ROCK GARDENS

New Zealand Journal of Agriculture, Volume 98, Issue 3, 16 March 1959, Page 301

ROCK GARDENS

By

K. H. MARCUSSEN,

Horticulturist, Department of Agriculture, Christchurch

HOME gardeners confronted with making a garden on sloping II ground often consider the development of a rock garden. However, such a garden can also be made on a flat section and will then be particularly attractive by creating a change in the general layout. Selection of a suitable site and the fundamentals of construction and establishment together with the general cultivation and maintenance required are dealt with in this article.

ROCK gardens and alpine gardening fascinate many people, probably because most of the plants used are small and each one has its own charm. Furthermore, rock gardens can be made to suit any size of garden, varying from a few. yards square to the large and boldly laid out ones in parklike gardens. In the past rock gardens were sometimes made of heaps of rocks with the rocks placed too close together; plants were then frequently struggling for existence in the small .spaces available for them. Fewer rocks are used nowadays and results .are more pleasing with the plants .growing under more congenial •conditions. True alpines will not grow satisfactorily in some of the warmer districts, .particularly where humidity is high,

but many dwarf plants which will give a pleasing display can be substituted. Site The best site for a rock garden is a slight slope facing north, in the open, and with good drainage. Most rock garden plants, particularly alpines prefer full sun; hence the preference for a northern slope. Some grow better in partial shade, but this can be provided readily on a slight slope, where such plants can be set on the

southern side of large rocks which will give the shade they need. This cannot be done so easily on a steep slope, where the height of the rockery may not be sufficient to create shade in a natural manner. A rock garden should be in the open mainly because the plants require full sun. Large trees in the vicinity will throw shade at some time, except if they are on the southern side. Even there they should be far enough away that no branches overhang, not only because of shading, but because water would drip from them during wet weather. Rain usually is beneficial, but drips from overhanging branches can be very damaging,, as the drops often fall continually on the same spot. Roots from . trees growing close by can also cause trouble by depriving the rock garden plants of both moisture and plant food. Even certain types of hedge plants and shrubs can be detrimental and should be used in the vicinity with discrimination. Most rock plants, particularly alpines, need perfect drainage. Where

they are growing naturally they may at some time of the year be subjected to much moisture round the roots, for example, when snow is melting, but the nature of the soil in which they are growing will facilitate immediate run-off. Without good drainage most alpines will soon succumb. Lawn approaches are very suitable and the addition of one or more pools, according, to the size, will greatly enhance a rock garden, particularly when a running stream, possibly with small waterfalls, is incorporated in the layout.

Rocks A rock garden is sometimes developed round a rocky outcrop and there is then no question of selection of site. More commonly, however, the rocks are brought to the site. Such rocks should be selected, not just ordered from a quarry, and though cartage cost usually necessitates the use of stone which is available in the district, some discrimination as to type should be made. The rock preferably should be weathered and if it is possible to obtain stone with lichen growing on it, so much the better; the rock garden will- then have an established appearance as soon as it is made. Hard rock should be avoided, as it seldom blends into the surroundings. Broken porous stone is not suitable either, as it tends to crumble, particularly in districts which experience hard. frosts. If this stone has to be used, the hardest surface should be placed uppermost to overcome deterioration. A rough type of stone is most suitable, as it provides good growing conditions for the plants and if it is fairly soft, it will weather quickly and any marks made during construction of the rock garden will soon disappear. Limestone and volcanic rock are the best types available. Limestone, however, should be well weathered before use, as otherwise it may make the soil too alkaline. The rocks should be large, though in proportion with the size of the rock garden and the whole flower garden area. It is very difficult to make a worthwhile job with very small stones. • Construction and Layout The first step in making a rock garden should be to plan the layout in as much detail as possible. This cannot be done in the same manner as for other garden arrangements, but it

is essential to . have clear thoughts on what is to be done. The various sections of the rock garden should be readily accessible, especially if it is large, as otherwise maintenance tends to be neglected. Paths should therefore be pegged out at an early stage, though their final position may be rearranged as the work progresses. The main features should be decided on and the work begun on these; the

surrounds can be built up afterward to suit the particular characteristics. Rocks must be close together on steep slopes to prevent the soil being washed away, but the rocks should be grouped together on gentle slopes in a manner in which nature might have left them. On a rocky hillside you can find some rocks close together, then perhaps odd ones here and there, and again other groups of them, their occurrence being very irregular. This should be the aim in the layout of a

