ARNOLD ARBORETUM HARVARD UNIVERSITY ARNOLDIA A continuation of the Bulletin oe Popui.ar Ineormation VOLUME XIII 1953 finjr Hcrbanum Harvard Universitv JAN 8 185^1 PUBLISHED BY THE ARNOLD ARBORETUM JAMAICA PLAIN, MASSACHUSETTS Digitized by the Internet Archive in 2017 with funding from BHL-SIL-FEDLINK https://archive.org/details/arnoldiaarno_10 ARNOLDIA (aray Herbarium Harvard University H 13 1953 A continuation of the Bulletin of Popular Information of the Arnold Arboretum, Harvard University Volume 13 MARCH 6, 1953 Numbers l-i2 SOMP: of the best vines and ground COVERS FOR MASSACHUSETTS GARDENS* During the past two years, two issues of Arnoldia have dealt with some of the best shrubs and trees for Massachusetts gardens. (Arnoldia 1 1 : No. 1, March 9, 1951 ; Vol. 12: No. 1, March 7, 1952). This issue, dealing with vines and ground covers will complete this series. Everything which was said in those bulletins on what constitutes “the best” and how such plants are chosen, is also applicable here to the vines and ground covers. It should be re-emphasized here however, that nothing is implied in the following discussions of the selected types. that would indicate some of the others listed on pages 18 and 19 are not just as serviceable. The recommended ones might be used considerably more than they are at present. It is especially important to note that each plant in the following list is avail- able from at least one of the listed nurserymen. It was impossible to contact all the nurserymen in the state, so there are undoubtedly many other sources in the state for these plants. Since they are available, your local nurseryman can obtain them for you, if he will. Glowing descriptions of plants that are unobtainable may play on the imagina- tion, but it is useless to become enthusiastic about them until they are obtain- able. Each one of these listed is available in 1953. Consequently, the gardeners of the state are urged to become better acquainted with these vines and ground covers, buy a few that are hardy and in this way increase the beauty and interest of the home grounds. * This list was prepared at the request of the Horticultural Committee of the Garden Club Federation of Massachusetts, and is a companion list to those published in Arnoldia for March 9, 1951 (Shrubs) and March 7, 1952 (Trees). It is not perfect and many may take exception to it. However, it does include the 35 top notch vines and ground covers that can be used more in our gardens today. Most important, all are available in 1953 from local nurseries! Thirteen of the Best Vines for Massachusetts Gardens Akebia quinata Ampelopsis brevipedunculata Campsis tagliabuana “Mine. Galen" Clematis inontana rubens Clematis texensis Clematis vitalba Euonymus fortunei colorata Hedera helix baltica Hydrangea petiolaris Lonicera henryi Polygonum auberti Wisteria floribunda macrobotrys Wisteria floribunda rosea Fiveleaf Akebia 2, 4, 5, 6, 7, 8, 9 Porcelain Ampelopsis I, 2, 6 Var. of Trumpet Vine 2, 4, 5, 6, 7, H Pink Anemone Clematis 2, 6, 7, 8, 9 Scarlet Clematis 6, 7, 8, 9 Traveler's Joy .5, 6, 9 Purpleleaf Wintercreeper 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Baltic Ivy 1, 2, 3, 4, 5, 6, 7, 8, 10 Climbing Hydrangea 1, 2, 3, 4, 5, 6, 7, 8, 9 Henry's Honeysuckle 2, 4. 6 Silver Fleece Vine 1, 2, 3, 4, 6, 7, 8 Longcluster Japanese Wisteria 6, 10 Bose Japanese Wisteria 8, 10 Twenty three of the Best Ground Covers for Massachusetts Gardens Aegopodium podograria Arctostaphylos uva-ursi Cytisus purpureus Diervilla lonicera Euonymus fortunei kewensis Euonymus fortunei minima Forsythia “Arnold Dwarf" Hypericum buckleyi Indigofera incarnata alba Indigofera kirilowi Iberis sempervirens “White Gem” Juniperus horizontalis Juniperus horizontalis plumosa Juniperus chinensis sargenti Leiophyllum buxifolium Leucothoe catesbaei Lysimachia nummularia Pachistirna canbyi Pachysandra terminalis Rhus aromatica Rosa wichuraiana Teucrium chamaedrys Xanthorhiza simplicissima Bishop's Goutweed 8 Bearberry 2, 4, 6, 7, 8, 10 Purple Broom 5 Dwarf Bush Honeysuckle 5, 6 Kew Wintercreeper 1, 2, ‘5, 6, 7, 8 Baby Wintercreeper 2, 3, 6, 7, 8, 9, 10 2, 5, 8, 10 Blue Ridge St. Johnswort 0, 8 White Chinese Indigo 5 Kirilow Indigo 5, 6 Var. of Evergreen Candytuft 2, 3, 7,8 Creeping Juniper 1, 4, 6, 7, 8, 10 Andorra Juniper 1, 2, 3, 4, 6, 7, 8, 9, 10 Sargent Juniper 2, 5, 6, 8 Box Sandmyrtle 4, 8, 10 Drooping Leucothoe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Moneywort 6, 8 Canby Pachistirna 2, 4, 5, 6, 7, 8, 10 Japanese Spurge or Pachysandra 1,2,3,4,6,7,8,9,10 Fragrant Sumac 1, 6, 7, 8 Memorial Rose 2, 6, 7, 8, 9, 10 Chamaedrys Germander 1, 2, 5, 6, 7, 8, 10 Yellow-root 1, 2, 4, 5, 6, 7 Sources for Vines and Ground Covers Listed 1. Adams Nursery, Inc., Westfield, Mass. 2. Bay State Nurseries, North Abington, Mass. 3. Cherry Hill Nurseries, West Newbury, Mass. 4. Harlan P. Kelsey, Inc., East Boxford, Mass. 5. Kingsville Nurseries, Kingsville, Maryland 6. Henry Kohankie and Son, Painesville, Ohio 7. Littlefield-Wyman Nurseries, 22? Centre Ave., Abington, Mass. 8. Weston Nurseries, Inc., Weston, Mass. 9. Wyman’s Framingham Nurseries, Framingham, Mass. 10. Tingle Nurseries, Pittsville, Maryland [-C Clematis montana ruhens. The Pink Anemone Clematis introduced into America by the Arnold Arboretum can become a real garden asset if the soil conditions are slightly alkaline. VINES FOR DIFFERENT PURPOSES 'I'he following lists of vines are suggested for different purposes hut are not in- fallible by any means. Certain vines can be made to grow on banks or in the shade, or be used as ground covers with a little careful training and fertilization when normally they would not be expected to do well under such conditions. The interested gardener will want to experiment on his own with other varieties, and may be rewarded with success if he goes about making his selections intelligently. Twining Vines Actinidia species Celastrus species Akebia quinata Lonicera species Aristolochia durior Polygonum auberti ' Wisteria species Clinging Vines (clinging to stone and wood) Campsis species Hedera species Euonymus fortunei varieties Hydrangea petiolaris Parthenocissus tricuspidata and varieties Vines climbing by means of tendrils or twining leaflets Clematis species Vitis species Vines for Flowers Campsis species Lonicera species Clematis species Polygonum auberti Hydrangea petiolaris Wisteria species Vines for Colorful Fruits Ampelopsis brevipedunculata Clematis — most species Celastrus species Parthenocissus species Euonymus fortunei vegeta Vines Withstanding Shade Actinidia species Akebia quinata Aristolochia durior Clematis species Euon.vmus species Vines Withstanding D Campsis radicans Clematis texensis Polygonum Hedera species Hyd rangea petiolaris Lonicera species Parthenocissus species \^itis species ry Soil Conditions Parthenocissus quinquefolia Parthenocissus tricuspidata auberti [-1] Vines for Ground Covers Akebia quinata Celastrus species Euonymus obovata Hedera helix baltica Lonicera species Parthenocissus quinquefolia GROUND COVERS FOR DIFFERENT PURPOSES Ground Covers for Shade Aegopodium podograria Ajuga reptans Convallaria majalis Epimedium grandiflorum Euonymus fortunei and vars. Gaultheria procumbens Hedera helix Hosta sp. Idriope spicata Lysimachia nummularia Nepeta hederacea Pachysandra terminalis Vinca minor Xanthorhiza simplicissima Ground Covers for Dry Soil Aegopodium podograria Arctostaphylos uva-ursi Cytisus purpureus Gaultheria procumbens Hosta sp. Nepeta hederacea Rhus aromatica Sedum species Ground Covers which Aegopodium podograria Akebia quinata Ajuga reptans Cerastium tomentosum Convallaria majalis Diervilla lonicera Euonymus fortunei colorata Forsythia “Arnold Dwarf” Indigofera species Liriope spicata increase rapidly Lonicera species Lysimachia nummularia Nepeta hederacea Pachysandra terminalis Parthenocissus quinquefolia Polygonum reynoutria Rhus aromatica Rosa wichuraiana Sedum species Vinca minor Xanthorhiza simplicissima Ground Coyers less than 6 inches high Ajuga reptans Arctostaphylos uva-ursi Cerastium tomentosum Convallaria majalis Epimedium grandiflorum Euonymus fortunei var. Iberis sempervirens “White Gem” Juniperus horizontalis (usually) Liriope spicata Lysimachia nummularia Nepeta hederacea Pachysandra terminalis [5] Hydrangea petioJaris. This Climbing Hydrangea, growing on an elm tree by the Arnold ? Arboretum makes a wonderful display every year and does not injure the tree in any w'ay. > Gaultheria procumbens Gypsophila repens rosea Phlox subulata “Emerald Cushion’’ Sedum species Evergreen Arctostaphylos uva-ursi Calluna vulgaris Euonymus fortunei vars. Gaultheria procumbens Iberis sempervirens “White Gem’ Juniperus sp. and vars. ca minor Ground Covers Leiophyllum buxifolium Leucothoe catesbaei Liriope spicata Pachistima canbyi Pachysandra terminalis Vinca minor Hardiness Note: Plants listed as hardy in Zones 2,3, and 4^ are hardy through- out most of Massachusetts ; those hardy in Zone 5 can be safely grown only in the southern, eastern and southeastern parts of the state. VINES Akebia quinata Twining 30'— 40' Zone 4 Fiveleaf Akebia This is a dainty-leaved, vigorously growing twiner that makes one of the best foliage vines for this area. It is not new, has been in America for nearly a cen- tury, and in some cases where it has been allowed to grow unrestrained, has be- come just as much of a pest as bittersweet. However, it is not used nearly enough. The small purple flowers appearing in mid-May are not conspicuous, but are very interesting. As a delicate foliage vine, it has few peers. Since it climbs by twin- ing, it must have some upright support around which it can twine. Grown on a rainspout, it will climb to the top of a two story building in a few years time. When the spout must be removed for repairs or painting, the vine can be cut back to within two or three feet of the ground. If this is done in the early spring the vine can be expected to grow back in another two years. The leaves remain green on the plant until early winter. It requires no particular attention, and as far as we know, has no serious insect or disease pests. Ampelopsis brevipedunculata Zone 4 Porcelain Ampelopsis The Porcelain Ampelopsis climbs by attaching tentrils to a means of support. It has deeply lobed leaves, is not a dense vine like the Boston