41

ARNOLDIA

A continuation of theBULLETIN OF POPULAR INFORMATION

of the Arnold Arboretum, Harvard UniversityVOLUME 13 3 SEPTEMBER 11, 1953 3 NuMSERS 7-9

SEEDS OF WOODY PLANTS

Collecting - Cleaning - Shipping - Longevity

THE studies of seeds of plants, their collection, care and requirements forgermination, has been an intriguing one over the years. Much work has beendone, mostly with the seeds of cereals, annuals and trees used for reforestation.Text books on forestry have much detailed information concerning forest treeseeds, but the seeds of many woody ornamental plants have not been studied asthoroughly as many a commercial grower would wish. This bulletin has to dealwith such seeds, primarily with suggestions for their collection, care in storage,and shipping before they are sown. This information is taken from many sources.not the least of which are the first hand experiences here at the Arnold Arbore-tum where the propagators have been sowing such seeds for over 75 years. Thebest reference on the subject with an excellent bibliography, is "Woody PlantSeed Manual" written by the Forest Service, U.S. Department of Agriculture(Misc. Pub. No. 654, issued June 1948).

CollectingSeeds should not be collected until they are ripe, for in many cases, seed col-

lected prematurely may not germinate. Any collector who has had experience inthis field knows that there are various methods of determining the ripeness of thefruit - the shrivelling of the pod or the cord connecting the seed to the pod inthe legumes, the color or softness of the pulp of the fruit of Malus, Viburnumand Cotoneaster, and close examination of the cones of coniferous trees sometimeseven tested by determining the specific gravity of the unopened cones.

Seeds should be collected wherever possible from pure stands. There are manygroups of plants which cross pollinate easily, and when seed is collected fromarboretums or other closely planted collections of many species, there is ampleopportunity for hybridization. This is also true in nature, so that in order to in-sure good seed, collect it either in pure stands or from isolated specimens.

42

One very important fact to keep in mind is that the seed of many a variety,botanical as well as horticultural, may not come true to name." There are somecases admittedly, in which the variety will yield a surprising percentage of theseedlings true to name. Such is the case with Quercus robur fnstigiata. But therule is, that in most cases, the seed of the variety yields seedlings similar to thespecies.The actual date seed ripens in one locality may vary from year to year in the

same way and for the same reasons as do the blooming dates of plants and theautumn color. Often one makes a special effort to collect seed of a certain plantonly to find on coming to the plant that all the seed has fallen on the ground orbeen eaten by the birds and rodents, or been partially destroyed by weevils. Theseeds of witchhazels, in particular, must be collected before the capsules open,for at that time they are actually thrown considerable distances by the explosiveopening of the capsule. Certain plants like Chionanthus virginicus, with fleshyfruits, may appear ripe one day and be gone the next, merely because a flock ofbirds have taken them all from the plant in a few hours time. This has happenedwith this plant on several occasions in the Arboretum.There are many plants which retain their fruits for a long time in the fall, and

far into the winter, the fruits of which may be collected over a long period. Manyof the seeds collected on the dates in the following list will have to be cleanedand dried, preferably in the greenhouse. Then there is an after-ripening periodor a period of dormancy for many seeds so that it is frequently months from thetime the seed is collected until it is ready for planting. However, when seed isto be obtained for special purposes, it is best to collect it as soon as it is ripe,instead of waiting too long and taking the chance of it disappearing. The follow-ing list of dates on which seed collections have been made in the Arboretum canbe considerably more flexible than the single date entry would lead one to believe.All these dates should be coordinated with the fruit ripening dates in the localitywhere the list is to be used, and collecting dates for many more can be insertedas they become known.

Seed Collection Dates-Chronologically

Ulmus americana

Populus tremuloides

Acer rubrumAcer saccharinum

Elaeagnus multiflora

Daphne mezereumLonicera coerulea

May 5L,lmus pumila .

Mav 1.~ 37Salix sp.

