SALT TOLERANT PLANTS GROWN IN SOUTH AUSTRALIA

LOTHIAN: SALT TOLERANT PLANTS 293 SALT TOLERANT PLANTS GROWN IN SOUTH AUSTRALIA T. R. N. Lothian, Director Botanic Adelaide, Garden South Australia Of all the sites in which we try to grow plants I have always considered that those near and along the sea front are the most dif ficult. For several years I have been interested in this problem, therefore you may gauge my feelings of pleasure when my kind correspond ent, Mr. Menninger, forwarded to me a copy of your 1952 Proceedings which contains a most interesting article on "Salt Tolerant Plants" by Miss C. R. Ferguson. Because there were a number of shrubs which we grow here but had not been listed, your Vice Presi dent suggested that I should write and tell you about them. The details given by Miss Ferguson in de scribing the natural environment and factors affecting plant growth by the sea coast need not be added to nor elaborated upon. I would emphasize their importance and draw the attention of all who wish to establish a garden near the coast. These conditions are found throughout the world and South Aus tralia is no exception. But its coast line is sharply contrasted with two distinct shore lines. Long stretches of our coast have the typical sandy shore, leading up to sand dunes which rise in some instances to a height of 100 ft, and secondly, precipitous cliffs often up to 300 ft. in height and frequently of lime stone. Because the only differences in the situ ation are likely to be (a) soil, and (b) the force at which the wind sweeps salt spray across the vegetation, I propose to deal with these two distinct habitats together. My de scriptions and comments on plants will be based therefore on their ability to grow along the coast, that is the first and second lines of defense. South Australia's coastline stretches for a distance of about 1,200 miles, from between the borders of Western Australia in the west to Victoria in the south east. Generally it faces south except for the two eastern coastlines of the deeply penetrating St. Vincent and Spen cer Gulfs. Further, about 130 miles south west of Adelaide lies Kangaroo Island. This island, roughly narrow rectangular in shape, lies east and west, therefore its southern coasts are pounded while its northern coasts are some what sheltered. The picture therefore oi Coast al South Australia, is that generally our coasts are exposed to the strong southerlies and re ceive a beating just as your east coast does, while the exceptions given above represent your west coast. Climatically we are somewhat different from you. Commencing from the Far West and working eastward the rainfall in these coastal regions (and for much of the hinter land too) rarely exceeds 12" per annum until Yorke Peninsula is reached. Here rainfall rises to between 18" and 22" while at the head of Spencer Gulf, at Port Augusta, the continental rainfall of 8" per annum is again recorded. Adelaide has 21", and once past the lakes region and the Murray Mouth, some 50 miles south east of Adelaide, rainfall increases until in the south east regions it is over 30" per year. Its value (owing to frequent drizzle or mist) is not great to plants unless sharply ris ing ground lies directly behind the shore, then drizzle, because of cooling atmosphere, be comes rain. In such localities, especially if a promontory gives protection, forest is pro duced. Generally our winters (May to September) are wet; 12" to 14" of Adelaide's 21" fall in this period. The summers are dry and hot with humidities being constantly registered be tween 20% to 30% and frequently very much lower. Winter temperatures can be generally stated to vary from 35 to 60, while in sum mer the variation is greater, between 45 and 90, the higher temperatures being recorded in the western districts while the south east area is usually considerably cooler. Strong cold southerlies blow in the winter, with hot,