Ivy, but its most ornamental characteristic is its porcelain blue fruits in the early fall. No other vine in the North has fruits as colorful as these. Campsis tagliabuana “Madame Galen’’ Clinging 25' Zone 4 Var. of Trumpet Vine The larger flowers of this hybrid clone over the flowers of the common native Trumpet Vine (C. radicans) are its chief claim to added use. The flowers are orange [T] and scarlet, usually in diameter and like the other members of the genus it ; climbs by attaching small root-like holdfasts to the wall. Since the large flowered Chinese Trumpet vine is not hardy here, this hybrid might be used where its large flowers are wanted. Clematis montana rubens 24-' Zone 5 Pink Anemone Clematis | E. H. Wilson brought this beautiful plant into America from China. Although j it is not completely hardy in all parts of Massachusetts, and many people find I difficulty in meeting the exacting demands of the Clematis clan in order to grow them well, nevertheless it might be worthy of a trial for those who are willing to i study its needs and supply them. The flower buds are borne on the previous j year’s wood, hence it should not be pruned until immediately after flowering. > The flowers are rosy pink, about in diameter and appear in May, and the ! new young foliage is a reddish bronze color. Like many another clematis, the j plumv seed heads are also very interesting in the fall. : I [ Clematis texensis 6' Zone 4 Scarlet Clematis j A native Texan, there are a few gardeners in Massachusetts who are successful ! in cultivating this six foot vine. The bright scarlet flowers are bell shaped and profuse, appearing in July. If grown in a sheltered spot it may start to bloom in early summer and continue until frost. Although it may die to the ground in the winter, it grows quickly from the base, and since the flowers are borne on the current year’s growth, it can be expected, to bloom the same year. Like most other clematis varieties, it needs special soil conditions in which to do well. ! Clematis vitalba 80' Zone 4 Traveler’s Joy One of the vigorous-growing species, it does have small flowers so that its rapidity of growth, its late summer bloom and its very fluffy seed heads in the i fall are its important features rather than the size of the individual flowers. The i common name comes from the fact that the white flowers of this European native j are slightly fragrant, and the odor proves quite refreshing to the traveler on a 1 hot summer’s day. An excellent vine for growing over fence or garden pergola j where dense foliage is wanted. i Euonymus fortune! colorata Zone .5 Furpleleaf Wintercreeper | Th e so-called Furpleleaf Wintercreeper is good as a low vine and especially a ! ground cover. It is not completely evergreen, but in the fall its inch-long leaves turn a brilliant purplish red, making it a very effective fall plant. This fall color ; may last for several months, long into the winter. Like the other Euonymus, it i climbs by means of attaching small root-like hold fasts to wall or tree trunk, , hence it should not be used to climb on wooden buildings. [8] PLATE III Polygonum auherti. The Silvervine Fleeceflower is an excellent late summer flowering? vine that needs some support for climbing?. Even though it may be killed to the ground in severe winters, it will come back with sufficient vigor to bloom the current year. Hedera helix baltica Clinging 90' Zone 4 Baltic Ivy B-very one is familiar with the English Ivy, but it is not completely hardy in all parts of Massachusetts. The variety baltica is supposed to be the hardiest vari- ety available at present. It is growing to the top of the three story brick admin- istration building of the Arnold Arboretum, on the north side, and has been there for nearly forty years. It must be admitted that this is a sheltered situation, and even here, during some of the more severe winters it is partly injured, but many a winter it comes through unscathed. Consequently, if English ivy is to be used, this variet.v might be expected to do best. On Cape Cod it grows to the top of thirty foot trees, but in most colder situations it is best to try it only in sheltered situations, especially those with northern exposures. Hydrangea petiolaris Clinging 73' Zone 4 Climbing Hydrangea Although this excellent vine has been growing in the Arnold Arboretum since 1892 it has not been as widely used as it merits. This may be partly due to the fact that young plants take several years before they become well established and really start to grow. It is a true hydrangea, and climbs by root-like hold fasts which attach themselves to brick, stone or tree trunk. It should not be used on a wooden building, obviously. It does not harm tree trunks, for the simple reason that it does not twine and strangle branches as would bittersweet or the Fiveleaf Akebia, but it grows more or less vertically up the trunk. The lateral branches extend about three feet from the trunk or wall, and it is literally covered with 6"— 10" creamy white, flat flower clusters in June. Lonicera henryi Twining 8' Zone 4 Henry’s Honeysuckle The common Hall’s Honeysuckle, which has escaped cultivation in the South and become a pest over wide areas, is not reliably hardy in all parts of Massachu- setts. Henry’s Honeysuckle is similar in many respects to L. japoiiica halliana except that it is slightly more hardy. It can be used as a ground cover. Polygonum auberti Twining 20'— 30' Zone 4 Silver Fleece Vine A handsome, vigorous, twining vine that may grow as much as 20'-30' in a single season. The foliage is dense and bright green, and the small greenish white flower clusters appear in large numbers late in summer when few woody plants are in bloom. The fruits are not very effective. Its vigor and conspicuous late bloom are its chief assets in the garden. Wisteria floribunda macrobotrys Twining 24' Zone 4 Longcluster Japanese Wisteria This is a variety of the Japanese wisteria which is hardier than the more com- mon Chinese species, fi\ sinensis. This variety has flower clusters that are the longest of any, some in the Arnold Arboretum measured 36" long. In Japan, E. H. Wilson reported some flower clusters of this same species which were 52" long, but these of course, were growing under ideal conditions. Wisteria floribunda rosea Twining 24' Zone 4 Rose Japanese Wisteria This is the only wisteria with truly pink flowers, the racemes being at least 12" long and extremely fragrant. It is one of the best varieties of this species. GROUND COVERS Aegopodium podograria 12"— 14" Zone 4 Bishops Goutweed This sturdy perennial does very well in dry soil, and does almost equally well in sun and shade. Although the carrot-like fruiting heads may be as much as 14" tall, the foliage is considerably lower. It can be cut with a lawn mower and fully recover, although this is not conducive to good growth if done regularly. In some plants the leaves are green and in others the green leaves are bordered with white. It can become a weed unless it is kept restrained. Arctostaphylos uva-ursi Prostrate creeper Zone 2 Bearberry Only a few inches tall, this excellent native ground cover with its small (^"— f" long) leaves is especially adaptable for sandy soils. In fact it requires poor soil in which to grow. It is often used at the seashore in rocky areas where the small soil pockets may tend to dry out. In the wild, it forms dense mats which can be lifted in squares and transplanted to new locations. It is being used considerably along highway’s in eastern coastal regions for planting sandy banks where little else will grow. On the Pacific Coast it is equally popular and for the same reasons. Cytisus purpureus 1 8" Zone 5 Purple Broom The Purple Broom can be used as a ground cover, but it does not increase by runners or underground stems. In other words, the original plants should be spaced about 18"-24" apart and eventually they will grow together forming a complete covering never over 18" tall. Since all brooms prefer dry sandy soil, this has its merits, and the bright purple, pea-like flowers appearing in mid-May add to its effectiveness at that time. Diervilla lonicera 3' Zone 3 Dwarf Bush Honeysuckle A hardy native, this can be used as a coarse ground cover in part of the garden where its height is not objectionable. When well established it can be ruthlessly cut to the ground, and, since it does not sufler from any serious disease or insect pests there are places where it might be tried. It will increase by underground stems, but not rapidly. Euonymus fortune! kewensis Prostrate creeper Zone 5 Kew Wintercreeper Euonymus fortune! ni!n!ma ** Baby Wintercreeper Both these are very small-leaved ever^rreen forms, and they do differ in that minima has leaves about V' long and kexceusis has leaves smaller than this. It is probably inadvisable to plant these over lar^e areas, for they are small and slow growinor. In small spaces however, in the rockery or along the flagstones of the garden ])ath, they can cause much interest. Both hug the ground and seldom are over a few inches tall. Forsyth!a “Arnold Dwarf” Zone 5 'I'his dwarf forsythia, originated in the Arnold Arboretum and has never bloomed since it was introduced in 194-1. Hence it is not a desirable “flowering” shrub, but as a ground cover it is desirable where a mounded irregular growing mass is desired. Old plants are only ^1'-$' tall, usually almost twice as broad, and every- where the drooping branchlets touch the soil they root. Consequently, if planted several feet apart, the plants quickly cover the ground and of course, would keep the soil from washing. It does not make a uniform cover, since the habit of its growth results in high and low spots, but it can be depended upon to cover con- siderable ground in this interesting manner. Hypericum buckley! 