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BOTANICAL GAZETTE
I82
3. BROWNE,
ISABEL.
A new theoryof the morphology of the Calamariancone. Ann. Bot. 4I :30I320,
[DECEMBER
Sphenophyllales?Amer.Jour.Bot. 35:
350-358.
I 948-
FREDDA. Notes on some plant remains
from the Carboniferousof Illinois. BOT.GAZ.
I I. REED,
I927.
4. DARRAH,
W. C. A remarkablefossil Selaginella
with preservedgametophyte.Bot. Mus. Leaflets, HarvardUniv. 6: I I3-I36. I938.
5. FLORIN,
R. On the structureof the pollen-grains
in the Cordaitales.SvenskBot. Tidskr.30:624-
I00
I2.
I3.
65 I . I936.
6. HIRMER,M. Handbuch der Paleobotanik.
Munchen,Berlin. I927.
7. HOSKINS,
J. H., and CROSS,
A. T. Monographof
the Paleozoiccone genus Bowmanites(Sphenophyllales). Amer.Midl. Nat. 30:II3-I63.
I943.
8. gEFFREY,
E. C. The development,structureand
affinitiesof the genus Equisetum.Boston Soc.
Nat. Hist. Mem. 5: I55-I90. I889.
9. LACEY,
W. S. The sporangiophoreof Calamostachys.New Phytol. 42: I-4. I943.
I 0. LEVITTAN,
E. D., and BARGHOORN,
E. S.
Sphenostrobus
Thompsonfi:A new genus of the
I4.
324-335.
I938.
SCOTT,
D. H. Studiesin Fossil Botany. Adam&
CharlesBlack, London.I909.
SELLING, O. H. Studies on Calamitean cone
compressions by means of serial sections.
SvenskBot. Tidskr.38: 295-330.
I944.
STEVENS, N. E. A palm from the Upper Cretaceousof New Jersey.Amer.Jour.Sci. 34:42I436.
I9I2,
N. Phloemhistologyin stigmarian
appendages.Trans. Ill. Acad. Sci. 33 :54-57.
I5.
STEWART, W.
I6.
WALTON,
I 940.
Fossil
J. An Introductionto the Study of
Plants. Adam & CharlesBlack, London.
I 940.
I7.
. On some Lower Carboniferous
Equisetineae from the Clyde area. Trans. Roy. SOC.
(Edinburgh)6I:729-732.
I949.
A COMPARISONOF SEASONOF CAMBIALGROWTHIN DIFFERENT
GEOGRAPEICRACESOF PINUS PONDEROSA
R. F. DAUBENMIRE
Introduction
Ecotypic specialization in different
parts of the ranges of widely distributed
species is a phenomenon that has commanded the attention of botanists for
several decades. Experience has usually
shown that when plants are moved from
their native habitat into a differentenvironment they become subject to injuries
from factors associated with the new environment, although occasionally they
may prove more successful. The slow
genetic fitting of plant populationsto the
peculiaritiesof the area which they have
occupiedfor a long time is especiallyimportant in the artificialestablishmentof
forests, for usually there are availablefor
use in plantations seed lots representing
the same species but from populations
attuned to widely different environments. The long life-cycle of the tree
makes it possible to invest much time
andmoneyin reforestation
beforegenetic
weaknessbecomesapparent;moreover,
the unsuccessful
plantingmay be expensive to remove,and by crosspollination
it may seriouslycontaminatenear-by
nativetrees.In recognitionof this problem the UnitedStatesForestServiceestablishedan experimentalplantationof
Pinus ponderosa
Laws.in northernIdaho, with the purposeof determiningthe
relative value of seeds from different
parts of its areafor use in reforestation
in northernIdaho.
BetweenI9II and I9I7 seedsor seedlings from twenty-two localities were
plantedin contiguousplots at the Priest
River ExperimentalForest in Bonner
County,Idaho.The habitatis an upper
river terracemantledwith sandy loam.