May 30Lonicera fragrantissimaLonicera standishi

June 5Prunus apetala

June 15 ,

Populus albaPrunus canescens

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June 20Amelanchier oblongifoliaCornus alba1runus sargenti

Prunus subhirtellaPrunus tomentosaViburnum fragrans

June 30Lonicera morrowi Prunus cerasus

July 5Amelanchier spicataCornus stoloniferaLonicera altmanniLonicera bellaLonicera chrysanthaLonicera maximowiczi

Lonicera muendeniensisLonicera nothaLonicera tataricaLonicera xy losteumMahonia aquifoliumNemopanthus mucronatus

Julv 10Jforus sp.Rosa agrestisRosa hugonisRosa roxburQhi

Rosa spinosissimaVaccinium vitis-idaeaViburnum tomentosum

July 30Amelanchier amabilisAmelanchier sanguineaPopulus maximowiczi

Rosa ecaeVaccinium corymbosum

August 5Ilex geniculataLonicera alpigenaPrinsepia sp.Prunus japonicaPrunus glandulosaPrunus maritima

Rhamnus frangulaRhus typhinaRibes odoratumRosa amblyotisRosa harisoniRosa primula

August 15 57Acer ginnalaCedrus libaniCeanothus pallidus roseusCornus racemosaCrataegus arnoldiada

Cytisus nigricans

Cytisus purpureusGaylussacia sp.Lonicera webbianaOstryavirginianaShepherdia argenteaViburnum sieboldi

August 20Berberis laxifloraBetula papyriferaCarpinus sp.Cornus baileviEhretia thyrsiflora

Kolkwitzia amabilisPrunus cerasiferaSpiraea veitchiViburnum alnifoliumViburnum lantana

August 30Berberis fendleriBerberis heteropodaCaragana maaimowiczianaCornus mas

Cornus kousaCotinus coggygriaCotoneaster racemifloraLaburnum sp.

45

Lonicera demissaLonicera orientalisLonicera tanguticaRosa carolinaRosa davurica

Rosa macouniRosa pendulinaSambucus canadensisSyringa amurensisViburnum trilobum

September :iAcer negundoBerberis vernaeCladrastis sp.Cornus asperifoliaCornus glabrataCrataegus punctata

Potentilla fruticosaRhus copallinaRosa rugosaRosa reversaZanthoxylum americanum

September 15Acer griseumAcer pensylvanicumAesculus sp.Akebia quinataAronia melanocarpaBetula luteaBetula lentaBetula populifoliaBetula pendulaChionanthus sp.Clethra alnifoliaCyrilla racemifloraDeutzia sp.Evodia danielli

Lindera benzoinLonicera subsessilisPaeonia suffruticosaPhiladelphus virginalisRosa acicularisRosa albaRosa blandaRosa coriifoliaRosa rubrifolia .Rosa willmottiaeRosa woodsiSassafras sp.Schisandra chinensisViburnum wrighti

September 20Acer platanoidesAcer saccharumAralia spinosaBerberis henryanaBerberis poiretiCorylopsis sp.Cotoneaster adpressaCotoneaster ambiguaCotoneaster melanocarpaCotoneaster moupinensisCotoneaster nitens

Cotoneaster roseaCotoneaster tenuipesFagus sp.Halesia sp.Ilex yunnanensisKalopanax pictusNyssa sylvaticaPieris sp.Quercus sp.Viburnum dilatatum

September 30Actinidia argutaAilanthus altissimaCercis canadensisClerodendron trichotomumCornus sanguineaExochorda sp.

Koelreuteria paniculataLonicera ibericaPinus sp.Rosa gallicaSymplocos paniculata

October 5

Ampelopsis sp. Berberis amurensis

46 .

Berberis bretschneideriCornus floridaCotoneaster foveolataFothergilla sp.Hamamelis sp.Larix sp.D7agnolia acuminataMagnolia soulangeanaMagnolia stellataRobinia sp.