10" Zone 5 Blue Ridge St. Johnswort A single plant of this species will cjuickl^v grow into a round mat of foliage sev- eral feet in diameter, and although the spreading branchlets do not seem to root, nevertheless they do cover the ground. The bright yellow flowers, about l" in diameter appear about mid- June, and the profuse small leaves give it a fine texture. Iberls sempervirens “White Gem” 6" Zone 5 var. of Evergreen Candytuft The old-fashioned Evergreen Candytuft has been considerably used in the past and its limitations are well known by most gardeners. This variety is more com- pact and dense than the species, hence is better for use as a true ground cover even though more plants must be planted at the start. There are other dwarf varieties available equally as good for ground cover purposes. Indigofera Incarnata alba 1^' Zone 5 White Chinese Indigo This white flowered variety is considerably hardier than the species and is not at all well known at present. The flowers are pea-like, appearing in July and the plant makes a dense growth by underground stems. Even if it does winterkill, it can be cut to the ground and quickly grows back in time to bloom profusely. This Japanese native has been in America over half a century without being used much as a ground cover. Ground Cover Demonstration Plots. This is situated on the Case Estates of the Arnold Arboretum, Wellesley St., Weston, and is always open to the public. At present there are over 125 different kinds of plants being grown as ground covers here. It is well worth careful inspection. Indigofera kirilowi 3' Zone 4 Kirilow Indigo A low, dense shrub which makes an excellent ground cover by suckering and spreading rapidly by underground stems. It grows to a uniform height and makes a more dense ground cover than does the Yellow-root. If, in severe winters, the branches are killed, it quickly sprouts from the base again and flowers in summer on the current years’ shoots. Juniperus horizontalis Zone 2 Creeping Juniper Juniperus horizontalis plumosa 12'' Zone 2 Andorra Juniper These are not rare by any manner of means, but they should be known by all who are interested in evergreen ground covers. The species is low and creeping, with runners several feet long, so that sometimes it does not cover the ground as well as should be expected. The variety plumosa on the other hand, is more dense and compact in habit, growing into a low, flat, slightly mounded plant. This vari- ety turns a pleasing purplish in the fall and remains that way a greater part of the winter. When it is used as a ground cover, if the plants are regularly spaced about 2' apart, they will eventually grow into each other and make a low dense mat completely covering the ground. It is commonly used as a specimen plant in many evergreen plantings, and should be considered for mass planting as a ground cover where a dense foliage mat is wanted. Juniperus chinensis sargenti 8"-12" Zone 4 Sargent Juniper This low, prostrate, creeping juniper has steel blue foliage and makes mats eventually 8'-10' in diameter. It makes an excellent ground cover with foliage a different color from the other junipers used for this same purpose. Leiophyllum buxifolium 1 8" Zone 5 Box Sandmyrtle A small evergreen of value as a ground cover only in very acid soil suitable for ericaceous plantings. It should always be planted in clumps about 12"-18" apart where it will grow into a rather loosely open evergreen cover, with waxy white flowers in May somewhat like those of blueberry, and a brownish green autumn color. It is not one of the best plants for completely covering the ground but can be used for variation where the soil is suitable. Leucothoe catesbaei 6' Zone 4 Drooping Leucothoe Although this is a 6' shrub in some areas, it can be used as a ground cover in Massachusetts if it is periodically cut to the ground every few years. It grows in clumps but does increase by underground stems to some extent, especially in sit- uations where rhododendrons grow well. The lustrous dark green leaves through- out the spring and summer turn a delightful bronze in the fall. In our area it does need some winter shade in order to prevent winter burning of the foliage. The small racemes of waxy white flowers appear in early June along the entire Pachistima cauhyi. This makes one of the best of everjfreen ground covers. under side of the gracefully arching branches. A native of southeastern United States, it can be used with discretion in Massachusetts, but only as a ground cover if it is kept periodically cut and even then it will grow as high as three feet. Lysimachia nummularia Prostrate creeper Zone 3 Moneywort This European native has escaped cultivation in America and so is frequently found in widely separated spots in the eastern United States. It withstands shade, but also does well in the sun, and prefers a rich, moist soil. The bright yellow flowers appear during the spring and summer and it grows rapidly as a creeping I vine along the soil surface, rooting at various places along its stems. If the soil 1 and situation are satisfactory this can make an excellent cover. | Pachistima canbyi Zone 5 Canby Pachistima This is a low evergreen with small leaves less than long which turn a beautiful bronze in the fall and winter. It makes one of the best of wintergreen S ground covers if planted in acid soil and given a little shade. It was this partic- j ular ground cover which looked the best of all in the Ground Cover Demonstra- tion Plots at Weston this past fall and early winter. | Pachysandra terminalis Zone 5 Japanese Spurge ' I This certainly is neither a new nor a rare ground cover, but it is without doubt j one of the best, especially for growing in the shade. It increases rapidly by 1 underground runners, is evergreen and can be grown in a wide variety of soils, but can not be expected to grow well in hot, dry situations in the full sun. It is this plant which might well be considered first in selecting a ground cover for j shadv situations. I i Rhus aromatica 3' Zone 3 Fragrant Sumac This is one of the taller ground covers but proves excellent in dry soils, and ^ for planting on sunny banks. To keep it in the ground cover category, this is another of the shrubs which might be periodically cut to the ground every three or four years. Its red fruits in early summer, and brilliant yellow and scarlet autumn color make it prominent. It increases rapidly by underground stems, but j because of its vigorous growth, its texture is definitely coarse when used to cover | the ground and so its use might be limited to the more rugged areas about the , home grounds. Rosa wichuraiana Prostrate vine Zone 5 Memorial Rose | Adapted for covering banks and rocky slopes, this procumbent trailer was first introduced into North America by the Arnold Arboretum in 1891, and was first used as a ground cover in Franklin Park, Boston. Its white flowers, appearing [16] Xanthorhiza simplicissima. This bed of Yellow-root has been growing by the ponds in the Arnold Arboretum since 188() and requires practically no attention of any kind. A fine native American plant which could be used more for ground purposes. in mid-July, are 2" in diameter and its lustrous green leaves are semi-evergreen. For rapid growth (it quickly roots along its stems where they touch moist ground), it can be considered as excellent for rough ground where finer textured and smaller ground covers might prove unsuitable. Teucrium chamaedrys 10" Zone 5 Chamaedrys Germander 'J'his makes a neat, uniformly high border or ground cover plant, but is not completely hardy in all parts of Massachusetts. Xanthorhiza simplicissima 2' Zone 4 Yellow-root A native American plant, found from New York to Florida, this makes an excellent woody ground cover. True, it grows 2' tall, but in a planting in the Arnold Arboretum we never have to give this planting any attention except to pull out woody weed plants which appear every few years. It increases rapidly by underground stolons and quickly makes a dense mat of upright stems and feathery foliage. The flowers and fruits are not especially prominent, the bark and roots are yellow. As a neat, uniformly high cover, this plant has no peers. Among the Best Common Vines Actinidia arguta Aristolochia durior Campsis radicans Celastrus orbiculata Celastrus scandens Clematis paniculata Clematis virginiana Euonymus fortunei Euonymus fortunei vegeta Hedera helix Lonicera japonica halliana Parthenocissus quinquefolia Parthenocissus quinquefolia engelmanni Parthenocissus quinquefolia saint-pauli Parthenocissus tricuspidata Parthenocissus tricuspidata lowi Parthenocissus tricuspidata veitchi Vitis coignetiae (kaempferi) Wisteria sinensis Wisteria sinensis alba Bower Actinidia 6, 7, 8, 9 Dutchman’s Pipe 1, 2, 4, 5, 6, 7, 9 Trumpet Vine 1, 2, 4, 6, 7, 8, 9 Oriental Bittersweet 1, 4, 5, 6, 7, 8, 9, 10 American Bittersweet 1, 2, 3, 5, 6, 7, 8, 9 ' Sweet Autumn Clematis 1, 2, 3, 4, 6, 7, 8, 9 Virgin's Bower 6, 7, 9 Wintercreeper 1, 2, 4, 6, 7, 8, 9 Bigleaf Wintercreeper 1, 2, 3, 4, 6, 7, 8, 9 g English Ivy 1, 2, 3, 4, 5, 6, 7, 8, 10 Hall's Honeysuckle 1, 2, 3, 4, 6, 7, 8, 9, 10 Virginia Creeper 1, 2, 3, 6, 7, 8 Engelmann Virginia Creeper 1, 4, 6, 7, 8, 9 St. Paul Virginia Creeper 6 Boston Ivy 1, 2, 3, 4, 7, 8 Low's Japanese Creeper 1, 2, 6, 7, 8 Veitch Japanese Creeper 1, 2, 6, 7, 9, 10 Glory Vine 6 Chinese Wisteria 1, 4, 6, 7, 8, 9 White Chinese Wisteria 1. 4, 6, 7, 8, 9 [18] Among the Best Common Ground Covers Ajuga reptans Calluna vulgaris Cerastostigma plumbaginoides Cerastium tomentosum Convallaria majalis Cotoneaster horizontalis Epimediura grandiflorum Gaultheria procumbens Gypsophila repens rosea Hosta sp. and var. Liriope spicata Lonicera japonica halliana Nepeta hederacea Parthenocissus quinquefolia Phlox subulata “Emerald Cushion" Polygonum reynoutria Rosa “Max Graf’ Rosa rugosa repens alba Sedum species Vaccinium angustifolium laevifolium Vinca minor Carpet Bugle 1, 2, 4, 6, 7, 8 Heather 4, (>, 7, 8, 10 Blue Cerartostigma 6, 7, 8 Snow-in Summer 2, 6, 7, 8 Lily-of-the-Valley 1. 2, 4, 6, 7, 8 Rock Spray 1, 2, 3, 4. 5, 6, 7, 8, 9, 10 Longspur Epimedium 1, 8 Checkerberry or W intergreen 4, 6, 8, 10 Rosy Creeping Gypsophila (Baby's Breath) 1, 2, 4, 6, 8 Plantain-lily 2, 3, 4, 5, 6, 7, 8 Creeping Liriope (Lilyturf) 5, 6, 10 Hall's Honeysuckle 1, 2, 3, 6, 7, 8, 9, 10 Ground Ivy (Gill-over-the-Ground) 6, 7 Virginia Creeper 1, 2, 3. 6, 7. 8 Var. of Moss Pink 1, 2, 6, 8 2, 6 2, 6, 7, 8 Var. of Rugosa Rose (>, 7, 8 Stonecrop 1. 2, 4, 6 Lowbush Blueberry 4, 6, 8 Periwinkle or Myrtle 1, 2, 3. 4, 5, G, 7, 8. 