Climateandsoil in this regionpermitP.
ponderosa
to growwellunderopenconditions,but the environment
is too coolfor
Ig50]
DAUBENMIRE GEOGRAPHICRACES OF PINUS
satisfactorynaturalgerminationor satisfactory growth after the forest approaches maturity. This choice of location for the experimenthas considerable
bearingupon the practical applicationof
the findingsIbut is of little consequence
from the purely scientificstandpoint;for,
although the climate here may generally
be unsuited for the commercialplanting
of this species, it is at least conducive to
the growth of the trees in young plantations and therefore may be considered
adequatefor a comparativetest of racial
diSerences under uniform environment.
Twenty-two to 26years after the seeds
germinatedthe results were describedby
WEIDMAN
(6). His report described the
origin of the populations, climates of
those regions,arrangementof the plantation, native vegetation and soils, and the
following attributes of the populations:
numberof needles in the fascicle, length
and persistence of needles, anatomy of
needles, general appearance of foliage,
and heights and diameters at ages of 22
or 23 years. In summarizingall the observations,WEIDMAN
tentativelygrouped
the populations into four geographic
races.
Someof the populationsplanted at the
Priest River Experimental Forest have
suffered very high mortality, and one
(Shasta) was completely exterminated
by a sudden drop of temperaturefrom 7°
to-25° C. within 20hours in December,
I924. Appraisalof injury that may be attributed specificallyto this sudden drop
in temperatureshowedthat the Siskiyou,
Santa Fe, and Coconino races also suffered heavily, although devastation was
not completeas with the Shasta race (4).
I Anotherstudy of ten populationsof P. ponderosa fromdifferentregions,in whicheach population
was distributedamongsix widely differenthabitats,
showedthat relative rates of height growthcannot
be predictedfor one habitaton the basis of comparisons madeon another(5).
I83
The hypothesis has been advanced that
trees suffer from autumnal frost as a result of continuing some phase of growth
activity too late in the season (3, 7), and
WEIDMAN
suggestedthis as a possibleexplanation for heavy mortality in some
races: "Presumably the long period of
growth activity characteristic of...
Siskiyou progeny, has been one of the
causes of the frost damage suffered by
the latter in northern Idaho" (6:879).
One of the objects of the present study
was to determineif the races experiencing high mortality terminate radial
growth of their stems relatively late in
the season.
Studies by the writer of a number of
species of trees growing some I77 km.
(I IO miles) south of the Priest River Experimental Forest indicated that daylength exerts a marked control over
the date of commencement of cambial
growthin some species,althoughthis was
not true of the specimensof P. ponderosa
of unknown and possibly different geographic origin which were included in
that study (2). It was evident that the
collectionof racesof knownoriginsat the
Priest River ExperimentalForest representing nearly I4° of latitude could provide conclusiveinformationon this problem, and, consequently, this question
representsa second object of the present
study.
Since WEIDMAN'S
report did not include recordsof the season of cambialactivity, permissionwas requestedto study
the trees from this standpoint. The writer is gratefulto the United States Forest
Service for making the experimental
plots availableand for assistancein reading dendrometerswhich the writer installed. Further support was given the
project by funds provided for biological
and medical research by the State of
Washington Initiative Measure N. I7I,
I84
BOTANICALGAZETTE
Figure I shows the total geographic
area of P. ponderosa (incl. var. SCOpU/Orurn Engelm. which the southernmost
stations, at least, represent) and the
points of originof the populationsselected for the presentstudy. The populations
are referredto lby name of the National
Forests in which they were collected.
[DECEMBER
Methods
Dial-gauge dendrometersof a type (I)
which the writerhas comparedwith similar instruments and found eminently
more successfulwere used in this investigation. Instrumentswere installed in the
autumn of I947 and recordsmaintained
throughout I948. During the period
FIG. I.
Originsof populationsconsideredin this study, as related to total range of Pinus ponderosa,
includingvar. scopulorum.
I
950]
DAUBENMIRE GEOGRAPHICRACES OF PI)JUS
I85
when growth was expected to begin, the main question which prompted the
readingsweremadeat intervalsof usual- study can be answered with reasonable
ly less than I week,but at otherseasons assurance of accuracy. The conclusions
longerperiodselapsedbetweenobserva- which may be drawn from the data reptions, dependinguponthe state of cam- resented by figure 2 are as follows.
bial activity.