Acanthopanax sp.Aronia arbutifoliaAronia prunifoliaCelastrus sp.Cotoneaster acutifoliaCotoneaster bullataCotoneaster dielsianaCotoneaster divaricataCotoneaster lucida

Abies sp.Berberis chinensisBerberis gilgianaCaragana arborescensCastanea mollissimaCeltis occidentalisChaenomeles lagenariaClematis paniculataCorylus americanaCorylus avellanaCorylus cornutaDavidia involucrataEuonymus alataEuonymus americanaEuonymus bungeanaEuonymus fortunei vegetaEuonymus nikoensisEuonymus obovataEuonymus sanguineaFraxinus sp.Ginkgo biloba

Albizzia julibrissin roseaAlnus glutinosaBerberis vulgarisBuddleia sp.Cercidiphyllum japonicumCrataegus oxyacantha

Solanum dulcamaraSorbaronia jackiSorbus sp.Vaccinium oldhamiViburnum betulifoliumViburnum carlesiViburnum cassinoidesViburnum dentatumViburnum ovatifoliumViburnum prunifolium

October 10Cotoneaster zabeliEnkianthus sp.Euonymus bulgaricaHydrangea petiolarisLonicera ferdinandiPseudotsuga taxifoliaSymphoricarpos sp.Taxus sp.Tsuga sp.

October 15Hicoria sp.Ilex verticillata

_ Juglans sp.Juniperus sp.Leucothoe catesbaeiLiriodendron sp.Picea sp.Rhododendron sp.Rosa caninaRosa corymbiferaRosa eglanteriaRosa helenaeRosa hibernicaRosa horridaStewartia sp.Thuja occidentalisTilia sp.Ulmus parvifoliaViburnum acerifoliumViburnum setigerumVitis sp.

October 20Lycium sp.Malus baccata

. Malus toringoidesOxydendrum arboreumPhellodendron sp.Photinia villosa

47

Physocarpus sp.Viburnum hupehense

Berberis koreanaCotoneaster horizontalisCotoneaster integerrimaCotoneaster tomentosaGymnocladus dio~caGleditsia sp.Hippophae rhamnoidesIlex opaca

Baccharis halimifoliaBerberis aggregataBerberis canadensisCallicarpa sp.Cotoneaster multifloraElaeagnus angustifolia

Berberis thunbergiCotoneaster affinisElaeagnus umbellataFranklinia alatamahaLonicera bracteolarisLonicera henryi

Crataegus lavalleiCrataegus nitida

Cotoneaster rugosaCotoneaster salicifolia

Viburnum lentago

October 30Kalmia latifolia

.

Ligustrum sp. ,

Malus, many sp.Pseudolarix amabilisRosa arvensisRosa virginianaViburnum burkwoodiWisteria sp.

November 5

Myrica pensylvanicaPaulownia tomentosaRhodotypos scandensViburnum lobophyllumViburnum opulusViburnum sargenti

,

November 1 ~Lonicera korolkowiLonicera maackiPyracantha coccinea

Ribes fasciculatumRosa setigeraRosa wichuraiana

November 20Crataegus prunifoliaRosa multiflora

November 30

Crataegus phaenopyrumIlex glabra

Cleaning SeedsMost seeds must be cleaned in one way or another before they are sown. The

fruits of rosaceous plants, viburnums, magnolias, dogwoods and many other fruitswith pulp about the seeds must be cleaned before the seed is shipped or evenbefore it is stored in large quantities, for the rotting pulp quickly heats and inmany a case the high temperature will kill the embryos. On the other hand,many of the seeds produced in dry capsules like those of the ericaceous plants,spireas, mock oranges, etc., can be merely sun dried and then shipped.

Even elm seed must be dried before it is shipped. This seed is frequentlypicked while it is still slightly green on the tree, or picked up from the groundwhile it is damp, and if stored or shipped in large quantities before it is thoroughlydry, it may heat and be completely killed on arrival. This has happened to manyshipments arriving at the Arboretum.

There are many ingenious methods for cleaning seeds, some of them worked

48

out on the spur of the moment, Cones from coniferous trees, for instance, mustbe dried and in many cases have hot air applied to them in order that they willopen and thus allow the seeds to fall out. For small amounts, this is easily accom-plished in the hot sun or on the greenhouse bench, with the cones on screens sothat the seed will fall in the receptacle below. For large amounts, the forestershave invented several types of drying kilns.