9, 10 Note: All these vines can be observed growing in the Arnold Arboretum with the exception of two clematis which are in our nurseries and yet too small to be planted out in the collections. All the ground covers mentioned and some eighty more can be seen in the Ground Cover Demonstration Plots which are on the Case Estates of the Arnold Arboretum, on Welleslet’ Street in Weston. Here each plot is kept 6' x 6' so that over 125 different ground covers can be compared as to their habit of growth, height, foliage cover and general all around suitability as ground covers. There is no collection of ground covers as complete as this anywhere in the United States. All the plants are clearly labeled, and, to anyone interested in studying this serviceable group of plants, a visit to this collection would be worth the trip to Weston. [ 19] Donald Wyman NEW LECTURE FOR GARDEN CLUBS “The Arnold Arboretum — America’s Greatest Garden” 'riiis lecture is a series of 100 Kodaclirome slides showinjr the best that is growing in the Arnold Arboretum, and is available to garden clubs for the small rental fee of five dollars. As the slide collection in the Arboretum has grown, it has become possible to assimilate this lecture for the use of any garden club or interested group that wants it. Accompanying the slides is a typed list showing just what is portrayed in each picture. Also included is a 46 page book- let which gives some of the background and early history of the Arboretum, to- gether with a general account of its many accomplishments up to the present time. Since small kodachrome slides are universally used now, most people know that they are best shown in a completely darkened room, using a glass beaded screen. Small 100 watt projectors can be used when the image is small but for large groups, air-cooled lanterns (SOO-IOOO watts) are highly superior and result in bringing out all the colors to best advantage on the screen. Any individual who spends a little time studying the booklet, together with the notations about each slide (both common and scientific names of the plants are listed) would not have much difficulty in presenting this Arboretum story to a group. The nominal rental fee is five dollars. It is hoped, that groups interested in the Arnold Arboretum and the thousands of plants growing there will avail themselves of this opportunity and so bring the Arboretum before many who can not visit it. Arnoldia Renewals If you have not done so, now is the time to renew your subscription to Arnoldia for 1953. The check for $1.00 should be made out to Harvard University, and sent to Arnoldia,” Arnold Arboretum, Jamaica Plain 30, Mass. ARNOLDIA Gray Herbarium Harvard University MAE t953^ A continuation of the Bui.letin of Popular Information of the Arnold Arboretum, Harvard University Volume 13 MARCH 20, 1953 Number 3 PRUNING ORNAMENTAL SHRUBS AND TREES The exhibit of pruning at the 1953 Boston Spring Flower Show was assem- bled by the Arnold Arboretum for the purpose of clearly showing right and wrong methods of pruning. A little knowledge of what to prune and how to do it, goes a very long way in assisting plants to grow into well balanced specimens which prove an asset in any garden. Conversefv, the indiscriminate hacking of shrubs and trees at definite heights is the quickest means by which otherwise beautiful plantings are made unsightly. A glance through this exhibit showed some of the following things : WHEN TO PRUNE As far as the growth of the plant is concerned, pruning can be done almost any time except in the early summer, but if done then, the new growth may not have sufficient time to mature before winter and killing may result. However, as far as our interest in the ornamental qualities of plants is concerned, shrubs are divided into two groups, those that bloom in the early spring like Daphne, For- sythia and Lilac, which might be pruned after they flower in order to obtain the full benefit of their flower the current year; and secondly, plants which bloom on the current year’s wood like Hydrangea and Rose of Sharon which can be pruned in the late winter or earfv spring and still be expected to bloom the same year. Trees are usually pruned in the late winter and early spring (with the ex- ception of those that “bleed” profusely like the Birch, Maple, Yellow-wood) for at this time, before the leaves appear, it is much easier to see which branches should be removed, and also it gives the tree the entire spring and summer to form new growth. However, they can be pruned anv time excei)t the “bleeders” as noted above. WHAT TO PRUNE 1 . Dead, broken or diseased branches. 2. Broken roots and one-third of the branches at transplanting time. Some roots are always cut when a ])lant is dug. A good general rule is to remove about [ ->i ] one third of the total linear branch len inches in diameter, and a pale 'File “Yodo'fawa” azalea (A*, yedoensls) . 'Phis double-flowered azalea was found as a cultivated plant in Korea and named about twenty years before the sinfyle-Howered H. yedoense poukhaiiense, was discovered. This results in the rather uniipie situation of the double-Howered plant bearinj? the specific name and the single-flowered form beinf*’ the variety. to rosy |)iiik. Apparently perfectly hardy under New Kn ] I PLATE IX. bruits of ornamental woody plant fi,’enerathe seeds of which should be cleaned before shippiiif*'. Viburnum; ^2, Euonymus; S, Cornus; t, Cotoneaster; o, Malus; 6, Berberis; 7, Madura; 8, Ginkj^o; 9, Sorbus, 10, Ilex; 11, Taxus; 12, Rosa. Anielanchier oblongifolia Cornus alba I’runus sarjrenti Lonicera morrowi Amelanchier spicata Cornus stolonifera Lonicera altmanni Lonicera bella Lonicera chrysantha Lonicera maximowiczi Morus sp. Rosa agrestis Rosa hugonis Rosa roxburghi Amelanchier amabilis Amelanchier sanguinea Populus maximowiczi Ilex geniculata Lonicera alpigena Frinsepia sp. Prunus japonica Prunus glandulosa Prunus maritima Acer ginnala Cedrus libani Ceanothus pallidus roseus Cornus racemosa Crataegus arnoldiana Cytisus nigricans Berberis laxiflora Betula papyrifera Carpinus sp. Cornus baileyi Khretia thyrsiflora Berberis fendleri Berberis heteropoda Caragana maximowicziana Cornus mas June ^0 Prunus subhirtella Prunus tomentosa Viburnum fragrans June .SO Prunus cerasus July 5 Lonicera muendeniensis Lonicera notha Lonicera tatarica Lonicera xylosteurn Mahonia aquifolium Nemopanthus mucronatus July 20 Rosa spinosissima Vaccinium vitis-idaea Viburnum tomentosum July so Rosa ecae Vaccinium corymbosum August 5 Rhamnus frangula Rhus typhina Ribes odoratum Rosa amblyotis Rosa harisoni Rosa primula August 15 Cytisus purpureus Gaylussacia sp. Lonicera webbiana Ostrya virginiana Shepherdia argentea Viburnum sieboldi August 20 Kolkwitzia amabilis Prunus cerasifera Spiraea veitchi Viburnum alnifolium \Jburnum lantana August SO Cornus kousa Cotinus coggygria Cotoneaster racemiflora Laburnum sp. [44] Lonicera demissa Rosa macouni Lonicera orientalis Rosa pendulina Lonicera tangutica Sambucus canadensis Rosa Carolina Syringa amurensis Rosa davurica Viburnum trilobum September 5 Acer negundo Potentilla fruticosa Berberis vernae Rhus copallina Cladrastis sp. Rosa rugosa Cornus asperifolia Rosa reversa Cornus glabrata Crataegus punctata Zanthoxylum americanum September 13 Acer griseum Lindera benzoin Acer pensylvanicum Lonicera subsessilis Aesculus sp. Paeonia suffruticosa Akebia quinata Philadelphus virginalis Aronia melanocarpa Rosa acicularis Betula lutea Rosa alba Betula lenta Rosa blanda Betula populifolia Rosa coriifolia Betula pendula Rosa rubrifolia Chionanthus sp. Rosa willmottiae Clethra alnifolia Rosa wood si Cyrilla racemidora Sassafras sp. Deutzia sp. Schisandra chinensis Evodia danielli Viburnum wrighti September 20 Acer platanoides Cotoneaster rosea Acer saccharum Cotoneaster tenuipes Aralia spinosa Fagus sp. Berberis henryana Halesia sp. Berberis poireti Ilex yunnanensis Corylopsis sp. Kalopanax pictus Cotoneaster adpressa Nyssa sylvatica Cotoneaster ambigua Pieris sp. Cotoneaster melanocarpa Quercus sp. Cotoneaster moupinensis Viburnum dilatatum Cotoneaster nitens September 30 Actinidia arguta Koelreuteria paniculata Ailanthus altissima Lonicera iberica Cercis canadensis Pinus sp. Clerodendron trichotomum Rosa gallica Cornus sanguinea Symplocos paniculata F.xochorda sp. October 5 Ampelopsis sp. Berberis amurensis [45] Berberis bretscliiieidcri Cormis riorida Cotoneaster foveolata Fotlier^illa sp. Haniarnelis sp. Larix sp. Maijfiiolia acutiiiiiata Magnolia soulangeana Magnolia stellata llobinia sp. Acanthopanax sp. .\ronia arbutifolia Aronia prunifolia Celastrus sp. Cotoneaster acutifolia Cotoneaster bullata Cotoneaster dielsiana Cotoneaster divaricata Cotoneaster lucida Abies sp. Berberis chinensis Berberis gilgiana Caragana arborescens Castanea mollissima Celtis occidentalis Chaenomeles lagenaria Clematis paniculata Corylus americana Corylus avellana Corylus cornuta Davidia involucrata Euonymus alata Pmonymus americana pAionymus bungeana KiUonymus fortunei vegeta Euonymus nikoensis Euonymus obovata Euonymus sanguinea Fraxinus sp. Ginkgo biloba Albizzia julibrissin rosea Alnus glutinosa Berberis vulgaris Buddleia sp. Cercidiphyllum japonicum Crataegus oxyacantha Solan urn dulcamara Sorbaronia jacki Sorbus sp. N'accinium oldliami N'iburnum betulif'oliurn Viburnum carlesi \’iburnum cassinoides \dburnum dentatum Viburnum ovatifolium \dburnum prunifolium October 10 Cotoneaster zabeli Enkianthus sp. Euonymus bulgarica Hydrangea petiolaris Lonicera ferdinandi Pseudotsuga taxifolia Symphoricarpos sp. Faxus sp. Tsuga sp. October 1 5 Hicoria sp. Ilex verticillata Juglans sp. Juniperus sp. Leucothoe catesbaei Liriodendron sp. Picea sp. Rhododendron sp. Rosa canina Rosa corymbifera Rosa eglanteria Rosa helenae Rosa hibernica Rosa horrida Stewartia sp. Thuja occidentalis Tilia sp. Llmus parvifolia Viburnum acerifolium Viburnum setigerum Vitis sp. October 20 Lycium sp. Malus baccata Malus toringoides Oxydendrum arboreum Phellodendron sp. Photinia villosa Physocarpus sp. Viburnum hupehense Berberis koreana Cotoneaster horizontalis Cotoneaster integerrima Cotoneaster tomentosa Gymnocladus dioica Gleditsia sp. Hippophae rhamnoides Ilex opaca Baccharis halimifolia Berberis aggregata Berberis canadensis Callicarpa sp. Cotoneaster multiflora Elaeagnus angustifolia Berberis thunbergi Cotoneaster affinis Elaeagnus umbellata Franklinia alatamaha Lonicera bracteolaris Lonicera henryi Crataegus lavallei Crataegus nitida Cotoneaster rugosa Cotoneaster salicifolia V^iburnum lentago October 30 Kalmia latifolia Ligustrum sp. Malus, many sp. Pseudolarix amabilis Rosa arvensis Rosa virginiana Viburnum burkwoodi Wisteria sp. November 5 Myrica pensylvanica Paulownia tomentosa Rhodotypos scandens Viburnum lobophyllum Viburnum opulus Viburnum sargenti November 15 Lonicera korolkowi Lonicera maacki Pyracantha coccinea Ribes fasciculatum Rosa setigera Rosa wichuraiana November 20 Crataegus prunifolia Rosa multiflora November 30 Crataegus phaenopyrum Ilex glabra Cleaning Seeds Most seeds must be cleaned in one way or another before they are sown. The fruits of rosaceous plants, viburnums, magnolias, dogwoods and many other fruits with pulp about the seeds must be cleaned before the seed is shipped or even before it is stored in large quantities, for the rotting pulp quickly heats and in many 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 frequently picked while it is still slightly green on the tree, or picked up from the ground while it is damp, and if stored or shipped in large quantities before it is thoroughly dry, it may heat and be completel.v killed on arrival. This has happened to many shipments arriving at the Arboretum. 