Firethorn (Pyracantha) in Northeast Illinois; A Second Look

Transcription

1 Firethorn (Pyracantha) in Northeast Illinois; A Second Look By Albert S. Roufja The neighbors on the south side of my home are fortunate each year in being treated to a colorful sight in our yard--one which we are unable to see except by walking around the house. It starts in late summer when the three large bushes planted next to our south-facing foundation begin to show their heavy clusters of bright orange berries. Their uninhibited display does not unfold all at once, but over a period of about two months. The bush near the southeast corner is well over seven feet high, and only by constant and liberal trimming am I able to keep it from luxuriantly obscuring the window. This shrub never fails to fruit, beginning about the last two weeks of August. The other two bushes, kept somewhat smaller by heavy pruning in recent years, begin to show their fruits in the late days of September, and then the colorful show is complete. Firethom is the common name for these thorny shrubs, and, indeed, the vivid orange fruits do offer a fiery display! The common name is a direct translation of the generic name Pyracantha, which is formed by the Greek pyr ("fire" ) and acanthos ("thorn"). On some early fall days we become aware of migrating robins (I like to consider them as Wisconsinites) which strip the bushes near our house of their plump orange fruits and fly away southward with full bellies and never a second thought. We may be fortunate, nevertheless, and have some fruit left on the shrubs until Christmas, or occasionally later, before prolonged winter temperatures dull their glow and snow covers them temporarily from view. In autumn, the small lustrous leaves, dark green above and lighter below, remain on the twigs and provide a natural foil for the clusters of fruits that brighten the shortening autumn days. By winter's end in March or April, most of the exposed foliage has turned a rich brown, but sheltered twigs (or, in mild winters, the whole bush) still bear some green leaves until late in the spring when the new growth begins, testifying to the fact that pyracanthas are considered evergreen in climates gentler than ours. Periodically I am reminded that these beautiful berried bushes are not commonly thought to be hardy here-yet these specimens and others growing in the Chicago area are exuberant contradictions to this notion. For readers who are not familiar with firethorns, a brief description may be helpful. There are several species of Pyracantha in the world, but the hardiest horticultural varieties are descended from P. coccinea, the wild species native to southeastern Europe and parts of Asia. Plants of this species grown from seed collected in the wild show great variation, differing in growth characteristics, including form, abundance of flowers, abundance and color of fruit, and in many other respects. Such variation is typical of most wild plant populations and must have characterized the firethorns of this species when they were brought into European cultivation in the late sixteenth or early seventeenth century. The general habit of seed-grown plants probably ranges from true dwarfs to low-spreading or large and sprawling shrubs. Most of the latter, however, if left to themselves, tend to grow into dense bushes that may reach ten or more feet in height. Because of this Dr. Rouf]a is Professor of Biology at the University of Illinois, Chicago Circle Campus. 17

2 prodigal growth, pyracanthas traditionally have been sheared as hedging or pruned as espaliers- usually in late summer, early fall, or in the early spring-to grow flat against walls or trellises. Firethorns, as their name implies, are usually quite thorny, although there are thorn-free varieties. In some respects the twigs resemble those of the flowering quince, a relative of Asiatic origin. The leaves, glossy when mature and rather small with shallow teeth along their margins, are borne on the twigs in alternate arrangement. The twigs and leaves are usually silky with hair when young, but the leaves may lose much of this hair and become smooth and shiny when mature. There are also non-hairy varieties. The berry-like fruits, so much like miniature clusters of mountain ash fruits, may ripen to be orange, yellow, or reddish-orange in different varieties. The fruit is of a special kind called a pome, typical of many representatives of that large and economically important Rose Family to which Pyracantha belongs. The white flower sprays of pyracanthas are small and not overly showy. They resemble, superficially, sprays