Conifer seeds, and those of maple and ash and others like them, can be shippedwith the wings on, but should be dewinged before they are sown. This can beaccomplished in several ways, but for small amounts the best method is by handrubbing; or secondly, by lightly rubbing the seeds over a screen. Too muchpressure can injure the seeds, so care must be shown in this operation. Screeningand even fanning of the resultant mixture are means of separating chaff from seed.Some of the larger seed can be handled by regular farm machinery. Hulls of

the black walnut, for instance, can be removed by running the fruits through thecorn sheller. Various fruits can be run through threshing equipment in order toproduce clean seed.

Finally, the pulpy seeds are usually cleaned by macerating them and soakingthem in water during which process the pulp and poor seeds usually float to thesurface and can be removed while the viable seeds sink and can be later driedfor storage and shipping. Acorns have been "cleaned" by the water methodsince the cups and weeviled acorns float and the viable acorns sink to the bottom.Naturally, the amount of seed to be cleaned governs the method chosen.

For small amounts of seed, we have found the Waring Blender most service-able. This has been used by several institutions (or possibly other makes as well).We removed the metal blade of this electrically operated household machine andsubstituted one cut from the casing of an automobile tire instead. This is a smallpiece of rubber, 1 ~ inches square held horizontally on the revolving axis of themachine, which does not injure the seeds. The standard whirling metal bladewhich comes with the machine can quickly scarify and injure the seeds of manyplants, hence it should not be used. Even with the rubber blade, the fruits shouldbe completely ripe so that the flesh is easily macerated (or else it should be partly y.macerated in advance by hand) and the seed put in for no longer than two minutestogether with an ample supply of water. The length of time depends on the kindof seed, its degree of softness and the amount of seed. None larger than the fruitsof Prunus americana or P. hortulana can be used. Obviously, only small amountsof seed can be handled in this fashion, but undoubtedly larger equipment couldbe made if necessary. This method has proved a timely and quick one with us,for cleaning small amounts of pulpy seed.Many seeds are sun dried after the cleaning process and sown, stratified or

stored, but for those who want to be certain no disease gets into the seed, asimple treatment with some disinfectant such as washing in a 3-10 per cent solu-tion of potassium permangenate might be well worth the effort. To kill weevils

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and worms and any other insects, the seeds could be dusted with rotenone, avail-able in most countries. With acorns, carbon bisulfide has been used to kill the

weevils, a small amount placed in a large covered container and the acorns leftin long enough to kill the weevils. Naturally the amount of the chemical useddepends on the size of the container and the amount of seed to be disinfected.This may not prove suitable for all kinds of seeds.

Shipping SeedsWhen seeds must be sent long distances over land or sea, great care should be

taken in their packing and the means by which they are shipped. Every seedcollector should know something about the seeds he is sending, how they shouldbe cleaned, and which ones should be shipped as soon as collected. This last pointis a very important one. Unfortunately many institutions shipping seeds fromabroad and many a botanical collector as well considers that all seeds can behandled alike, that is, they can be stripped from the plants in the fall, cleanedwithin a month or so and held possibly for six months until all the seeds are readyfor shipment at one time or until weather conditions are such that the collectorcan take the time to ship them.The Arnold Arboretum has had many sad experiences with shipments sent off

by such individuals. It will be noted from the following lists that some seeds cannot be allowed to dry out and should be shipped immediately as soon as they arecollected. Certain seeds like those of Populus, Salix, Magnolia and Ulmus shouldalways be shipped promptly by air since they will remain viable for only a veryshort time even under the best of conditions. Willow seeds may remain viable

only a few days.Seed that is important enough to collect and clean (especially rare seed) is

valuable enough to ship by air whenever possible. Last spring the Arboretumreceived two identical shipments of seeds from Argentina, collected at the sametime. One consignment was sent by air and arrived four days after mailing. Thesecond consignment mailed the same time but sent by regular mail (boat) arrivedone month later and ~?5 per cent of the packets failed to germinate, whereas only1 per cent failed in the first air-shipped lot.