7'here are many ingenious methods for cleaning seeds, some of them worked out on the spur of the moment. Cones from coniferous trees, for instance, must l)e dried and in many cases have i)ot air applied to them in order that they will open aiul thus allow the seeds to fall out. For small amounts, this is easily accom- plished in the hot sun or on the <» ] treated with a mild disinfectant, such as a 5-10 per cent solution of potassium permangenate, then dried and bagged for shipment. It will be noted in the following lists that some seeds should not be allowed to dry out in transit (List A). This is a most important group of seeds and it is safe to say that we have been unable to germinate hundreds of groups of seeds sent us here, merely because the collectors failed to recognize the importance of this 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 kept all his seeds until he was finally read}' to send them in one shipment. As a re- sult, 45 per cent of the seed numbers he had sent (l59 packets in all) failed to germinate, a discouragingly large amount when one considers the efforts he spent at his end to collect them and the efforts to which we went here to record and sow them. 4'he old fashioned method in shipping seeds, used frecpiently by E.H. Wilson so they would not dry out in transit, was to pack them in charcoal. Moist saw dust or moist peat moss is not good if the shipping period is long or hot, for the seeds may either start to germinate, or high temperatures may cause the packing materials to heat and kill the seeds. Charcoal, however, proved an excellent medium for it does not absorb moisture. Polythene bags can now be used to excellent advantage. This material is widely used 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, and plants 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 1 : Nos. 7-8, Oct. '26, 195l). Bags made of polythene should be tightly sealed, could contain several paper packets of seeds and even a very small amount of moistened moss to keep the small amount of air in the bags slightly humid, for those seeds that shouhl not dry out. Another method for shipping such seeds as acorns or chestnuts would be to dip them in paraffin. We have sent seeds treated this way successfully to Norway, Ital.v and Palestine 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 {)lant from which collected. 2. Date collected. .8. 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 tlie United States prohibit the entry of some seeds into this country. None can be sent in with moist pulp about them. In tlie northern part of the United States the more important woody plants the seeds of which are prohibited are Berberis sj)ecies, Uibes nigrum. Bamboos and their relatives. I'liese same (|uarantine laws approve only certain paekinj^ materials such as peat moss, sphagnum, excelsior, wood shavinj^s, sawdust, jjround cork, buck- wheat hulls, expanded vermiculite and charcoal. I’ackinjx materials prohibited are soil, sand, leaves, forest litter, wood's moss, hay, straw, etc. — anythinjr taken from direct contact with the soil. Seeds packed in such materials will be prohibited entry. .Seeds collected in the United States for the Arnold Arboretum should be sent to ; 'The Horticulturist Arnold Arboretum, Harvard University Jamaica Plain JO, Massachusetts, U.S..-\. Seeds of woody plants collected in foreig^n countries and destined for recipients in the United States fiiu.sl be accompanied hij a permit. I'he Bureau of Kntornology and 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 number appears on a standard green and yellow tag bearing the address of the cjuarantine station ( Hoboken, X.J. ; Miami, Florida; Laredo, 'Pexas ; or San Francisco, Cali- fornia). This required tag is the only address appearing on the outside of the package other than the collector's name and address in the upper left hand cor- ner. The Arnold Arboretum's permit number is 37-17 38, and collectors in foreign countries should request these permits from the Arboretum in advance of seed collecting and for the port of entry most convenient. ^ ‘Seeds for Experimental Purposes only — no commercial value” should be clearly written on the oul.side of the package from a foreign country. Inside the package should be the address of the Arboretum and a list of the seeds enclosed. These regulations are required by the “Plant (Quarantine Act if37” and should be followed to insure foreign seeds reaching their proper destination in the United States. A 10 per cent DDT dust might be mixed with the seeds to kill insects. 'Phe following three lists do not contain all those wood.v plants commonly grown from seed but they should serve as a guide to collectors to indicate how certain seeds 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 for periods longer than one year. Fhe 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. '■Z. 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. J b. Label all seed packets completely. | 6. Ship as soon as j^icked (and by air) those in List ‘A.'' | PLATE XI. Fruits of ornamental woody plant f^enera recpiirinf? no cleaniiif? before shippin^r. , Hobinia; ‘2, Koelreuteria; 3, Wisteria; f, Cytisus; 5, Fraxinus; <>, Fotherg^illa; 7. Evodia; S, Juniperus; 9, Kolkwitzia; 0, Syriiifi^a; 11, Rhododendron; ll2, Tilia; 18, Hypericum; 14, Catalpa; 1.5, Tsuffa; Hi, Finns; 17, Clematis; IH, Flatanus; 19, Ailanthus; 20, Gymnocladus; 21. Picea; 22, Cladrastis; 28, Philadelphus; 24, Gleditsia; 2.5, Abies; 20, Thuja. 7. Send the remainder of the shipment as soon as possible, keeping the seeds dry 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 distances only by air and should be sown as soon as received. Special precautions should be taken in packaging these for shipment so that they will not dry out enroute, otherwise, they may be worthless on arrival at their destination. Some will remain viable only a few days (Salix); others a few weeks to six months (Cedrus). Acer Davidia Os try a Aesculus Diospyros Populus Alnus Fagus Fotentilla Amelanchier Franklinia Quercus Ampelopsis Halesia Rhus Aralia Juglans Salix Asimina Liriodendron Sassafras Carpinus Lind era Shepherdia Cary a Liquidambar Sophora Castanea Lycium Spiraea Cedrus Magnolia Staphylea Cercidiphyllum Mahonia Stewartia Chamaecyparis lawsoniana Myrica Sty rax Clerodendron Nandina Ulmus Cryptoraeria Nyssa Zelkova B. Seeds that can be sown or stratified as soon as ripe or dried and sown the following spring (These need not necessarily be shipped quickly by air, but can be sown or stratified as soon as received from the collectors.) Berberis Cotoneaster Lonicera Betula Crataegus Malus Buxus Elaeagnus Phellodendron Caragana Exochorda Prunus Celastrus Ginkgo Pyracantha Celtis Gleditsia Rhodotypos Chaenomeles Hippophae Robinia Chionanthus Ilex Tax us Cladrastis Juniperus Viburnum Cornus Ligustrum 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, but this group can be held the longest and does not deteriorate as rapidly in shipment as seeds in List “A.’*) Actinidia A triplex Chamaecyparis Akebia Callicarpa Cupressus Ailanthus Calycanthus Cytisus Albizzia Caryopteris Elaeagnus Amorpha Catalpa Deutzia Aronia Cercis Diervilla [ .54 ] Kuonymus Morus Rosa Evodia Paulownia Sciadopitys Fraxinus Philadelphus Sophora Hibiscus Physocarpus Sorbus Kalmia Picea Symphoricarpos Koelreuteria Pinus Syringa Laburnum Platan us Taxodium Lagerstroemia Pseudotsuga Thuja Larix Pyrus Tsuga Leucothoe Rhododendron Vaccinium Libocedrus Ribes Vitex Metasequoia Robinia Wisteria Longevity The longevity of ornamental woody plant seeds has not been given exhaustive study. The United States Department of Agriculture reviewed the literature on this subject in its “Woody Plant Seed Manual” Misc. Pub. No. 654, issued June 1948, and for detailed information the reader is directed to this publication and 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 variable factors. Poplar seeds lose their viability very fast and must be sown within a few weeks of ripening — willow seeds are viable even a shorter time. E,xperimentation I has shown that many annual garden flower seeds are viable under normal condi- I tions for 2-3 years and many 4—5 years. Many vegetable seeds are good up to I 10 years (beets, cucumber, radish), many of the cereals from 2-15 years, and I certain weed seeds like smartweed, moth mullein and evening primrose germi- I nate after having been stored in inverted bottles in the soil fifty years. The re- I cent classic example of Lotus seeds which have proved to be 1000 years old and germinated is the extreme. I Experiments in dormancy and the keeping qualities of seeds have shown that I longevity usually increases with a drop in the temperature of the stored seeds, so ' that now it is generally believed that temperatures of 32°-41° F are ideal for h seed storage, especially when the moisture content of the seeds can be maintained j uniformly. Many commercial nurseries have mechanical refrigeration equipment now 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 satisfactorily stored for a year or two in open containers at room temperatures, by far the i greater proportion can be kept longer if stored in air tight containers at tempera- tures between 32°-41° F. There are numerous