not a singleexception but many,brought about by differentrates in seed germination,and in growthboth of seedlingsand mature plants due to differencesin environmentalfactors such as moisture,light, temperature, and soil, whichwould ultimatelygive rise to plants whose time of flowering would precedeor followthat of the majority,and whichwould thus,in time, produce many plantswhose life cycles overlapped so that some out of the many could be foundin flowerin any year. It would be exceedinglyinter- esting to attempt to bring about such a state artificiallyby deferringthe sowing of the seed, and thus attemptingto postpone the time of flowering or to shortenthe life cycle. It would seem, however,that this experiment must have been many timesperformed by nature (i.e., if the seed is capable of germinatingafter I or moreyears) so that we should be able to judge from the present condition of the wild plants of Chusquea whetherthe cycle can be alteredin thisway. Bean (3) is of the opinionthat the simultaneous floweringof bamboos followssome general law. What this general law mightbe he does not suggest. Yet he does believe that under cultivation the systemof simultaneousflowering of some of these species would appear to be breakingdown, and he cites the case of Arundinaria Falconeriwhich floweredin England, in the vast majorityof cases, in I876, but the flowering of the generationat the time he wrote (I907) had already extended over fiveseasons. That a breakingdown of simultaneousflowering in Chusquea abietifoliais taking place in the wild state is suggestedby the exceptions that I have noted and by the fact that this climbingbamboo was detected in flowerin I9II and was also floweringfreely at the base of Catherine's Peak, but not elsewhere,in November,1912. In fact,Mr. Harris suggests, "It is just possible that individual plants of Chusquea may be found in flowerin any year if carefulsearch were made forthem." In spite of these several exceptions,it remainsa strikingfact that fully 98 percentof all plants of Chusquea abietifoliafound in Jamaica in a region some ten miles in length,varying from 4,000 to 7,000 feet in altitude, and showingconsiderable diversitiesof light,temperature, and moisture,have floweredand died in a single briefperiod not exceedingtwo years, aftera purelyvegetative growth of more than thirty-oneyears. This completecycle of thirty-threeyears differsby only one year from that given by Brandis (8) for Bambusa arundinacea in India. It seems quite possible that the lifecycles of these two genera are the same, forthe exact time of floweringis not always readily determined. The general floweringof a species in one particular year may be heralded by a few forerunnersthe previous year and followedby that of laggards the next. Morris states that the last previous floweringof Chusquea in the Blue Mountains ofJamaica commencedin I884, and Hart reportsit as continuing until I886. The exact time of the recentflowering is not definitelyknown.

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David Watt is of the opinionthat he firstsaw Chusquea in flowerin the fall of I917. I myselfcollected a few fruitingbranches in the early summerof I919. The climbingbamboo was, therefore,probably at the heightof its floweringperiod in I885 and in I9I8, making the cycle one of thirty-three years. I have referredto the possible effectof environmenton change in time of flowering. Equally interesting,and possibly as difficultof solution,is

FIG. 5. Fruits of Chusquea abietifolia. Collector, William Harris. the ultimate cause of the simultaneousflowering of nearly all plants in a certain locality. The obvious suggestion,often made in such cases, that this peculiarityis innate,does not, of course,solve the problem. It simply indicates that we must seek our explanation in causes operative beforethe initiationof the individual. Attemptsto associate the sexual periodicityof plants with seasonal or

This content downloaded from 130.92.9.57 on Sun, 03 Aug 2014 23:09:33 UTC All use subject to JSTOR Terms and Conditions 92 WILLIAM SEIFRIZ other environmental changes may seem as far-fetchedas to ascribe to climate or food the periodicappearance of the seventeen-yearlocust which has this year (I919) infestedcertain regions of our country. It is however, quite possible that the durationof the lifecycle of plants exhibitingsexuaal periodicityis the direct result of certain known, presentor past, stimuli. An apparently very clear example of such an association between season and periodicityis seen in the life cycle of annuals which flowerand die at definiteseasons of the year. But one can not always be certain that the most evident and seeminglycontrolling factor in such a case is the one at presentactive. A native annual in the temperatezone commonlyrests in winter, germinatesin the spring, fruitsin summer,and dies in the fall. This sequence of events one is likely to attributeto the sequence of the seasons. Yet most annuals ifgrown in a greenhousewhere seasonal changes are non-existent(except as to light) can, by sowing of seeds at the proper time, be made to fruitin any chosen monthof the year withoutregard to seasonal conditionsout of doors. Thus are the successive steps, fromger- mination to death, in the life span of an annual grown in a greenhouse accurately maintainedwithout evident relationto any externalcontrolling factor. That is, the annual germinates,fruits, and dies in the same interval of time that it always has required,and does this in an environmentquite differentfrom the seasonally progressiveone of its natural habitat. This behavior seems clearly to belie the validity of the assumption that the presentseasonal rounddetermines the durationof each phase of the develop- mental cycle,and thus of the cycle as a whole. There are reported,however, examples of the floweringof plants being regularlybrought on by such externalfactors as moisture. The followingis such an example cited by Morris (5): "A prolongeddrought in India is often accompanied by the floweringof the common bamboo, and on this account the natives associate the two phenomena in a manner which is emphasizedby the factthat the bamboo grainduring seasons of droughthas provided them with the only available means of support." Accordingto Ridley (cited by Schimper, I) two species of Hopea and four species of Shorea blossom with great regularityevery sixth year. These cycles are said to coincidewith dry years. Morris (5) believes that the long intervals at which the floweringof Chusquea takes place probablydepend " fortheir exact lengthupon the aspect of the prevailingseasons." Weather reports from Cinchona show, during the years precedingthe recent floweringof Chusquea, no pronounced digression in temperature from the general average. The rainfall was unusually heavy for two years immediately precedingthe floweringof Chusquea. It is hardlylikely, though possible, that an over-abundanceof rain should bringon a floweringperiod in Chus- quea in Jamaica and droughtbe the cause of floweringof anotherbamboo in India. Furtherproof against the theorythat time of floweringis determinedby