Cleaning has already been discussed, but in shipping seeds, certain types likethose of Cytisus, Robinia or Quercus are susceptible to attacks of weevils or otherinsects and if the period of shipment is long and slow, it may well be that theseed will be worthless on arrival. Such seeds should be treated with some ma-terial to kill such pests. Carbon bisulfide gas has been used satisfactorily herewith acorns, but the amount used depends on the size of the closed container inwhich the fumigating is to be done, the amount of seed and even kind of seed.One excellent suggestion has been that rotenone dust be used for dusting oversuch seeds when they are placed in the packet, the amount of dust used beingequivalent to one-fourth the bulk of the seeds.Any seeds that might be unusually susceptible as disease carriers might be

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treated with a mild disinfectant, such as a 5-10 per cent solution of potassiumpermangenate, then dried and bagged for shipment.

It will be noted in the following lists that some seeds should not be allowedto dry out in transit (List A). This is a most important group of seeds and it issafe to say that we have been unable to germinate hundreds of groups of seedssent us here, merely because the collectors failed to recogmze the importance ofthis fact. Only last year a Japanese botanist who should have known better,collected seeds for us in one of the higher and colder parts of Japan, but he keptall his seeds until he was finally ready to send them in one shipment. As a re-sult, 45 per cent of the seed numbers he had sent (159 packets in all) failed togerminate, a discouragingly large amount when one considers the efforts he spentat his end to collect them and the efforts to which we went here to record andsow them.The old fashioned method in shipping seeds, used frequently by E. H. Wilson

so they would not dry out in transit, was to pack them in charcoal. Moist sawdust or moist peat moss is not good if the shipping period is long or hot, for theseeds may either start to germinate, or high temperatures may cause the packingmaterials to heat and kill the seeds. Charcoal, however, proved an excellentmedium for it does not absorb moisture.

Polythene bags can now be used to excellent advantage. This material is widelyused in America for packaging vegetables, is very light and can be sent to col-lectors in the field if need be. We are sending cuttings, scions, budwood, andplants wrapped in this material to many parts of the world and doing it satisfacto-rily. The polythene film does allow a small movement of gaseous vapors through,but not water vapor (See Arnoldia 1 I : Nos. 7-8, Oct. 26, 19~ 1 ~. Bags made ofpolythene should be tightly sealed, could contain several paper packets of seedsand even a very small amount of moistened moss to keep the small amount of airin the bags slightly humid, for those seeds that should not dry out. Anothermethod for shipping such seeds as acorns or chestnuts would be to dip them inparaffin. We have sent seeds treated this way successfully to Norwar , Italy andPalestine and they quickly germinated after planting.Each seed packet should be tightly sealed and clearly marked with the follow-

ing information :1. Scientific name of plant from which collected.

>>. Date collected.3. Location where collected.4. Any pertinent information about the plant if it varies from the species or

if its name is unknown.The plant quarantine laws of the United States prohibit the entry of some

seeds into this country. None can be sent in with moist pulp about them. In thenorthern part of the United States the more important woody plants the seedsof which are prohibited are Berberis species, Ribes nigrum, Bamboos and their

51

relatives. These same quarantine laws approve only certain packing materials suchas peat moss, sphagnum, excelsior, wood shavings, sawdust, ground cork, buck-wheat hulls, expanded vermiculite and charcoal.

Packing materials prohibited are soil, sand, leaves, forest litter, woods moss,hay, straw, etc. -anything taken from direct contact with the soil. Seeds packedin such materials will be prohibited entry.

Seeds collected in the United States for the Arnold Arboretum should be sent to :The HorticulturistArnold Arboretum, Harvard UniversityJamaica Plain 30, Massachusetts, U.S.A.