problems connected with the breaking of the dormancy of the seeds of ornamental woody plants and accurate information on their lon- gevity is meagre. Most of the following listed information has been taken from the “Woodv Plant Seed Manual” but some has l)een inserted as a result of the [ •>•> ] experience with tliese seeds we have g^rown at the Arnold Arboretum. Here is j. recorded the approximate time durin«: which woody plant seeds can be stored li (not sown or stratified) and still retain some viability. Naturally, the longer the = storage jieriod the less the viability in most cases. The column on the left indicates the time in years that seeds can be stored [I normally (dry and at room temperatures) and still be viable. The column on the ; right indicates the time in years that the seeds can retain some viability when stored (not sown or stratified) in air tight containers at approximate tempera- tures of F. It should be pointed out that those plants in List “A” page 54* do not appear here merely because it is a known fact that they must be sown (juickly after they mature and before they dry out. This following list is most incomplete and if nothing else, it serves to point out the fact of what little we know about the longevity of these seeds and in some cases, how really short lived they appear to be. Longevity of Seed in Storage (All those in list “A" page 54 have very short longevity at room temperatures) Ordinary storage Sealed storage 3 2° -41° F {in years) {in years) Abelia 1 Abies alba less than 1 .3-4 balsamea 1-2 concolor ft ft 3-4 grandis 1 1 procera 3 Acer ginnala 2^ macrophyllum sow at once — can ’t be stored negundo l4 pensylvanicum platanoides 1 pseudoplatanus \-^Z 2 + rubrum 1 saccharinum 1 saccharum 1 + spicatum o Actinidia 1 + Akebia 3 Ailanthus altissima 1 + Albizzia julibrissin 3 Alnus glutinosa li Amelanchier 1 Amorpha fruticosa 3-3 Aronia 1 Atriplex sp. 6-7 Baccharis 6 mos. [ 5(i ] Berberis 1 Betula lenta lutea nigra papyrifera pendula populifolia Buddleia 1 Buxus 2 Callicarpa 1 Caragana arborescens 5 Carya sp. Catalpa bignonioides 2 speciosa 2 Ceanothus americanus Celastrus Celtis laevigata 3 occidentalis Cephalanthus occidentalis Cercis 1 Cerocarpus montanus 5 Chaenomeles Chamaecyparis 1 Chionanthus virginicus 1 Cladrastis 2 Clematis 1 Clethra Comptonia peregrina Cornus florida 2 racemosa 2 Corylopsis Corylus americana avellana 1 cornuta Cotinus 1 Cotoneaster Crataegus mollis 1-2 Cupressus arizonica Cyrilla 1 Cytisus 1 Davidia Elaeagnus angustifolia 8 commutata 1-2 Deutzia 1 Diervilla 1 Epigaea repens 8 mos 12 2 2 2 8-5 2 1 + 4 1 2 2 2 + 1 2 + 2 + 2 + 2 + 8-10 8 4 [.37] Krjkiaiitlius Kiioiiy rmis atrojxjrpiirea eiiropaeiis verrucosus Kvodia Kxocliorcia Fatrus ‘jraiidifolia sylvatica Fotliergilla Fraxinus excelsior nijjra oregana pennsylvanica americana clipetala Gaultheria procumbens Gaylussacia baccata Ginkgo Gleditsia Gymnocladus dioicus Hamamelis virginiana Hippophae rharanoides Hydrangea Hypericum Ilex Juglans cinerea Juniperus ashei pachypoda scopuloruin Kalmia Koelreuteria paniculata Laburnum Larix decidua laricina sibirica Leucothoe Libocedrus decurrens Ligustrum vulgare Liquidambar styraciflua Lonicera tatarica Madura pomifera Malus pumila Metasequoia Morus alba Myrica cerifera Paeonia suflPruticosa I o o o 1 I I 1 1 ^2-s 1 f- 3 1 8 4 2 o 1 o 2 1-2 2 + o i-i 4-.') 4 .5 si 2 + 10 1 3-4 3-4 -p () 1 -4 - 2 1 ^ 3 1-2 1 — 2 2 + o 3 1-2 [ -58 ] Parthenocissus 2 + I’aulownia 1 Fhellodendron o Pliiladelphus o Ph^'socarpus 1 Picea 10+( abies 5 -j- engelmanni 5 — glauca 10^ mariana 5 “T rubens 10-f Pieris 1 Pinus attenuata 1 5 (on trees) 10 + banksiana <3 + caribaea 9 contorta latifolia 30+ (on trees) 7 + coulteri 2-4- densidora 1 + echinata 7-9 dexilis (3 halepensis 2 + jedre.vi 3 10 + lambertiana 10 + monticola 2 mu go 1-2 muricata 20+ (on trees) nigra 2 + palustris 2 + 5—9 pinaster 3-4 ponderosa 6 pungens 9+ (on trees) resinosa 3—0 10 + rigida 2 + strobus 8 + sylvestris 13 taeda 7-9 thunbergi 1 + virginiana 5 + Prinsepia 1 Prunus americana 4 armeniaca 1-2 avium 1-2 pensylvaniea 1 + serotina 2 virginiana 1 Pseudotsuga macrocarya 4 4 taxifolia 10 4 Ptelea trifoliata 1 + Pyracantha 1 Pyrus communis 2-3 (^uercus robur Khaiinuis a) ni folia (lavurica catliartica Khodotleiulroii Khodotypos scandens Khus jjlabra typliina Kibes ainericanum c.vnosbati Kobinia pseudoacacia Kosa Rosa blanda Kubiis idaeus occidentalis Sambucus canadensis pubens Sapindus drummondi Sequoia sempervirens Sequoiadendron giganteum Shepherdia argentea Sorbus americana aucuparia Symphoricarpos albus Syringa vulgaris Taxodium distichum Taxus baccata Thuja occidentalis plicata Tilia americana cordata Tsuga canadensis heterophylla LTmus americana pumila Vaccinium Viburnun^ acerifolium cassinoides lentago opulus trilobum Vitex agnus-castus \dtis riparia Wisteria Zanthoxylum americanum Zelkova 3-1- M t) mos 0 b mos 1 3-4 10 — 3—0 when stratified 3-4 1-^2 1-2 o 0 4 1 8-24 3^ 8 2 4 1-2 b mos 6 mos 4 4^ 5 2 o 2-r 4 2 1-4- 4' 4+ 1 o 2-i Donald Wyman [ «« ] ARNOLDIA Gray Herbarium Harvard University SEP 2, 19533 E I A continuation of the \ Hulletin of Popular Inpormation \ of the Arnold Arboretum, Harvard University i ^ ^ t \ oLUME IS SLlMPvMBF.R ‘25, 1953 Number 10 I NEW METHODS IN PLANT PROPAGATION The majority of horticultural varieties of ornamental trees and shrubs must be grown by vegetative propagation for the reason that they do not develop ■ true from seeds. However, they can be propagated by grafting or budding on ^ seedling or clonal rootstocks, by stem or root cuttings and by soil or air layering. All of these procedures have the flavor of great antiquity. Grafting of trees of ! merit on seedling rootstocks was known in the Roman period while air layering i was performed by the Chinese thousands of years ago. Moreover, far back in time I horticulturists used distinct methods of encouraging root formation of cuttings. I riiey often placed a sprouting seed in a cleft made at the base of the cutting thus I providing the added hormone which stimulates root growth. Bottom heat for * propagating beds was provided by filling a trench with fresh horse manure covered I with soil. The decomposition of the manure provided the necessary heat. The Chinese kept their air layers moist by water dripping from an earthen vessel sus- i pended above a split clay pot containing moss circling the branch, j Pile modern propagator now has many new techniques which make productivity higher and his work easier. Synthetic hormones, such as indoleacetic and indo- lebutyric acid, stimulate root formation in cuttings and air layers. Generally, hormones are applied to the cut surface of the cutting either in liquid or powdered form. I’hey are made up in various strengths, for what is practical for one species may be impractical for another. Each plant has a unique combination of charac- teristics, even in the relationship within the species, so that it is impractical to advocate the exact hormone one must use, for plants are complex and may differ from place to place. Bottom heat in cutting frames is now provided by electric heating cables that has a significant value for many cuttings. High humidity needed for softwood cuttings was formerly provided by glass enclosed cases and recently supplemented by automatic mist spra\*ers. Polyethylene film is now used to maintain high hu- [ « ] I 1 ! I ^ \a man to use. So it is with the compounds for controlling plant diseases; ferbam is useful as a preventive spray for many fungus diseases, certain other diseases are controlled best by some of the mercuric compounds. We now have over four thousand spray formulations to choose from ; some are multi-purpose while others serve only one pur{)ose; none are all-purpose. A distinct advantage in using DD'I', lindane, dieldrin, and some of the other new spray materials, is their residual action; however, this does not eliminate the need for the proper timing of spray applications. DD'J', especially if ti e emulsifiable form is used, may be effective for a month to six weeks after appli- cation. Lindane not only has a residual effect, but also will kill some insects in- side of tree leaves such as young birch leaf miners when they are in the leaves. One of the advantages of dieldrin is its long residual action. Although this re- sidual action helps us in some cases, we must still time our sprays correctly, not only to get the most benefit from the chemicals used, but also to be able to pro- tect all of the plant, especially in the growing season when growth produces new, and unusually tender, areas for the plant pest to attack. It is especially important in disease control to protect these expanding surfaces since we still must rely mainly on preventing the entrance of the disease organism into the plant tissues to control plant diseases by spraying. For this reason, disease con- trol spray applications must be repeated every week or two in the spring. The chemistry of these newer organic spray materials is rather complicated for the layman. It would be difficult for most of us to remember the chemical name or make up of these substances so the manufacturers and others concerned have adopted standard or generic names for many. In this manner the chemical: 1, 2, 3, 4, 5, 6, 7, 8, 8 octachloro -4,7-methano -3a, 4, 7, 7a-tetrahydroindane has become chlordane ; the gamma isomer of benzene hexachloride of at least 99% purity has become lindane. The names: parathion, ferbam, malathon, and many others have each come to mean a definite substance so that we may rely on them. A few of the first materials still keep their initial names as DDT, or TEPP. Any one of these substances may be available on the market in various forms and may be sold under brand names. For example, lindane is commonly available as a 'ib^o lindane wettable powder or a 20% lindane emulsifiable concentrate. Anyone handling spray materials must remember that they are our ammunition, used in most cases, to kill the pests of our plants. Most of them are poisonous in one way or another. They must be handled with care to protect the user and the public; but, by choosing the correct compound and applying it properly, we can push forward the battle-line in our never-ending war on injurious insects and plant diseases. Paralleling this development of new materials, there has been the development of mist spraying where low volumes containing relative!