294 FLORIDA STATE HORTICULTURAL SOCIETY, 1954 sand-laden north westerlies occurring in the summer. These figures, of course, relate to the coastal regions only, say a belt 200 yards deep, for both maximum and minimum tem peratures in the inland areas greatly exceed those given for the coastal regions. It can be seen from the above that we have considerably less rain than you are ac customed to, that long periods with hot and dry conditions can be expected, while our winter temperatures are considerably less than yours. In spite of this we are able to grow a number of the tropical plants listed among those recommended by Miss Ferguson. There are others which she has listed but which we cannot grow, and these include Croton, Allamanda, Acalypha, Codiaeum, Pandanus and a great many of the tropical trees and palms listed. Let us then look at some of the plants which we in South Australia grow along our coastal regions (and have not been included in Miss Ferguson's list). All can be planted in her groupings one and two, and despite climatic differences I am certain that most of them would survive with you. Two grasses which thrive in coastal regions are Spinifex hirsutus and Distichlis spicata. The former is always on the seaward side of sand dunes while the latter prefers heavier soils which are found submerged by brackish water during the winter months. Spinifex is a robust trailer of open growth and a useful sand-binder but is in no way related to the so-called "Spinifex" of the Interior which is referrable to the genus Triodia. Distichlis is a low-growing plant 3" to 6" high with leaves arranged in a distichous manner. As the growths are vertical it has little use as a po tential lawn grass. A South African plant, Arctotis stoechadifolia, is most useful. It is a prostrate grey-leafed plant with most attract ive large buff-cream coloured flowers and forms wide carpets of dense growth. It with stands our severest storms. Coming to the next group, climbers or vines, it is of interest to note that Tecomaria capensis is listed by Miss Ferguson as needing com plete protection, whereas I know of a couple of hedges of this plant within 25 yards of the high tide mark. Perhaps the conditions it ex periences here are not as severe as yours, or it may be because of the sandy soil it grows in. A most valuable native species is Muehlenbeckia adpressa, a wiry creeper with heartshaped leaves 1" to 13&" in diameter. This will establish quickly and give protection to less hardy plants. A scandent shrub, Buddleia madagascariensis which forms large masses of grey growths and foliage has spikes of yellow flowers, is a most useful coastal plant. More frequently it is treated as a shrub but it can be readily trained along wires or fences to form an attractive thicket. As it is somewhat drought resistant it is also useful within the 15" rainfall belt. It is difficult to decide which of our native shrubs is the hardiest under these bleak coastal conditions. A charming plant is Correa alba with white star-shaped flowers contrast ing sharply with the normal fuchsia-like flow ers one expects in this genus. It is a tough and resistant species and although only grow ing 18" to 24" high will withstand the bleak est conditions. A very valuable and salt re sistant species is Melaleuca pubescens, fre quently called the "Black Tea Tree" or "Moonah." By our rating this is at least four times as hardy as either M. hypericifolia or M. nesophila which are listed in the article previously referred to. M. pubescens grows in to a tree, its height depending on its protec tion. Along coastal regions it will reach 6 to 8 ft., where protection is given it will grow from 15 to 20 ft. As it withstands cutting it can form an effective hedge. It has thin, narrow, deep green foliage and "bottle brushes" of white flowers. Another valuable shrub, in this instance pre ferring somewhat sandy soils, is the coastal Tea Tree, Leptospermum laevigatum. A most decorative shrub growing up to 10 ft. high the trunk is covered with a fibrous bark and the leaves are narrow-oval, small and glaucous. The flowers are white and produced in great profusion during the early spring to late spring months. Its hardiness against coastal condi tions is unquestioned and as it can be trained and trimmed into a hedge it is a most suitable species for planting in this region. Acacia sophorae is our Coastal Wattle and is the broadleafed form of the closely related A. longifolia. It is considerably hardier than this species and is a first-class coastal plant. It thrives in moving sand and plants which are known to be 6 to 8 ft. high have but only 2 or 3 ft. emerging from the top of the dune, yet they flower freely each year. The flowers are in finger-like spikes and a clear yellow in colour. On heavier soils it grows more slowly