Seeds of woody plants collected in foreign countries and destined for recipientsin the United States must be accompanied by a permit. The Bureau of Entomologyand Plant Quarantine of the U.S.D.A. issues such permits to individuals and in-stitutions upon application. A number is given the applicant and this numberappears on a standard green and yellow tag bearing the address of the quarantmestation (Hoboken, N.J. ; Miami, Florida; Laredo, Texas; or San Francisco, Cali-fornia). This required tag is the only address appearing on the outside of thepackage other than the collectors name and address in the upper left hand cor-ner. The Arnold Arboretums permit number is 3 i-1738, and collectors in foreigncountries should request these permits from the Arboretum in advance of seedcollecting and for the port of entry most convenient.

"Seeds for Experimental Purposes only - no commercial value" should beclearly written on the outside of the package from a foreign country. Inside thepackage should be the address of the Arboretum and a list of the seeds enclosed.These regulations are required by the "Ilant Quarantine Act #3 i " and shouldbe followed to insure foreign seeds reaching their proper destination in the UnitedStates. A 10 per cent DDT dust might be mixed with the seeds to kill insects.The following three lists do not contain all those woody plants commonly grown

from seed but they should serve as a guide to collectors to indicate how certainseeds should be handled and how rapidly they should be shipped. Special em-phasis should be placed on list "A" as the "perishable" group. List "B" con-tains those which can be sown or stratified at once or dried and used later. List"C" contains those which can be kept in a dry condition, some of them forperiods longer than one year.The procedure in shipping seeds of all woody plants should therefore be:1. Clean all seeds thoroughly and at once, taking special precautions not to

allow pulpy or wet seeds to "heat" before cleaning.2. Prevent certain seeds from drying out-List "A"-by proper packaging.3. Properly dry the remainder.4. Fumigate or in other ways treat for insects or disease pests if necessary..i. Label all seed packets completely.6. Ship as soon as picked (and by air) those in L~st "A."

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7. Send the remainder of the shipment as soon as possible, keeping the seedsdry and away from contamination with insect and disease pests.

A. Seeds that should not be allowed to dry out in shipping(These should be shipped immediately as soon as ripe. They should be sent great distancesonly by air and should be sown as soon as received. Special precautions should be taken inpackaging these for shipment so that they will not dry out enroute, otherwise, they may beworthless on arrival at their destination. Some will remain viable only a few days (Salix);

others a few weeks to six months (Cedrus).AcerAesculusAlnusAmelanchierAmpelopsisAraliaAsiminaCarpinusCaryaCastaneaCedrusCercidiphyllumChamaecyparis lawsonianaClerodendronCryptomeria

DavidiaDiospyrosFagusFrankliniaHalesiaJuglansLiriodendronLinderaLiquidambarLyciumMagnoliaMahoniaMyricaNandinaNyssa

Ostrya aPopulusPotentillaQuercusRhusSalix

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SassafrasShepherdiaSophoraSpiraeaStaphyleaStewartiaStyraxUlmusZelkova

B. Seeds that can be sown or stratified as soon as ripe ordried and sown the following spring

(These need not necessarily be shipped quickly by air, but can be sown or stratified as soonas received from the collectors.)

BerberisBetulaBuxus

CaraganaCelastrusCeltisChaenomelesChionanthusCladrastisCornus

Cotoneaster. CrataegusElaeagnusExochordaGinkgoGleditsiaHippophaeIlexJuniperusLigustrum

I

Lonicera

MalusPhellodendronPrunusPyracanthaRhodotyposRobiniaTaxusViburnum

C. Seeds that can be stored dry and sown within the year(These can be stored and shipped dry, and can be held dry on receipt from collectors.Naturally all seed should be shipped as soon as reasonably possible by the collector, butthis group can be held the longest and does not deteriorate as rapidly in shipment as

seeds in List "A.")ActinidiaAkebiaAilanthusAlbizziaAmorphaAronia

AtriplexCallicarpaCalvcanthusCaryopterisCatalpaCercis

ChamaecyparisCupressusCytisusElaeagnusDeutziaDiervilla .