}’ high concentrations of spray material are carried to the plant by an air stream. This method of spray- ing has its limitations, but when feasible, it has given excellent results especially [70] in control of leaf-eating insects, at greatly reduced operating costs. The problem of spray application with these new machines is important in that the right amount must be applied to the plant in the correct manner. With mist spray methods, the amount of material which is applied to a tree is set by the size of the mist particles, concentration used and the amount (i.e the length of time) the tree is sprayed. With the hydraulic spray formulae, the amount of material applied is governed by the spray concentration and the amount which will stay on the plant without running off. Inasmuch as any excess applied with a hydraulic sprayer will merely run off without harming the plant, this is probably the safer spraying method. The Arnold Arboretum Spray Schedule With over 6000 kinds of woody plants growing in close proximity in the Arnold Arboretum, it is no wonder that the problem of keeping all these plants free of pests is acute. In the old days, it seems, this was a fairly simple procedure, but now, with all the many insects and disease pests which abound, and with the hundreds of remedies offered by various commercial chemical producers to combat these pests, pest control here has become complicated indeed. Only a few years ago, we would merely spray for scale insects, canker worms, the larch case bearer and the elm leaf beetle. Admittedly some of the collections may have been infested with disease or insect pests, but they did not seem serious at the time. This year, the grounds force had to spra}" on 24 different days, from April 1 to September 29, and each time the spraying was necessary to control some pest or disease that was disfiguring some of the specimens here on the grounds. However, because of this extensive spray program, the plants in the Arboretum have been growing vigorously and the results of disease and insect depredations are hard to find. Most of our spraying is considered to be on an experimental basis, since we find it expedient to change our sprays from time to time as new and possibly better ones become available. However, it was thought that readers of ArnokUa and others interested in the Arnold Arboretum would be interested in knowing ex- actly what we have used in our spray program this year. We offer it here, merely as a guide to those who are interested in similar problems, but with emphasis on the fact that these control methods are definitely not the only ones, nor are they possibly the ^^best” ones. Everyone familiar with pest control knows that there are frequently several effective controls for one pest, as well as manj- different kinds of chemicals which can be used, some basically the same but with different trade names. The Arnold Arboretum does not take any credit for the formulae here pre- sented as pest controls, since the best recommendations are scanned from the various experimental stations (and modified, if we think necessary) to suit our particular conditions. Consequently our program should be considered as experi- [71 ] mental only, but, it is only fair to add, it resulted in pest free plants diirinf; the {Trowing: season of 19.53. A few years ag^o, before the advent of DDd', all the spraying here was done with the old-fashioned hydraulic sprayer. Then, when newer materials became available and mist spraying appeared , we tried to do a major part of the spraying with a large mist blower, since it obviously cost less to operate such a machine, when two men do the work instead of five or six. However, more recently, we have come to the conclusion that there is a very definite place for both types of spraying, when com])lete coverage and pest control is the main need, for certain sprays can be more effectively applied by the mist blower, and others need to be applied by the hydraulic high pressure sprayer in order to give effective coverage. In order to make the following chart usable for individuals who may not have a mist blower, we have included a column for the equivalent spray to be used in the hydraulic sprayer. VVe have used all the mist sprays and most of the hydraulic sprays, but a few of these latter have been added untried, but taken from relia- ble sources. The dates of application vary some from year to year, even in the Arboretum. Insect and disease pests should be hit when they are most vulnerable, and no hard and fast dates can be given for this. It is always best to know exactly what the spray is expected to control, and find whether the pest is in the desired form before the spray is applied. Too often spraying is done about the home grounds merely because some one else has done it or it is **about” time the plants were attended to. To be truly effective, the application must be timed properly. [72] ARNOLD ARBORETUM SPRAY SCHEDULE 42 O >> _ 03 c a c/) cfl K a 3 W_. '^’c3 >. iao ' c ;z; ^ W) "cfl -i CU ^ O CT3 03 03 3 > >>x: CJ WttHC/)U u 03 ^-T CO C 'O I-S ^ ^ c |o| CJ O). 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Jr C qj y o c Jr ^-p 03 y p X 2 ^ X c n3 O U. > X y y a; 2 E y y 23 8 ^ X y 03 ^X X •-I ra £ coS X 2 i2 o "E, P S X y qj X ^ — o LO £ .-( a!M 2 y 15 ^ S ^^2 «S-|2 fsll O) ’-' C7 U C y ,-H y O 2 X ■ 3 P X X 3 X c ax * q> 1h CO o o J £ 03 y :> y r- ^ X qj s ss in 90 2 S-2'1 ^|2 2 < bc H 2Q ^ 03 p 2^2 E ^ 8 H i2 § Q c" 8 Q (M ^ >fO V- X ^03 X Jr.S a q) c^ U 52''co P u c y p a Sh . ax X ^ y y y O a;:n C0I3 - I E a y HJ ^ 'j 3-0. .E ^ y H. >:S E o 2-p 3 X p y s £ 8 |< 8 H ^'S d re Q ^2 ^ ^ CO ^ap X ^p ^ X y X (M u a y w c2 a^ re ^ ►?33 [ T« ] fras, Tilia, Vitis, etc. emulsifiable concentrate to trate; or 1 qt. 25% DDT 20 gal. emulsifiable concentrate plus 1 pt. Aramite 25% emulsifiable concentrate 03 0 ir5 *50 — Q il-l I ^ CM y H ^ § Q cr u i Q O (U'w ^oB CM a cu c •:: 03 ^ re LO h ^ c cu ^ £ o re u <1 4J re 1— I ’So crt 3 ^ £ a 03 ^ o 03 X i-j CQ ^ o S> rc H Q Q Si 11 CM a 03 CM IS qi: re 3 *J' S ^ 03 CX H ^ Q ^ Q re ^ c LO 03 CM U . 03 S re" 'x; 3 o 3 re c n. 03 w x" ^ ' = u £ 03 5 03" i 3 £ I W ’53 £ C 0) 3 y W c/5 LC < H I be o $11 a re c/3 3 ^ Q 03 -Q S CSI 03 u ^ 0 i ll w "re £ £ ^ 03 CC3 £-§ 0 c re u a 03 ^'O y be c re 'O X (D U 03 .£* S *£ 3 03 nC/5 ^ a 0” I [77] PESTS FREQUENTLY DESTRUCTIVE IN THE ARNOLD ARBORETUM Pest Antliraciiose Asli and Lilac Borer Bacterial Blijrlit Beech Bark Louse Birch Leaf Miner Black Vine Weevil Boxwood Leaf Miner Cankerworin Cedar-apple Rust FJm Bark Beetle FJm Leaf Beetle Elm Leaf Miner Euonymus Scale European Pine Shoot Moth Flat-headed Apple tree Borer Golden Oak Scale Hawthorn Leaf Miner Holly Leaf Miner Japanese Beetle Host Platanus, (^uercus Fraxinus, Syringa Syrinjra Fajjus Betula 'I'axus Spray Date May 1-10; May 15-^2 .5 M ay 1-10; M ay 1 j-25 May 1-10; May l.5-^J.5 Mar. 1-Apr. "20 May 15-25; July 10-15 June 1 5-25 Buxus, esp. B. micro- May 15-25 phylla, B. sempervirens Acer, Carya, Catalpa, May 15-25 h'raxinus, Juglans, Prunus, Quercus, Syringa, Tilia, Ulmus Malus, esp. M. soulardi, Mar. 1-Apr. 20 Crataegus, Juniperus Ulmus Ulmus Ulmus Celastrus, Dirca, Euonymus Pachistima and Pachysandra Pinus, esp. P. mugo, P. nigra, P. resinosa, P. sylvestris Rosa, Sorbus, esp. R. rugosa, Malus, etc. Quercus Crataegus Ilex, esp. 1. opaca Apr. 15-80; June 25-July 5 May 15-25 May 15-25 Mar. 1-Apr. 20 ; May 25-June 5 June 25-July 5 ; Aug. 15-25. May 25-June 5 ; June 25-July 5 ; Aug. 15-25 June 25-Julv 5 June 1-10; June 25-July 5 Mar. 1-Apr. 20 May 15-25 May 15-25; June 1-10 Aesculus, Ampelopsis, July 10-15; July 20-25 Hyd rangea. Metasequoia, Rosa, Sassafras, 'filia, \Jtis [ 78 ] Pest Juniper Scale Kalmia Leaf Spot - Lacebugs Larch Case Bearer Locust Borer Mottled Willow Borer Oyster Shell Scale Peach Tree Borer Pine Bark Aphid San Jose Scale 3 uJ I Scurfy Scale Spruce Gall Aphid Tent Caterpillar White Pine Weevil Willow Leaf Beetle Host Juniperus Kalmia Amelanchier, Azalea, Crataegus, Cotoneaster, Kalmia, Pieris, Rhodo- dendron, Sorbus Larix Robinia Salix, esp. shrub types Celastrus, Fraxinus, Populus, Syringa, etc. Prunus persica Pinus, esp. P. strobus Chaenomeles, Malus, Prunus, Pyrus, etc. Chaenomeles, Malus Picea, esp. P. abies, P. pungens vars. Malus, Prunus, etc. Pinus strobus Salix Spray Date Sept. lo-Oct. 30 May 15-25 May 15-25; June 1-10; June 25-July 5 Mar. 1-Apr. 20 May 1-10 Sept. 25 Mar. 1-Apr. 20 July 10-15; July 20-25 May 15-25 Mar. 1-Apr. 20 Mar. 1-Apr. 20 Mar. 1-Apr. 20 May 1-10 May 1-10; May 15-25 May 15-25 GENERA FREQUENTLY PLAGUED WITH PESTS IN THE ARNOLD ARBORETUM Genus Acer A esc 111 us Anielancliier Ampelopsis Azaleas Betula l^uxus Carya Catalpa Celastrus ( 6 Chaenomeles Cotoneaster Crataegus ( ( 4 4 Dirca Kuonymus Fagus Fraxinus ( 4 4 4 Hydrangea Ilex Juglans Pest Cankerworm Jajianese Beetle Lace bug Japanese Beetle Lace bug Birch Leaf Miner Boxwood Leaf Miner Cankerworm Cankerworm kmonymus Scale Oyster Shell Scale Scurfy and Jan Jose Scale Lacebug Cedar-apple Rust H awthorn Leaf Miner Lacebug Euonymus Scale Euonymus Scale Beech Bark Louse Oyster Shell Scale Ash and Lilac Borer Cankerworm Japanese Beetle Holly Leaf Miner Cankerworm [ 80 ] Spray Date May July 10-13; July ^20-^25 May 13-^3; June 1-10; June 3- July 3 J uly 10-13; July 20-t^3 May 13-23; June 1-10; June 23-July 3 May 13-23; July 10-13 May 13-23 May 13-23 May 13-23 May 23-June 3 ; June 23-July 3; Aug. 13-23 Mar. 1-Apr. 20 Mar. 1-Apr. 20 June 23-July 3 Mar. 1-Apr. 20 May 13-23 June 1-10; June 23-July 3 Mar. 1-Apr. 20 ; May 23-June3 June 23-July 3; Aug. 13-23 Mar. 1-Apr. 20 ; May 23“June3 June 23-July 3 ; Aug. 13-23 Mar. 1-Apr. 20 Mar. 1-Apr. 20 May 1-10; May 13-23 May 13-23 July 10-13; July 20-23 May 13-23; June 1-10 May 13-23 Genus Pest Spray Date Juniperus Cedar-apple Rust Mar. 1 -April 20 ‘ ‘ Juniper Scale Sept. 15-Oct. so Kalmia Kalmia Leaf Spot and Lacebug May 15-25 ‘ ‘ Lacebug June 1-10; June 25-July 5 Larix Larch Case Bearer Mar. 1-Apr. 20 Malus San Jose and Scurfy Scale, Cedar apple Rust Mar. 1-Apr. 20 i 6 Tent Caterpillar May 1-10 i i Flat-headed Apple tree Borer June 1-10; June 25-July 5 Metasequoia Japanese Beetle Juh’ 10-15; July 20-25 Pachistima Euonymus Scale May 25-June 5; June 25-July 5; Aug. 15-25 Pachysandra Euonj’mus Scale May 25-June 