of spiraea or chokeberry, also members of the Rose Family. The main reason for growing firethoms is the attractiveness of their berries. They are, however, of borderline hardiness in this area and if we are to enjoy these plants here, they must not only be planted in a proper location, but be capable of flowering and bearing fruit each year. FIELD TRIALS IN THE CHICAGO REGION About ten years ago, I realized that it might be well to take a second look at Pyracantha, along with some of the other woody ornamental plants of borderline hardiness in the Chicago area. Pyracanthas had not been tested locally on a systematic basis, and I arranged for a field trial on the University of Illinois Experiment Station grounds adjacent to the Morton Arboretum. It was hoped that breeding stock for hardy fruiting plants could be obtained if the trials were successful. The field trials were not of long duration, data being taken only for a three-year period; nevertheless, some useful observations were made. Five kinds of pyracantha which showed reasonable promise of being hardy and of being able to flower and fruit successfully were chosen for the trial. The site was an open field with a gentle slope, facing southwest. In April of the first year, one hundred plants were set out in freshly plowed sod which had consisted primarily of quackgrass. As one can easily imagine, weeding was difficult in newly turned sod and was not done with any regularity throughout the summer. After an initial watering, no irrigation was available. Despite these cultural drawbacks, sixty percent of the plants had survived by the fall of the first year. During the first winter, marsh hay was used to protect the plants, and no subsequent winter protection was given. At the end of the third year, fifty percent of the original plants had survived, in one condition or another. For the field trial, the firethorns chosen and obtained from nurseries were: P. coccinea 'Lalandei,' P. coccinea 'Kazan,' P. coccinea 'Pauciflora,' P. angustifolia, and a firethorn called 'Runyan Red,' apparently a coccinea type. The latter three proved to be unsuitable for one reason or another. The plants reputed to be P. angustifolia did not fit the taxonomic description for this species but instead appeared to be typical coccinea. The 'Pauciflora' lived up to their name (which means "few flowers") and produced virtually no flowers or fruit, nor did they commend themselves much in any other way. 'Runyan Red' showed poor performance in surviving and produced no flowers or fruit, seeming to support the dogma that red-fruited species and varieties are less hardy in our area. Specimens of 'Runyan' at the Arboretum have been similarly unsatisfactory. The two varieties of which some but not all specimens proved to be best both in survival and in fruiting were 'Lalandei' and 'Kazan,' both coccinea types. Two of three firethorns planted beside my house are 18 Opposite: A well-fruited branch of P. coccinea 'Lalandei' (Burwell).

3 a legacy of this field trial, one plant of each of these cultivars having been randomly selected from the original lots which showed high performance. I say only some of 'Lalandei' and 'Kazan' performed well because, as the field trial progressed, the performance of these two varieties showed a behavior pattern which seemed to correlate consistently with their source. Specimens of each of these two cultivars had been obtained from three different nurseries. One nursery provided three-year-old container-grown plants of 'Lalandei,' and the rest were supplied as younger plants in bands or small pots. In the field trial each nursery source was represented by a number of specimens which were located at random in the plot. Yet the plants from each nursery performed differently from those with the same cultivar name obtained from the other nurseries. For example, in terms of some of the most important characteristics-precocious flowering, fruiting, and winter hardiness--only the 'Lalandei' from the Burwell nursery of Columbus, Ohio, and the 'Kazan' from the Siebenthaler Company of Dayton, Ohio, performed well. The question then arose as to why the plants from each of the several nurseries performed differently. There was a rational possibility that differences in cultural practices at the nurseries might have accounted for this, but it seemed much more likely that there were inherited differences that predisposed the plants to behave as they did. If this were so, it was probable that both 'Lalandei' and 'Kazan' had been propagated from seeds at some time in their history rather than from cuttings.