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EuonymusEvodiaFraxinusHibiscusKalmiaKoelreuteriaLaburnumLagerstroemiaLarixLeucothoeLibocedrusMetasequoia

MorusPaulowniaPhiladelphusPhysocarpusPiceaPinusPlatanusPseudotsugaPyrusRhododendronRibesRobinia

RosaSciadopitysSophoraSorbusSymphoricarposSyringaTaxodiumThujaTsugaVacciniumVitexWisteria

LongevityThe longevity of ornamental woody plant seeds has not been given exhaustive

study. The United States Department of Agriculture reviewed the literature onthis subject in its "V~oody Plant Seed Manual" Misc. Pub. No. 654, issuedJune 1948, and for detailed information the reader is directed to this publicationand its excellent bibliography.The longevity of seeds depends on the kind of seed, where and how it was

grown and matured, the conditions under which it is stored, etc.-all variablefactors. Poplar seeds lose their viability very fast and must be sown within a fewweeks of ripening-willow seeds are viable even a shorter time. Experimentationhas shown that many annual garden flower seeds are viable under normal condi-tions for 2-3 years and many 4-5 years. Many vegetable seeds are good up to10 years (beets, cucumber, radish), many of the cereals from ?-13 years, and certain weed seeds like smartweed, moth mullein and evening primrose germi-nate after having been stored in inverted bottles in the soil fifty years. The re-cent classic example of Lotus seeds which have proved to be 100(1 years old andgerminated is the extreme.

Experiments in dormancy and the keeping qualities of seeds have shown thatlongevity usually increases with a drop in the temperature of the stored seeds, sothat now it is generally believed that temperatures of 320-410 F are ideal forseed storage, especially when the moisture content of the seeds can be maintaineduniformly. illany commercial nurseries have mechanical refrigeration equipmentnow which can be easily regulated and such equipment is proving almost a neces-sity in the storage of woody ornamental plant seeds.

Suffice it to say that although some woody plant seeds can be satisfactorilystored for a year or two in open containers at room temperatures, by far thegreater proportion can be kept longer if stored in air tight containers at tempera-tures between 3 ~-41 F.

There are numerous problems connected with the breaking of the dormancyof the seeds of ornamental woody plants and accurate information on their lon-gevity is meagre. Most of the following listed information has been taken fromthe "V~oodv Plant Seed D9anual" but some has been inserted as a result of the

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experience with these seeds we have grown at the Arnold Arboretum. Here isrecorded the approximate time during which woody plant seeds can be stored(not sown or stratified) and still retain some viability. Naturally, the longer thestorage period the less the viability in most cases.The column on the left indicates the time in years that seeds can be stored

normally (dry and at room temperatures) and still be viable. The column on theright indicates the time in years that the seeds can retain some viability whenstored (not sown or stratified) in air tight containers at approximate tempera-tures of 3l-41 F. It should be pointed out that those plants in List "A"page ~4 do not appear here merely because it is a known fact that they must besown quickly after they mature and before they dry out. This following list ismost incomplete and if nothing else, it serves to point out the fact of what littlewe know about the longevity of these seeds and in some cases, how really shortlived they appear to be.

Longevity of Seed in Storage(All those in list "A" page 54 have very short longevity at room temperatures)

AbehaAbies alba

balsameaconcolorgrandisprocera

Acer ginnalamacrophyllumnegundopensylvanicumplatanoidespseudoplatanusrubrumsaccharinumsaccharumspicatum

ActinidiaAkebiaAilanthus altissimaAlbizzia julibrissinAlnus glutinosaAmelanchierAmorpha fruticosaAroniaAtriplex sp.Baccharis

Ordincary storage Sealed atorage .S~-l~1 F(i~a yvars) (in yrarg)

1

less than I ~-4

1_~

. c /115

2isow at once-cant be stored

1~ %1 ~-

1-2 2-~1

1-~l

1~3 .1-I-J

1 i1

3-51

6-76 mos.