Nearly all populations began growth
Formost treesof temperatelatitudes, after mid-May and completedgrowth in
day-to-daydiameterincreaseis a regular late August. Median dates for the 5%ox
phenomenon
onlyduringthe mainperiod 50%on
and 95%olevels were May 23, June
of growth.Duringthe dormantseason 2I, and August 22. The Coconinopoputrunks commonly exhibit periods of lation was an exception in that its camshrinkagewhichare associatedwith se- bial growth began about 2 weeks later2
ries of dry days in the latter half of the than the averagefor all groups.The midsummer,or subfreezingweatherin win- point in its growth was proportionately
ter. They may also swellintermittently. late as well. The Harney population,repIt is consequentlyvery difiicultto estab- resented by only two trecs, also began
lish a precisedate for the beginningand growth distinctly later than average for
end of growth,but the date for comple- all groups. Here, however, the rate of
tionof 5%oand95So of the season'sincre- growth was exceptionally rapid once the
mentmaybe approximated
by interpola- cambiumbecame active, so that its midtion, with verylittle probabilityof error point was not delayed and, in fact, was
owing to the smoothnessof the curve reached earlier than in certain of the
oncethe cambiumbecomesactive.Radii other groups.
as measuredon December3o, I947, and
The Helena, Bitterroot 2 200 m. (7200
on NovemberI 2, I948, seemedleast af- ft.), and possibly Ashley populations all
fectedby frostshrinkage,andthe differ- terminated their growth a little in adencesbetweenthese readingswereused vance of the others, although they had
in calculatinggrowth on a percentage not begun to grow earlierin spring than
basis.
most of the others. Except for one tree,
Resultsand discussion
the growingseason of the CoconinopopA strikingfeatureof the resultswas ulation was shorterthan average as a rethe variationexhibitedby differenttrees sult of postponement of inception in
fromthe samepoint of origin.In other spring, whereasthe Helena, Ashley, and
studiesby the writerthreevigoroustrees Bitterroot 2200 m. racesexhibitedslightselectedto representa populationhave ly shortened growing seasons owing to
alwaysshowedreasonablyclosesimilari- earlier cessation of growth in late sumty in behavior,but at the Experimental mer.
Forest there was so much divergence The Bitterroot populations representamongindividualswhichaverageswould ing differentaltitudes (I 200 [4000ft.] and
obscurethat, in presentingthe results, 2200 m.) differed only in that the race
the dataforeachtree arekept separate. from the higher altitude ceased growing
It is obviousthat statisticalsignificance earlier.In view of this evidence of racial
cannotbe claimedfor any of the resultss differentiationin P. pondeYosa
according
but sincethey, for the mostpart, reveal
Lateness also characterizesthe beginning of
little differences
amongthe populations, apicalgrowthin this population(6).
2
s
BOTANICALGAZETTE
to
I86altitude, all results from the comparative plantation may be strongly conditioned by the elevation from which the
populations originated. However, the
physical data of altitude that are available (6) cannot be interpretedclosely because the character of biologic environment in mountains depends upon the direetionof slope exposureas much as upon
elevation above the seas. The environment of the plantation at the Priest River ExperimentalForest is close to the upper zonal (not altitudinal) limits of P.
porderoscrin the Southern Selkirks,
whereasthe originalhabitats of the popX
l
[:DECEMBER
ulations may have been from the upper,
middle, or lower parts of the total elevational ranges in the other mountain systems. Therefore, the change in zonal
status in some cases may have reduced
and in others augmented the temperature difference involved in latitudinal
displacement.
WEIDMAN
(6) suspected that the
heavy mortality sufferedby the Siskiyou
population subsequentto planting might
have resulted from too late an extension
of the growingseason in the autumn, for
this population originated from a very
mild climate. The present study, how-
|
X
,'
'
COLVILLE
.
l
HELENA
I
l I
I
l
BITTERROOT
2200
|
l
l
,
M
I
X
BITTERROOT1200
X
l
l
l
M
R
UMATILLA
l
CUSTER
,1
1
1
l
l
l
l
l
l
.