5; June 25-July 5; Aug. 15-25 Picea, esp. P. abies and P. pungens Spruce Gall Aphid Mar. 1-Apr. 20 Pieris Lacebug May 15—25; June 1-10; June 25-July 5 Pinus strobus White Pine Weevil May 1-10 Pinus, esp. P. strobus White Pine Weevil, Pine Bark Aphid May 15-25 Pinus, esp. P. mugo, European Pine Shoot June 25-July 5 P. nigra, P. resinosa, P. sylvestris Moth Platanus Anthracnose May 1-10; May 15-25 Populus Oyster Shell Scale Mar. 1-Apr. 20 Prunus San Jose Scale Mar. 1-Apr. 20 ( 6 Tent Caterpillar May 1-10 4 4 Cankerworm May 15-25 Prunus persica Peach tree Borer July 10-15; July 20-25 Pyrus San Jose Scale Mar. 1-Apr. 20 [81] Genus (^uercus Rhoclodeiidron Robinia Rosa, esp. R. rufjosa 4 ( 4 4 Salix Salix, esp. shrub tj’pes Sassafras Sorbus S.vringa 4 4 4 4 Tax us Tilia 4 4 Ulmus < ( Vdtis Pest (jolden Oak Scale Antliracnose Canker worm Lacebui^ I^ocust Borer Flat-lieaded Apple tree Borer Japanese Beetle Willow Leaf Beetle Mottled Willow Borer Japanese Beetle Flat-headed Apple tree Borer and Lacebug Oyster Shell Scale Ash and Lilac Borer and Bacterial Blight Ash and Lilac Borer, Bacterial Blight and Cankerworm Black Vine Weevil Cankerworm Japanese Beetle Elm Bark Beetle Cankerworm, Elm Leaf Beetle and PJm Leaf Miner Elm Bark Beetle Japanese Beetle Spray Date Mar. 1-Apr. ^20 May I- 10; May 15-2.) May 15-25 May 15-25; June 1-10; .June 25 -.July 5 May 1-10 .June 1-10; June 25-July 5 July 10-15; July 20-25 May 15—25 Sept. 25 July 10-15; July 20-25 June 1-10; June 25-July 5 Mar. 1-Apr. 20 May 1-10; May 15-25 May 15—25 June 15-25 May 15-25 July 10-15; July 20-25 Apr. 15-30 May 15-25 June 25-July 5 July 10-15; July 20-25 [8-2] A FEW DEFINITIONS Aramite: 25% emulsifiable concentrate — a miticide containing 25% aramite in a form which will mix with water. Used to control red spider or mites on ornamental plants. Blood Albumen: An emulsifier used especially with dormant oil to make it mix more easily with water. DDT: A chlorinated hydrocarbon (dichlorodiphenyl trichloroethane) It is both a stomach and a contact insecticide, helpful in con- trolling many chewing insects including elm bark beetles, cankerworms, gypsy moth and Japanese beetles. As it kills many predators, a build-up of mite population and to some extent aphids and some scale insect populations may follow its use. 25% DDT Concentrate: A liquid, containing one fourth of its weight as DDT, form- ulated so it will form an emulsion in water. 50% DDT Wettable Powder: A dry powder, containing one half its weight as DDT, form- ulated so it will make a suspension in water. Dieldrin: A chlorinated hydrocarbon insecticide. Useful for control of wireworms, other soil insects and some ants. As a foliage spray it will kill young miners in their mines. DN or Dinitro: Compounds are derivatives of phenol and cresol. As a dor- mant spray it will kill aphid eggs, some scales such as euony- mus, scurfy and oyster shell. Also it will kill some overwin- tering fungi at dormant spray strength. DN— Slurry: A watery mixture of the above dinitro compounds principally : Elgetol (l9% sodium dinitro ortho-cresolate) ; and Krenite (l9% sodium dinitro-ortho-cresol). Will discolor painted surfaces or stone. Fungicide: A material which will kill a fungus, especially when it can contact the fungus outside the plant tissues. Lead Arsenate: The chemical compound containing the two stomach poisons or lead and arsenic. A poison for chewing insects such as bag- Arsenate of Lead: worms, cankervvorms, and many beetles. It has been to a great extent superseded by the newer insecticides, especially DDT. [88] Lime Sulfur: A combination of lime and sulfur used as a contact insecticide and fungicide, available as a licjuid or in a dry (powdered) form. As a dormant spray it will control San Jose, pine needle and other scales as well as many aphids. Will discolor painted surfaces. Lindane: A purified form containing at least 90% of the gamma isomer of benzene hexachloride (BHC). Lseful to control some aphids, leaf miners, lacebugs and some soil insects. Miticide: A compound especially adapted to the control of mites and red spiders. Three of these newer compounds are “Aramite,*’ “ Di-mite” and “Ovotran.” Parathion: An organic phosphate insecticide, very toxic to insects but also very toxic to humans unless used with proper precautions. Carefully used, it will control aphids, mites, mealy bugs, some scale, nematodes, and some chewing insects. Puratized Apple Spray: A mercuric fungicide used to control, and often help eradicate, fungi. For anthracnose of sycamore and oak. Puratized Agri- cultural Spray is quite similar but is used at about twice the amount as the Apple Spray. Sulfur, Dusting: A very finely ground form of this elemental chemical used primarily as a fungicide to control powdery mildews, rusts, and leaf spots. It will also help keep down mite populations. Do not apply in very hot weather as it may injure any plant under these conditions. Sticker: A material added to the spray to make it adhere to the leaf surfaces. Calcium caseinate, wheat flour or powdered skim milk are examples. Robert G. Williams Alfred J. Fordham 6ray Herbarium Harvard Universitv INDEX TO VOLUME XIII 8 1954 Illustrations are in bold face type Aegopodium podograria, 1 1 Akebia quinata, 7 Among the Best Common \ ines, 18 “ Ground Covers, 19 Ampelopsis brevipedunculata, 7 Aramite, 83 ! Arctostaphylos uva-ursi, 1 1 [ Arsenate of Lead, 83 | Automatic Mist Sprayer, bb j Azalea amoena, 32 “ Bloom, Two Months of, 29 , Order of Bloom, 29 I Blood Albumen, 83 Campsis tagliabuana Madame Galen,*' 7 Carbon bisulfide gas, 50 Case Estates of Arnold Arboretum, 19 Cleaning Seeds, 47 j Clematis montana rubens, 8 j Clematis montana rubens, I’late 1,3 | texensis, 8 “ vitalba, 8 Collecting Seeds of Woody Plants, 41 Cytisus purpureus, 1 1 DDT, 52 “ Concentrate, 83 Wettable Powder, 83 Dieldrin, 83 Diervilla lonicera, 1 1 DN or Dinitro, 83 DN-Slurry, 83 Doorenbos, Mr. S. G. A., 2b Dormancy, 42 Estimated Blooming Dates of Major Displays in Arnold Arboretum, 40 Euonymus fortune! colorata, 8 hLuonymus fortune! kewensis, 12 minima, 12 FLvergreen Ground Covers, 7 Exhibit of Pruning at 1953 Boston Spring Flower Show, 21 PLxperiments in Dormancy, 55 Fermate, bb Forsythia ^\\rnold Dwarf,** 12 For the Record, 37 Fruits of ornamental woody plant genera, seeds of which should be cleaned before shipping, Plate IX, 43 Fruits of ornamental woody plant genera, seeds of which should not be allowed to dry out prior to sow- ing, Plate X, 49 Fruits of ornamental woody plant genera requiring no cleaning be- fore shipping, Plate XI, 53 Fungicide, Girdling Root, 23 Ground Cover Demonstration Plots, Plate IV, 13 Ground Cover for Different Purposes, 5 Ground Cover for Dry Soil, 5 “ “ “ Shade, 5 “ less than b inches high, 5 Ground Covers, Twenty -three of the Best for Massachusetts Gardens, 2 Ground Covers which increase rapid- ly, 5 Hedera helix baltica, 10 Flybrid Azaleas, 29 Ilydranjjea petiolaris, 10 Hydranjjea petiolaris, I’late II, 6 1 1 ypericuni buckleyi, Iberis sempervirens (iem,” \-2 Iiiditjofera incarnata alba, 1*2 “ kirilowi, 1 i Juniperus cliinensis sarf^eriti, 1 1 horizontalis, 1 1- “ plumosa, 11- Latex emulsion, 07 Layering Plants in Holland, ‘25 Lead Arsenate, 83 Leiopliyllum buxifolium, 14- Leucothoe catesbaei, 14- Lime sulfur, 84 Lindane, 84 Lonfjevity of Ornamental Woody Plant Seeds, do Longevity of Seed in Storage, o6 Lonicera henry i, 10 Low temperatures, 38 L.vsimachia nummularia, 16 Mild Winter Temperatures, 37 Miticide, 84 New Propagating Unit, 6t2 New Spray Materials, 69 Order of Bloom of Azaleas, 29 Pachistima canbyi, 16 Pachistima canbyi, Plate V, 15 Pachysandra terminalis, 16 Packing Materials Prohibited, 52 Parathion, 84 Permit for Plant Introduction, 52 Pests Frequently Destructive in the Arnold Arboretum, Plant Propagation, New Methods, 61 Quarantine Laws, 51 Plants Damaged by Snow or Low I'emperature, 39 Plants Frequently Plagued with Pests in the Arnold Arboretum, 80 Plastic Propagating Units, 6() Polyethylene Film, Another Method of Using in Propagation of Cut- tings, 66 Polyethylene Film in Air Layering, 67 Polyethylene film in plant propaga- tion, Plate XIII, 65 Polyethylene film, three uses in plant propagation, Plate XII, (53 Polyethylene Plastic Film, 62 Polygonum auberti, 10 Polygonum auberti, Plate III, 9 Polythene Bags, 51 Potassium Permangenate, 51 Procedure in Shipping Seeds, 52 Pruning, Exhibit of, at 1953 Boston Spring Flower Show, 21 Pruning Ornamental Shrubs and Trees, 21 Pruning, What to Prune, 21 “ When to Prune, 21 Puratized Apple Spray, 84 Rainfall, 37 Rhododendron albrechti, 30 arborescens, 35 Rhododendron arborescens, Plate VII, 35 Rhododendron atlanticum, 34 calendulaceum, 35 canadense, 32 gandavense, 34 japonicum, 35 kosterianum, 35 mucronatum, 30 mucronulatum, 30 nudiflorum, 35 “ obtusum, 32 “ “ amoenum, 32 “ “ arnoldianum 32 4 i (4 H inode- 3^ 31- kaempf’eri, 32 roseum, S5 schlippenbachi, 32 vaseyi, 34 viscosum, 3o yedoense poukhanense Rhododendron yedoense the “Yodo- gawa” Azalea, Plate \ III, 33 Rhodora canadensis, 32 Rhus aromatica, 16 R-osa wichuraiana, 16 Rotenone Dust, 50 Saran Cloth, 67 Seed Collection Dates — Chronologi- cally, 42 Seeds that can be stored dry and sown within the year, 54 Seeds that can be sown or stratified as soon as ripe, 54 Seeds that should not be allowed to dry out in shipping, 54 Seeds of Woody Plants, 41 Shipping seeds, 50, 51 Shrub Rejuvenation, 23 Shrubs withstanding snow and ice for 24 hours, 39 Snow, 38 Some of the Best Vines and Ground Covers for Massachusetts Gardens, 1 Sources for Vines and Ground Covers, 2 I Spray Schedule of Arnold Arboretum, I • 73-77 I Stratifying Seeds in Plastic, 67 Sticker, 84 I Styrofoam, 62-66 j Sulfur Dusting, 84 Synthetic Hormones, 61 Teucrium chamaedrys, 18 The Arnold Arboretum Spray Sched- ule, 73-77 I Vines Climbing by means of Tendrils or Twining Leaflets, 4 Vines, Clinging, 4 Vines for Colorful Fruits, 4 j “ “ Different Purposes, 4 “ “ Flowers, 4 “ “ Ground Covers, 5 Vines, Hardiness Note, 7 Some of the Best and Ground Covers for Massachusetts Gardens, 1 Vines, Twining, 4 Vines Withstanding Dry Soil Condi- tions, 4 Vines Withstanding Shade, 4 Waring Blender, 48 Weevils, 50 Wisteria floribunda macrobotrys, 10 rosea, 11 Woody Plant Seed Manual, 41 1 Xanthorhiza simplicissima, 18 Xanthorhiza simplicissima, Plate VI, 17 [87] ' ■' V. ^'..v