J~

BerberisBetula lenta

luteanigrapapyriferapendulapopulifolia

BuddleiaBuxus

CallicarpaCaragana arborescensCarya sp.Catalpa bignonioides

speciosaCeanothus americanusCelastrusCeltis laevigata

occidentalisCephalanthus occidentalisCercisCerocarpus montanusChaenomelesChamaecyparisChionanthus virginicusCladrastis .ClematisClethraComptonia peregrinaCornus florida

racemosa

CorylopsisCorylus americana

avellanacornuta

CotinusCotoneaster

Crataegus mollisCupressus arizonicaCyrillaCytisusDavidiaElaeagnus angustifoliacommutata

DeutziaDiervillaI~pigaea repens

1

1~1~

1~

1~1l15

22

8

15

1121

22

1

1

1-2

1

1

31-2

1

13 mos

J22

22

3-,)

2t+

314

2!

1222+1

2+

2+

2+2+8-10

3.51

58

EnkianthusEuonymus atropurpurea

europaeusverrucosus

EvodiaExochordaFagus grandifolia

sylvaticaFothergillaFraxinus excelsior

nigraoreganapennsylvanicaamericanadipetala

Gaultheria procumbensGaylussacia baccataGinkgoGleditsiaGymnocladus dioicusHamamelis virginianaHippophae rhamnoidesHydrangeaHypericumIlexJuglans cinereaJuniperus ashei

pachypodascopulorum

KalmiaKoelreuteria paniculataLaburnumLarix decidua

laricinasibirica

LeucothoeLibocedrus decurrensLigustrum vulgareLiquidambar styracifluaLonicera tataricaMaclura pomiferaMalus pumilaMetasequoiaMorus albaMyrica ceriferaPaeonia suffruticosa

I

22

211

2-31 ~-31

3

1

~-2

1-2

1

2

4

5

8~2+101

3-4

231-2

0

23

2+2+2+

1

1

13-6

42

2

2

2

2+

1-~4-5

3-4+6

)+

1+

2+~21 2

1-2

59

ParthenocissusPaulowniaPhellodendronPhiladelphusPhysocarpuslicea

abiesengelmanniglaucamarianarubens

PierisPinusattenuata

banksianacaribaeacontorta latifolia

coulteridensifloraechinataflexilishalepensisjefleeyilambertianamonticolamugomuricatanigrapalustrispinasterponderosapungensresinosarigidastrobussylvestristaedathunbergivirginiana

PrinsepiaPrunus americana a

armeniacaaviumpensylvanicaserotinavirginiana

Pseudotsuga macrocaryataxifolia

Itelea trifoliataPyracanthaPyrus communis

1RZ1

5+5+10+5+10+115 (on trees)

30 + (on trees)1-4 4

62+8

21-220+ (on trees)2+2+8-4

9+ (on trees)8-~

1

l~1-21-~1

1410 0

1

2+

!0+(?)

10+5+97+

t+

10+10+

5-9

6

10+2+8+187-9!+5+

4

t+2

4-4t+

60

Quercusrobur

Rhamnus alnifoliadavuricacathartica

RhododendronRhodotypos scandensRhus glabra

typhinaRibes americanum

cynosbatiRobinia pseudoacaciaRosa

.

Rosa blandaRubus idaeus

occidentalisSambucus canadensis

pubensSapindus drummondiSequoia sempervirensSequoiadendron giganteumShepherdia argenteaSorbus americana

aucupariaSymphoricarpos albusSyringa vulgarisTaxodium distichumTaxus baccataThuja occidentalis

plicataTilia americana

cordataTsuga canadensis

heterophyllaUlmus americana

pumilaVacciniumViburnum acerifolium

cassinoideslentagoopulustrilobum

Vitex agnus-castusVitis ripariaWisteriaZanthoxylum americanumZelkova

2

9 mos

73-43-5 when stratified8-~

1~

2

2~1-26 mos

222-8

2-3

2

2

2

3-4826 mos

8-~-?

~810-~

1-21-~Q .2

18-248~8

4

6 mos ~4+5

4-6

2+4

21-~-2~

ii+12

22+

DONALD WYMAN