4 ORIGINS AND CHARACTERISTICS OF 'LALANDE!' AND 'KAZAN' It was not until I had looked more carefully into the rather scanty literature on the origins of P. coccinea and of its cultivars 'Lalandei' and 'Kazan' that the results of our field trial began to make sense. We are especially indebted to B. K. Boom, of the Institute for Horticultural Plant Breeding at Wageningen, Netherlands, for his publication in 1959 of botanical and horticultural information concerning the original Pyracantha species and especially for his discussions of 'Lalandei' and 'Kazan.' In this publication he :tlso referred to an informative article by Gerd Kriissman, Director of the Botanical Garden at Dortmund, West Germany, published earlier in that same year, which provides us with a documented record of the origin of 'Kazan.' After reading Boom's descriptions and Kriissman's account of his search for the obscure origins of 'Kazan,' the pieces virtually fit together like a jigsaw puzzle. 'Lalandei' was named for M. Lalande, a French nurseryman of Nantes, who in 1874 selected a plant from a group of P. coccinea seedlings that showed certain characteristics he deemed worthwhile. When mature, the plant's form was rather broad and flat, lending itself to training against a wall; its orange fruits were produced abundantly and precociously, and the leaf margins were more finely toothed than on the wild form. This selection, later called 'Lalandei' in the nursery trade, was propagated both from seed and by cuttings. The seedlings, first from natural sowings around the original plant and subsequently from plants of the progeny of later years, often looked like the original selection described by Lalande. Consequently, according to Boom, "What is currently supplied [as 'Lalandei'] is not homogeneous... "This can be explained by the biological fact that seed production is a sexual process involving recombinations in the heredity of the offspring. Therefore one rarely finds or expects uniformity in a seedling population. Rooted cuttings, on the other hand, can be expected to be genetically identical (i.e., a clone) to the plant from which they were taken. It is reasonable to assume that even if a modem nursery has faithfully 20 Ripe fruits of P. coccinea cultivars 'Kazan' (left) and 'Lalandei' (right). Note the larger size of the 'Kazan.'

5 propagated its stock of 'Lalandei' strictly by cuttings, the plants may not be genetically identical to those of another nursery if the two nurseries obtained their original plants from different sources. Kriissman had long been interested in the cultivar 'Kazan' for reasons which will be covered later. According to his account, his search for the origin of 'Kazan' began by first looking at the plant files of the Spath nursery in Berlin to determine the source of their original plants of 'Kazan.' He found that these had come from the Bohlje nursery, the proprietors of which in tum informed him that they had obtained the variety around the year 1928 from a hedge growing in the garden of a Professor Wiepking in Berlin. A letter from the aged professor to Kriissman finally supplied the desired information. Wiepking, according to his own account, had been commissioned in 1922 to remodel or enlarge a park in Trieste, Italy, for a Baron Economo. "Quite by accident," wrote Wiepking, "during a visit in Trieste I found several Pyracantha of a type heretofore unknown to me. The Baron's Austrian gardener, Muller, told me that he had brought these plants back from the local botanical garden in Kazan, Russia. I took along cuttings [when I went] back to Berlin... " Wiepking then arranged to have the cuttings rooted at a friend's nursery, and in 1926 the young plants were set out in his own garden. Later these plants, by then grown into "heavy and healthy bushes," caught the attention of several other nurserymen, the first of which was J. Timm & Company of Elmshom in Holstein, Germany. According to Wiepking, this pyracantha was distributed by the Timm nursery under the designation 'Kasan.' (The German spelling when transliterated from the Russian cyrillic alphabet is 'Kasan'; phonetically the name is pronounced as spelled in English: 'Kazan.') The story seems to leave some gaps, but as Kriissman intimated, we are fortunate that Wiepking was alive and still remembered the salient details after thirty-five years. There is yet some question in my mind as to whether Wiepking brought cuttings from only one or from several of the plants he found in Trieste. His statement indicates that the Baron's gardener brought back plants from the botanical garden in Kazan, Russia (a city located between Moscow and the Ural Mountains). We may therefore surmise that these might well have been a group of seedling plants, much alike in appearance but different genetically. There is, then, the faint suspicion that the plants in Wiepking's garden in Berlin also may not have been