HARNEY
E
{
l
w
{
SISKIYOU
|
s
l
l
BOISE
l
l
ASHLEY
t
2
:
sl
l
l
l
l
'
'
r
ROOSEVELT
-
-
s
SAN ISABEL
SANTAFE
X
.
.
l I
l
a
io
MAY
,
E
l
|
,' |
lo
20
JUN
1
10 20
JUL
1
.
s
'
4
lo
,
X
10 20
AUG
1
COCONI
NO
|
10 20
SEP
1
'
10 20
OCT
FIG. 2.
Principalperiodof cambialactivity of each tree studied,based on periodstartingwhen 5%0°f
total annualincrementwas recordedand endingwhen incrementwas 95% completed.
Ig50]
GEOGRAPHICRACES OF PINUS
DAUBENMIRE
I87
the growthpatternof the species
from
doesnot substantiatethis hypotheever,
a wholeexhibitno geographictrends.
as
Amongthe Siskiyou,Bitterroothigh
sis.
eitherdoesnot determinethe
Daylength
SantaFe, and Coconinopopualtitude,
of cambialactivity or on this
beginning
all of whichhave sufferedhigh
lations,
otherconditionsmaskedthe inhabitat
it mightbe suspectedthat climortality,
of daylength.Sincethe resultsof
selectionhas eliminatedbiotypes fluence
matic
studies(2) of a populationof unearlier
thatcontinuedgrowth relativelylate.
origingrowingin a grasslandclithe fact that threeof the forty-one known
But
also furnishnegativeevidenceof
mate
studiedcontinuedcambialgrowtha
trees
controlover inceptionof
monthlater than all otherswithout photoperiodic
full
activity, the formerof the two
ill effectstherefromindicates cambial
exhibiting
mentionedaboveappearsto
the othersdo not explaitthe poten- possibilities
that
becorrect.
tialgrowingseasonto the extent of its
operated
If selectionhad
possibilities.
Summary
uponthis character,one would expect
in fortyI. Radialgrowthwas studied
thesurvivorsof the decimatedpopulaPinus ponderosa
to includea highpercentageof indi- onetrees including
tions
Engelm.,
scopvZorgns
var.
its
and
Laws.
late.
that continuegrowthrather
viduals
year I 948. These
Butthis is definitelynot true.If the de- duringthe calendar
populationsobtained
ceasedtrees were ones that continued treesrepresented
over a wide areain
late, they musthavedifferedto a fromknownsources
growth
UnitedStatesand had been
verygreatextentfromthe survivors.The thewesternthe same habitat at Priest
conclusiontherefore seems warranted growingon
Forestin northern
thatthe terminationof cambialactivity RiverExperimental
I 9 I I-I 9 I 7.
is strongly determinedby autogenous Idahosince datesforcompletionof 5%on
Median
2.
the
forcesand occurswell in advanceof
and 95%oof total radial growth
Cli- 50%on
onsetof criticallylow temperatures.
2I, and August 22.
maticselectionmust have operatedon wereMay 23, June
was considerablevariaphysiologiccharactersother than late- Althoughthere seasonswithin population in growing
nessof camlSialactivity.
but little difference
Althoughthere is considerablediffer- tions, there was
Susceptibilityto
populations.
the
enceamongindividualswithinonepopu- among
doesnot appearto be corlation, there is a strikingsimilarityin frostdamage
radialgrowththat continues
periodsof radialgrowthamongpopula- relatedwith
In thesefourteenpopseason.
the
in
tions originatingin widely differentcli- late
nearly I4° of latimatictypesandlatitudes.Thiscontrasts ulationsrepresenting
appearsto exertno influsharplywith the relativelyuniformap- tude,daylength
season.Duration
growing
the
upon
pearanceof treeswithineachpopulation ence
not related to
is
activity
but distinct differencein appearance of cambial
groupingof the populationsinto raceson
amongthe populations(6).
morphologyand anatomy.
Deviationsof particularpopulations the basis of
LITERATURE CITED
XEt.F. An improved type of preI. DAUBENMIRE,
cisiondendrometer.Ecology26:97-98. I945.