LOTHIAN: SALT TOLERANT PLANTS 295 but will survive as a screen and give protec tion to less hardy subjects. Two species of our Salt Bush form very useful shelter for less hardy plants. The gen era Rhagodia and Atriplex are widespread in Australia and usually inhabit halophytic situa tions. A. cinerea is an extremely hardy plant frequently found just above the high tide mark, and as it possesses grey foliage forms quite an attractive garden feature. A Compo site, Calocephalus Brownii, forms cushions up to 18" high and 24" in diameter, has silvery foliage and globular heads of yellow flowers. The Nitre Bush, Nitraria Sohroberi, is a rambling twiggy plant forming mounds up to 6 or 8 ft. high. It withstands the worst condi tions and will grow in heavy soils. As it with stands cutting it can be used as a hedge. Growing in amongst Acacia Sophorae is one of our daisy bushes, Olearia axillaris. This forms bushes up to 3 ft. high and its silverygrey foliage makes an attractive feature in our sand dunes. Like A. Sophorae it grows better in sand than in other soils. A. cyclopis (a native of Western Australia and there called Coastal Wattle) is a very hardy species and one which can withstand similar conditions to A. Sophorae. It will eventually grow 8 to 10 ft. high. One plant which not only withstands coastal conditions but saline as well is Myoporum insulare Boobyalla. One of our poets in a bright mood left the following verse pinned to the church door of one of our small seaside towns where conditions, so far as plant life is concerned, are very severe. "If Cypress fail this House of God Through wind and rain and saltiness of sod It may be through the grace of Allah You'll perhaps succeed with Boobyalla!" This plant is related to the New Zealand M. laetum and forms attractive plants up to 8 ft. high. It has light green lanceolate leaves, and during the season produces numerous small pinkish-white and spotted star-shaped flowers. It thrives best in light or sandy soils and with another species, M. platycarpa, is a wonderful plant for our dry inland (6-10" rainfall). Pittospurum crassifolium, the New Zealand "Karo", grows exceedingly well on coastal stretches. Forming small shrubs up to 8 ft. high it has attractive deep green and greyish leaves while the flowers are dark maroon. I was surprised to see neither Chrysanthemum Coastal planting: of ARAUCARIA EXCELSA, Nor folk Island Pine. Rounded headed tree at right is FICUS MACROPHYLLA, Moreton Bay Fig. i? YSAand» banh covered by ARCTOTIS STOECHADI- FOLIA. Note the dense foliage thus giving protection to the soil. frutescens Marguerite nor Myrtus communis, English or common Myrtle, listed by Miss Ferguson. It may be because your region is too warm and wet for these plants but these two, especially the former, are most hardy and wind resistant in our coastal regions with in the 20" rainfall belt. The latter, of course, grows quite successfully into a small shrub 4 to 6 ft. high, and as it withstands clipping it forms a very useful hedge. Baccharis halimifolia of course is well known for its ability to thrive under these difficult conditions. Ar temisia Absinthum is another exotic which is used by our inland as well as coastal garden ers. It is an extremely hardy plant withstand ing the worst storms. The silvery foliage makes an attractive feature. As it will grow into a bushy and thick shrub 2 to 3 ft. high and makes useful hedges, it should not be overlooked. Because of the warm and moist conditions you enjoy you are able to grow many more

296 FLORIDA STATE HORTICULTURAL SOCIETY, 1954 Two creepers useful for seaside planting: MUEHLENBECKIA ADPRESSA (dark leaf); TETRACONA IM- PLEXICOMA a species closely related to New Zealand Spinach (T. implexa). tree species than we can in South Australia. Most trees which survive under our coastal conditions are temperate in origin and be cause this region naturally produces fewer trees than in wanner climes we must rely more on smaller growing plants. However, we are slowly trying species which hail from our east and sub-tropical coasts, and in time the selection available should be greater. Of the strictly tropical species Ficus macrophylla, "Moreton Bay Fig", is the only species of this genus which has so far proved hardy in our coastal regions. In more sheltered areas it grows into majestic trees and probably its hardiness arises from the tremendous reserves it possesses. Another species of Casuarina, C. glauca the Swamp Oak, will form very effective shel ter along coastal regions. It has the advantage not only of growing well in either sand or heavy soils, but it suckers and these form a thick wind break. It will eventually reach a height of 25 ft. The most successful Pine we grow along the coast is Finos halepensis, "Aleppo Pine." This species not only can withstand salt winds but it thrives in alkaline