genetically homogeneous. We have no way of knowing whether the several nurseries, including the original distributor, Timm & Company, took cuttings from one or several bushes in the professor's hedge. And, as with 'Lalandei,' we cannot know without a tedious search exactly how 'Kazan' has been propagated since then. According to Boom, "The descriptions [of 'Kazan'] which are to be found in catalogs, alas, are very short, and because of their incompleteness, the plants cannot be recognized." He decided to remedy this problem by tracing back the propagative line of the plants he purchased to those bushes in Wiepking's garden, a method useful for his purpose but a rather impractical method of identification for the average gardener or plantsman. By this method, however, he was able to formulate a description of a type specimen of 'Kazan' obtained from the Timm nursery which may be useful for posterity. According to published descriptions and my own observations, the growth habit of 'Kazan' differs qualitatively from that of 'Lalandei.' While the shoots of 'Lalandei' tend to grow irregularly and produce a sprawling bush suitable for training along a wall, those of 'Kazan' are more regular, resulting in a large yet more compact and symmetrical bush. For this reason, although 'Kazan' is not as suitable for training along a wall, it can stand on its own merits as a freely-growing bush that needs little specialized pruning or training. I have noted other comparisons between the specimens in my own yard of the 'Lalandei' originally obtained from the Burwell nursery and the 'Kazan' 21

6 from the Siebenthaler nursery. Of these two, I have observed that the fruits of the 'Kazan' ripen earlier in our climate, showing orange color about August 15. The 'Lalandei' fruits ripen about a month later. The fruits of 'Kazan' are also slightly larger than those of 'Lalandei.' I also noted that 'Lalandei' seemed to flower sooner as a younger plant than did 'Kazan,' but the latter caught up quite soon. There have been various claims of greater winter-hardiness in 'Kazan,' first noted by the German nurserymen who originally propagated the plants from Wiepking's hedge. Kriissman himself was impressed by the fact that during the "polar winters" of and in Berlin, no injury of any sort was observed. Among other advantages over 'Lalandei,' Kriissman observed that 'Kazan' tended to remain more evergreen even when exposed to winter sun. My experience has shown that 'Lalandei' (Burwell) and 'Kazan' (Siebenthaler) are of about equal hardiness as far as twig damage is concerned, but there is a somewhat greater tendency for 'Kazan' to retain green leaves throughout the winter, corroborating Kriissman's observations in Germany. My correspondence with G. W. Burwell indicates that their strain of 'Lalandei,' is considered by Dr. L. C. Chadwick of the Ohio State University to be a true 'Lalandei,' and that the horticulture department there has found it to be immune to fireblight disease, a serious problem encountered with certain plants in the Rose Family. FACTORS AFFECTING HARDINESS AND FRUITING IN NORTHEAST ILLINOIS Firethoms are well adapted to the hot, dry summers so common in northeast Illinois; indeed, they thrive and produce much of their growth in warm weather. A number of varieties, including some of P. coccinea, are popular in the hot, dry areas of the southwestern states where they are often espaliered against walls. One reason they can withstand hot, dry weather appears to be their habit of producing far-ranging root systems which enable them to exploit the soil moisture that sustains midsummer growth. This characteristic makes transplanting of old established plants virtually impossible. On the other hand, young container-grown or root-pruned field-grown plants dug with a generous ball of earth transplant easily, and are generally indifferent to the soil texture in which they are planted, growing well in heavy clay or in sandy soils. The problem of pyracantha hardiness in the Chicago area can be reduced to the factor of uncertain survival through extended periods of low winter temperatures. Our field trials ten years ago demonstrated quite conclusively that coccinea type firethoms growing in unprotected locations may winterkill down to the depth of the highest snow cover, but that they can still survive below this level. Immature twigs or portions of twigs generally do not come through the winter. Only those twigs that have been given the time to mature can survive if they are not exposed to prolonged periods of zero or subzero temperatures. Hence, after a cold winter one can observe that although some exposed twigs may have several inches of dead immature tips, the rest of the twig is actively growing new shoots and in many instances flowering abundantly. Obviously, both dead and living sections of the twig were exposed to the same winter weather; only maturity made the difference between life and death. To insure that exposure to prolonged cold is minimized, one should plant pyracantha in selected sites where the microclimate differs from the typical climate of our area. The most successful plantings from the point of view of consistent fiowering and fruiting are those made along the south side of a house or building or some other solid mass, where the warmth of exposure creates a localized environment that ameliorates our most bitter midwinter weather. The greater tendency toward browning of the leaves by the winter sun in this location does not appear to weaken the plants in any way. Indeed, the microclimate on the south side of a building, because of its posi- 22