2.
. Re]ation of temperatureand daylength
to the inception of tree growth in spring. BOT.
GAZ.I IO:464-475. I9493. DAY,W. R. Local climaticeffectsin treegrowth.
BOTANICAL GAZETTE
I88Quart.Jour. Roy. Meteorol. Soc.
I 946
72; I76-I78.
I
4. KE1WPFF,
G. Non-indigenouswesternyellow pine
plantations in northern Idaho. Northwest Sci.
2: 54-58.
I928.
5. MUNGER,
T. T. Growth of ten regional races
of ponderosa pine in -six plantations. Pacific
[DECEMBER
Northw. For. Exp. Sta., For. Res. Note 39. I947.
6. WEID1WAN,
R. H. Evidencesof racialinfluencein
a 2s-year test of ponderosapine. Jour.Agr. Res.
59:855-888. I939.
7. WETTSTEIN,
W. VON.(Possibilitiesof breeding
new ecotypes by hybridization.) Zuchter I4:
282-285 (see For. Abstr. 9: IIO). Ig42.
EFFECT OF 2,4-D ON CARBOHYDRATEAND NUTRIENT-ELEMENT
CONTENTAND ON RAPIDITY OF KTTJTJ
OF SOYBEANPLANTS
GROWINGAT DIFFERENT NITROGENLEVELSI
DALE E. WOLF,2 GERTRUDE VERMILLION,3 ARTHUR WALLACE,4
AND GILBERT H. AHLGREN 5
greenhouse
in sandcultureat threenitroIntroduction
gen
levels
high (336 p.p.m.), medium
The physiologicalresponseof plants to
(56
p.p.m.),
and low (I4 p.p.m.)-and
the selective herbicide 2,4-dichlorophethen
a
drip
aqueous
solutionof 20p.p.m.
noxyacetic acid (2,4-D) is for the most
2,4-D
(the
sodium
salt
of 2,4-Dwasused)
part an unexplainedphenomenon. Some
was
added
to
the
cultures.
Plantsgrowspecies are readily affected, whereas
ing
on
high
nitrogen
were
affected
much
others are more or less resistant. Most of
more
rapidly
than
were
those
growing
at
the grasses are particularly resistant to
low
and
medium
levels.
Plants
growing
injury from the usual applications of
2,4-D. Occasionalinformal reports have on low nitrogenwereleast affected,and
indicated that rapidlygrowingplants are the plantson mediumnitrogenwerebeplants
more easily destroyed by 2,4-D than are tweenthe low- and high-nitrogen
in
response
to
2,4-D.
those growingslowly. Some investigators
The resultsof this test were of sufii(4, 5, 8) have suggested that the herbicient
interestto warrantfurtherstudyof
cidal properties of 2,4-D are related to
the
effect
of applicationsof 2,4-D on
the carbohydrate storage and nitrogen
plants
growing
at different nitrogen
metabolism of plants.
levels.
Therefore,
an attempt has been
In an experimentto determinethe relmade
to
relate
growth
status with the
ative effectiveness of 2,4-D on soybean
speed
and
intensity
of
plant
responseto
plants growing at different nitrogen
2,4-D
applications
and
to
determine
cerlevels, a pilot experimentwas conducted
tain
associated
physiological
changes.
by the senior author in I947. Duplicate
pots of Chief soybeanswere grownin the
Materialand methods
I Paper of the JournalSeries,New Jersey AgriculturalExperimentStation, RutgersUniversitythe State Universityof New Jersey,departmentsof
Farm Cropsand Plant Physiology.
2 Agent, Bureau of Plant Industry, Division of
Cereal Crops and Diseases, U.S. Department of
Agriculture; 3 Assistant Professor of Chemistry;
4 Graduate Fellow in Soils; 5 Professor of Farm
Crops.
Threeplantsof the Lincolnvarietyof
soybeansweregrownin sand culturein
the greenhousein each of twelveglazed
2-gallonpots fromFebruary27 to April
23, I948. Until the plants reachedthe
six-leafstage, a uniformnitrogenlevel
was maintainedby flushingthe sand