soils such as are frequently found along coast al regions. One of our native Conifers, Araucaria excelsa, commonly known as the Nor folk Island Pine, is probably the hardiest of all trees which we can plant along the coast. It is native to the small, wind and storm swept Norfolk Island which lies about 250 miles east of Sydney and has been successfully introduced throughout the sub-tropical and temperate parts of Australia for coastal plant ing. The regular whorled branches form an attractive feature and when the tree is of large size it makes an imposing sight. Another plant from the Norfolk Island which is extremely hardy is Lagunaria Patersonii, variously known as the "Norfolk Island Hibiscus", "Pyramid" or "Cow-itch Tree" (this last name because of the spicules found in the seed capsules). This evergreen tree grows to a height of 25 to 30 ft. even under the worst coastal conditions. A short distance inland trees over 60 ft. high are known. It has ovate lanceolate leaves and during the sum mer months pink or pinky-white hibiscus-like flowers are produced in profusion. It grows readily from seed. Although the genus Eucalyptus is veiy widespread within Australia species found near the coast normally grow where some protection is available. Should plants be found right on the coast then they are wind swept and rarely form useful protective bar riers. Two species, however, which are more hardy than others are, first, Eucalyptus cornuta,

KELSHEIMER: NEMATODES 297 ISO NULUAKBOR. PLAINS SOUTH ys AUSTRALIA Map of South Australia showing position of Adelaide Gulfs and Kangaroo Island. "Yate Gum," and, secondly, E. botryoides, "Mahogany Gum." This last is very closely related to the Swamp Mahogany, E. robusta and grows to similar dimensions. E. cornuta forms attractive small trees usually many branched up to 25 ft. high. It has interesting small heads of yellow flowers each of which is covered by a long narrow finger-like operculum. One other genus of plants should be men tioned before closing, namely, Tamarix. Miss Ferguson has listed one or two species but interestingly enough has omitted T. aphyllc (T. articulata) the Athel Tree. This genus un der natural conditions inhabits salty and some times coastal positions. We have found all species of Tamarisk so far introduced into this State will survive under coastal condi tions. The deciduous species, especially T. gallica, will grow in either heavy or light sandy soils, sometimes a few feet above the high tide mark and in pure sand. T. aphylla, the Athel Tree (sometimes erroneously called Athel Pine) grows best in deep sands. It was introduced into Australia from California and has proved successful in some of our arid regions possessing light soil but where copious water is available. It forms attractive trees up to 25 ft. high with greyish-green foliage, and during the summer months terminal tassels of pale pink flowers are produced. This species grows best on sandy soils and if brackish water is present will grow in arid districts. It can be seen from the survey given above that South Australia has a number of useful trees, shrubs and climbers which can be used for coastal planting. Most of these possess salt tolerant foliage which of course is important, but it is only by exploiting these plants can we assist gardeners in these difficult regions. Without protection from wind, salt spray and drifting sand the choice garden plants which gardeners everywhere wish to grow will not be given a chance to survive. NEMATODES INFESTING CERTAIN BULBS, CORMS AND TUBERS E. G. Kelsheimer Gulf Coast Experiment Station Bradenton The study of parasitic nematodes and their effects on plants is a very important phase of agricultural research. But it is only recently that the economic importance of nematodes other than the root-knot type has been recog nized. Occasional root-knot infested gladiolus corms were brought to the attention of the writer over a period of years, but it was not until 1950 on a visit to gladiolus fields in the Hastings area and paper-white narcissus fields near Doctor's Inlet that the problem presented itself as one of major concern. The photo graphs are of some of the infested corms dug in the Hastings and Bradenton area (Fig. 1). Our knowledge concerning this important field of nematology is relatively meagre as yet. Therefore, this report is limited to some ob servations and data accumulated over the past few seasons. It is believed best to present them at this time with the hope that they will bene fit other workers.