7 tion facing the winter sun and the escape of heat from the building, can simulate the actual climate a hundred and fifty miles or more to the south of the site location. Also, as a shrub matures, it often creates or contributes to the improvement of its own microclimate. The increase in the mass of interlaced branches partly shades inner leaves, keeping more of them green throughout the winter than when the plant was smaller. Reduction in wind velocity and storage of heat in the woody mass of the shrub as it becomes larger may also play a part in better winter survival of pyracanthas. When south-facing sites are not possible, sites close to the east side of a building are second-best. As I stated previously, we should grow firethorns as ornamental plants because of the attractiveness of their berries. To be suitable for this area, plants must not only be able to survive the winters, but also be capable of flowering and bearing fruit each year. In my estimation, the explanation for the poor flowering and fruiting of pyracantha frequently reported in the Chicago area lies in insufficient attention to two factors: ( 1 ) the proper selection of plants which show a proven hereditary readiness-to-flower, beginning at an early age and continuing every year throughout the life of the plant; and (2) the proper selection of planting sites which offer microclimatic protection in winter. We have been inadvertently content to condemn merely second-rate material and ignore the best because we have not provided suitable conditions for growing them. One of the useful characteristics of certain pyracanthas (which also must have interested gardeners and nurserymen in the early years of their culture in Europe) lies in their ability to flower and fruit when very young. Generally, this habit of precocious flowering is associated with the ability to flower and fruit every year, although there is a tendency for pyracanthas, as in other fruit-bearing shrubs and trees, to bloom and fruit heavily and lightly on alternate years. The initiation of flower buds in pyracantha appears to require, first, an inherited flowering-factor which permits a response, and secondly, the proper environmental conditions to trigger that response. Just what the readiness-to-flower mechanism may be is presently unknown, but we do know that it is hereditary and that some plants have it in greater measure and at an earlier age than others. For example, 'Lalandei' (Burwell) seems to be slightly more precocious than 'Kazan' A twig of P. coccinea 'Kazan' growing on the south side of Hull House Dining Hall; photographed in May, The tip matured too late in the fall and was winterkilled. Note that the progressively older lateral buds on the living part of the twig below produced correspondingly larger numbers of flowers, fruits, and leaves. 23

8 ( Siebenthaler). Plants which show precocious, frequent, or abundant flowering are desirable, and they should be propagated vegetatively, in this case by cuttings, to perpetuate these characteristics. Environmental or climatic factors affecting flower bud initiation are also important. Just how important was illustrated in a study reported in 1961 by Reisch, Chadwick, and Hildreth of the Ohio State University, Columbus, Ohio. They found that flower buds on pyracantha were initiated in fall during shortening days and cooler temperatures. I have reason to question the direct influence of day-length on flower bud initiation, because plantings of 'Kazan' on the south side of the Hull House Dining Hall at the University of Illinois Chicago Circle Campus have flowered, even though they are illuminated all night year-round by a high intensity floodlight. In one instance the light is located only thirty feet away, and, indeed, flowering appears more abundant on the side of the bush nearest the floodlight. In the Ohio study, initiation began about October 24 in Columbus and in that milder climate continued to occur sporadically into March. At that latitude it was noted that flower initials formed in the fall continued some development during the winter (presumably when temperatures were above freezing) but that their greatest growth took place in April. Flowering