This content downloaded from 130.92.9.57 on Sun, 03 Aug 2014 23:09:33 UTC All use subject to JSTOR Terms and Conditions LENGTH OF THE LIFE CYCLE OF A CLIMBING BAMBOO 93 presentseasonal factorsis to be had fromthe behavior of the climbingbam- boos sent to Kew. Morris (5) himselfpresents a bit of evidence against his own contentionwhen he says, " Both the wild plants at Jamaica and the cultivatedplants at Kew (althoughthe latterwere undersuch verydifferent conditions)were in flowerat the same time." Should the life cycle of Chusqueeaabietifolia prove not to vary fromthe thirty-threeyears which it has been found to be-just as the cycle of Bambusa arundinacea has, fromthree successive observations (I804, I836, i868) been found to be exactly thirty-twoyears (i)-then it would seem hardlylikely that the lengthof thisterm of years could be definitelyascribed to present climatic influences,unless there is some larger climatic round of years, such as that suggestedby Bruckner(9). It is interestingto note, though of how much significancethis may be is pure conjecture,that the climatic oscillation ascertained by Bruckner (9) closelyapproaches in lengthof years the lifecycle of Chusquea. There is, however,in addition to Bruckner's35-year alternationof wet and dry epochs, a supposed variation of rainfallin a cycle of eleven years, coinci- dentlywith the sunspotcycle (io). It is as yet by no means well established that climaticchanges are periodic,and thereis but littleto supportthe idea that droughtsoccur rhythmically,especially with any great precision. In consideringthe possible relationshipbetween sexual periodicityin plants and climatic oscillations I have had in mind-as I assume others have had in their attempts to associate the two-only present climatic influences. That past rhythmicalvariations in rainfallor in temperature have, throughthe ages, fixed the life-cycleof Chusquea is quite possible. So strikingis the association between the lifeof an annual and the seasons that it seems very probable indeed that the cycle of annuals is the direct result of seasonal influences,and that this cycle has, throughmany gener- ations, become so firmlyestablished as to be unalterablethrough the tem- poraryelimination of seasons by transferringthe annual to a greenhouse. This problem can, however,and should, be attacked fromother view- points than the purely ecological one. Other factors than such external stimulias droughtsand similarseasonal epochs may have been at work in establishing,or still are at work in maintaining,sexual periodicityin Chus- quea. The problem may be of the same nature as that of puberty and senilityin organisms. We know, for example, that certain organismsre- quire a certainnumber of years in which to reach sexual maturity,and we know that certain organismslive about so long and never exceed a certain maximum. The presentcauses of such phenomenaare not as yet seriously thoughtto be environmentalin nature. That they may be somewhat in- fluencedby environmentis possible. Lack of food,for example, is said to hasten the attainingof sexual maturityin man, but the digressionfrom the mean is slight and has no direct bearing on the original establishmentof the phenomenon.

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In one respect,however, the periodicityof Chusquea differsstrikingly from-the cycle of annuals and the aging of organisms. That the span of life of an individual Chusquea is thirty-threeyears is no more remarkable and is as satisfactorilyexplainable as is the fact that an annual lives one year, man eighty years, and a Sequoia 5,ooo years. But an hypothesis which will explain these phenomena is not necessarilysufficient to account for the simultaneousflowering of fully98 percent of the individuals of a species extendingover a great stretchof country. There is as yet, it seems to me, no adequate explanationof the behavior of Chusquea. That seasonal factorsat presentactive bringon this simul- taneous floweringis very unlikely. That past climatic influencesare responsibleis quite possible. But the ultimate cause I should be inclined to search for in the physical and chemical make-upof itsprotoplasm; fully realizing, however, the possibility,indeed the probability,that this very nature of the protoplasmhas come to be what it is in part because of its past environmentas well as because of its own originalconstitution. BOTANIcAL LABORATORY, JOHNS HOPKINS UNIVERSITY

BIBLIOGRAPHY i. Schimper,A. F. W. Plant geography. Oxford,I913. 2. Munro,Col. Monographof the Bambusaceae. Trans. LinneanSoc. London,26: i- 157. i868. 3. Bean, W. J. The floweringof cultivatedbamboos. Kew Bulletin1907: 228-233. 4. Hitchcock,A. S., and Chase, Agnes. Grassesof the West Indies. Contrib.U. S. Nat. Herb. i8: 261-47I. I917. 5. Morris,D. Chusqueaabietifolia. Gardener'sChronicle 20: 524. i886. 6. Chase,Agnes. Noteson theclimbing bamboos of Porto Rico. Bot. Gaz. 58: 277-279. I914. 7. Hackel,E. Gramineae. Englerand Prantl,Nattirlichen Pflanzenfamilien. II, 2: 90. 8. Brandis,D. Bambuseae. Englerand Prantl,Natiurlichen Pflanzenfamilien. II, 2: 90. 9. Bruckner,E. Klimaschwankungen.Vienna, I890. io. Hann, J. Climatology. Eng. trans.by R. DeC. Ward. New York,I903.

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