buds usually occur in the leaf axils of well-hardened (i.e., well-matured) first-year shoots, but may occur in buds at tips of main shoots as well. In the Ohio study, there was evidence that initiation of flower buds began to occur specifically at about the same time that growth in length of stems ceased, or at the time when stem hardening (maturing) was taking place or had been already completed. After initiation, these buds overwintered in a rudimentary condition. I have since corroborated the Ohio study by finding rudimentary flower initials from buds collected in midwinter in our area. It has also been increasingly obvious after ten years of observations that these flower initials are not necessarily more sensitive to cold than the rest of the shoot, as is the case in many other borderline ornamental shrubs. This is a very. important feature. Since only the more mature twigs or portions of the twigs seem to be capable of forming flower initials in their buds, and since maturity enhances the ability to survive winter cold, it is in fact those portions of the shoot that eventually bear flowers (or are potentially capable of bearing them) that actually survive if the conditions are favorable for survival. In short, a firethom which grows well vegetatively but which does not bear fruit does so, not because the flower buds have been winterkilled, but because flower buds were never initiated at the proper time at the end of the previous growing season. By late May or early June a firethom should have open clusters of small white flowers being actively pollinated by bees. If, however, old branches show only leafy growth, then it is obvious that no flowers were initiated the previous fall. There may be several different reasons why flowers are not initiated at that time. In more benign climates than our own, most varieties of firethom experience little difficulty in producing flowers and setting fruit on a yearly basis. This is not the case in the Chicago area. As mentioned previously, a sheltered site mimics a more southerly climate than our own. Most importantly, fall temperatures favorable for continued maturing of twigs and the eventual initiation of flower initials in the buds may be prolonged for many more weeks. Also, the duration of extremely low stem-killing temperatures in midwinter may be limited. In such a sheltered microclimate, the ground does not always freeze deeply and, as in more southerly climates, the spring warming process may be hastened. If fruiting is poor or erratic under protected conditions, then one can only assume that either a poor hereditary disposition to flower or certain other environmental difficulties may be the cause. For example, reasonably successful plantings of pyracanthas can be seen at the Arboretum, where 24

9 specimens of 'Lalandei' flank the south doorway to the Administration Building. They have been growing well and have fruited occasionally since However, these particular plants, growing in raised beds that are confined by thick walls, tend to be slow-growing. One possible explanation may come from the fact that because of their site, these specimens have a limited horizontal rootrun, contrary to the normal wide-ranging root system of pyracanthas. This would impose a limitation on the amount of water and nutrients available to sustain new vegetative growth each season and thereby limit the number of mature twigs available for flower bud production. Pyracanthas have also been growing at the Arboretum on the southwest-facing slope near the top of Frost Hill (east of the four pillars) where they are protected on the northeast by a grove of conifers. These plantings, started in 1958, have done quite well vegetatively, and the three 'Kazan' specimens have occasionally produced heavy crops of fruit. The limiting factor in fruiting of the Frost Hill plantings may be the diminished microclimatic protection afforded by the less solid mass of conifers. DISCOVERING AND PROPAGATING HARDY FRUITING STRAINS Admittedly, the landscaper or homeowner who wishes to give firethom a place in his artistic scheme may still have some difficulty obtaining plants which can be assured not only of reasonable hardiness but also of consistent flowering and fruiting. I would say (with some reservations) that if all material were propagated vegetatively, any plants labeled 'Lalandei' or 'Kazan' would probably be suitable, provided they were given a proper planting site. However, since plants marketed under these names may have been derived directly or indirectly from seedlings, there is a distinct possibility that within each cultivar there may be some variation in characteristics. There are probably a number of clones and, of course, any number of seedlings capable of flowering and fruiting in our area. These could be discovered with relative ease by proper testing and culling outof-doors in properly selected sites. This need not require prolonged periods of trial since desirable pyracanthas can be selected as soon as possible for precocious blooming; if they behave otherwise, they should be quickly eliminated. Once discovered, there need be no difficulty in vegetatively propagating these desirable forms of pyracantha. Cuttings are quite easy to root and may be taken at nearly any time of the year. Early fall or early spring cuttings may be preferable, because the semi-hardened or hardened shoots taken respectively at these times of year do not have the wilting problems encountered with soft, recently emerged shoots of late spring and summer. I have found that rooting takes place in a one-month period on cuttings taken in early fall, stuck in sand, protected with a polyethylene cover, and grown under fluorescent lights two or three feet above the polyethylene at temperatures of F. Although hormone treatment does not hasten rooting, it does enhance both the possibility of rooting and the number of roots formed. While the traditional length of cuttings is made at about six inches, a recent study by Tioga, McGuire, and Parvin of Virginia Polytechnic Institute demonstrated that rooting can take place just as successfully with cuttings up to eighteen inches long. This has the advantage of producing a saleable plant for nurserymen more quickly. The number of Pyracantha cultivars has increased astronomically in the last decade or more. If I were to project any future from my second look at these fine ornamental shrubs, I would hope that someone would eventually test, select, and propagate firethorns for the Chicago area and couple this effort with a continuing search for hardier and better fruiting forms more suited to this climate than those now recommended. Indeed, the considerable genetic potential displayed by the number of Pyracantha cultivars now in existence, plainly shows us that we may be quite successful if we make the effort. (References on page 32) 25

10 INSECT LABORATORY. A new field laboratory has been built at the Morton Arboretum for use by the Illinois Natural History Survey, and is under the direction of Dr. James E. Appleby, of Urbana. Located on the far west side of the grounds, the laboratory will be used for research on life histories of insects and mites that are injurious to ornamental trees and shrubs in Illinois. Studies of these insects will include observations of their length of life; the intervals and seasons when the adult insects emerge, the eggs are laid, and the eggs hatch; the length of time the larvae feed; the way in which the larvae injure the plants; and the various kinds of plants which are hosts for specific insects. The Arboretum provides an excellent location for the Natural History Survey's insect laboratory because of the large number of labelled ornamental trees and shrubs located in one area and the availability of plant experts with whom to confer. The Arboretum will also benefit substantially from the information obtained by this close cooperation between the two organizations. Arboretum News and Notes NAPHEX 70. Entries in the nature photography exhibition, sponsored annually by the Morton Arboretum and the Nature Study and Camera Oub, must be submitted by October 19. Entry blanks may be obtained from the Arboretum's Education Department. In both the individual slide division and the series division, qualifying entries must depict a botanical, zoological, or geological subject or scene photographed in its natural geographical and ecological setting. A unique feature of the contest is the requirement that slide-makers provide minimal information about their subject : what it is, where and when it was photographed. This is consistent with the Arboretum's goal of encouraging the study of nature through photography and not merely the photographic recording of nature subjects. Naphex 70 is an International Salon, approved as a Restricted Exhibition by the Photographic Society of America. P.S.A. will award one medal to the individual slide judged best-in-show. The Morton Arboretum will present medals and cash awards in both divisions. : I Climatological Summary i ' Data February March April I : I 1 Average mean temperature! 25.2 F 34.l F! 50.1 F I I I I I Highest temperature i 5 1 F 57 F i 85 F Lowest temperature I' - 9 F 10 F!' 22 F Days maximum below 32 F Days minimum below 0 F l 3 0! 0 P rec1p1ta11on... I I 1 1 I 0.63" 2.10" l ', 5.22" ~ ~ ~ ~ ~ Pyracantha References: Boom, B. K Benaming, geschiedenis en kenmerken van een aantal houtachtige planten. N eder/andse Dendro/ogische Veremiging. Jaarboek 21: (Wageningen. Instituut voor de Verede/ing van Tuinbouwgewassen, Mededeling 157.) Krussman, G Zur Geschichte der Pyracantha coccinea 'Kasan.' Deutsche Baumschule 11 : Reisch, K. W., Chadwick, L. C., and Hildreth, W. R Ontogeny of the inflorescence of Pyracantha coccinea 'La/andi.' (abstr.) Amer. Soc. Hort. Sci. 58th Ann. Meeting. 32