rock garden instead of having the rock scattered indiscriminately throughout the area. Where different types of rocks must be used the various groups should consist of different-sized rocks and these should be matched as much as possible within the group. For instance, in natural conditions a piece of granite would not be found among limestone. On a sloping section the layout is fairly simple, as generally the contours will be followed; in some instances, such as on steep slopes, the grade may be the deciding factor in the arrangement. On flat sections, however, the rock garden should be placed so that it becomes part of the whole garden and blends into the surrounds. The height should therefore always be in relation to the size of the base. The rocks should be placed firmly. Large rocks should be sunk well into the ground so that they will not move later. They may have to be wedged into position on steep slopes; in fact, a construction in the nature of a dry stone wall is sometimes, required. It

should be kept in mind that children always find delight in climbing over rocks, and hidden dangers to them should be guarded against. i Soil After construction of a rock garden, particularly on a hillside, the available soil is often found to be poor and sometimes very heavy. It already has been stressed that good drainage is essential for rock garden plants and any improvements required must be made before planting. Improvement to the soil will have to be done according to. the type of plants which are to be grown in any particular position. For true alpines it is generally desirable to open the soil up with coarse sand and chips, thereby making the soil comparable to that of their natural habitat. For the coarser types of rock plants, those which are often grown in the mixed border, it will be more beneficial to incorporate decayed organic matter such as compost; this will improve the water-holding capacity of the soil and make additional nutrients available.

Care should be taken to ensure that the soil is well packed round the rocks and that there are no air pockets. The addition of lime to the soil must be governed by the kind of plants it is intended to grow. Selection of Plants The selection of plants will depend largely on the size of the rock garden. Subjects which are fairly compact and do not spread much should be chosen for small areas, but bigger and more vigorous types of plants can be used for larger ones, where dwarf trees and shrubs also may be used. Small subjects give a better display when several of the same kind are grouped together; this should be allowed for when space permits. Alpine plants flower mainly in summer, but other types of plants can be used to provide colour throughout the year. There are many small bulbous plants which are colourful during late winter and spring. Some even flower in autumn. Herbaceous plants can also be used to extend the season and many are now available in dwarf forms; small evergreen shrubs and dwarf coloured conifers are always attractive. . . . [Elliott

The list on this page gives a range of plants which are useful for rock gardens and the positions for which they are suitable. Planting The main planting of rock garden subjects should be done in autumn or spring. In many North Island districts it can also be done during most of the winter, but winter planting is not advisable where hard frosts are experienced. Some specialist growers supply rock garden plants in pots and such plants can be planted out of season, but special attention should be given until they are established. Bulbs should be planted at the appropriate times for the .individual kinds. The soil should be moist, but not too wet. The roots should be spread out well and soil packed among them. Plants which have been growing in pots should have the roots slightly teased out at the bottom, and any consolidated soil round the top of the plants should be broken to allow better entry of water. Any which appear to be pot bound should have the roots gently eased out round the whole ball to encourage them to grow into the new soil. Usually the crown should be planted at soil level; any exceptions from this can be noted on the plants when they arrive. Too deep planting is generally harmful.

Plants set out in spring may need watering. Any extra attention given at planting time will prove well worth while later.

General Attention

During the first year or two the main attention to a rock garden will be to ensure that plants are establishing and are in a suitable situation. That may not always be so and it is sometimes wise to lift unthrifty plants and shift them into other positions, where they will. get more or perhaps less sun, or into a different soil mixture. Such shifts, however, should be made at an appropriate time and . generally not in the middle of summer. Weeds must be removed as they appear. Some rock plants are very small and can easily be smothered, so weeding should be done frequently. It will be beneficial at the same time to stir up the soil between the plants with a small fork or cultivator. Watering should be done as required; once established, rock garden plants, in common with other garden plants, should be given a periodic soaking in preference to frequent light hosing. Most of the plants will require further attention when the rock garden has been established for a few years. Vigorous kinds that tend to spread should be kept within bounds. Some may become rather bare in the centre with vigour showing only in the new growth on the outside of the clumps. Cutting back may rectify these defects or it may be better to replant. Sometimes shoots will have layered and can

be used for replacements, or cuttings can be made, the latter being the method usually employed by nurserymen. Others again seed freely and the resulting seedlings make the clumps too crowded and some thinning out may be required. The aim should be to keep the plants growing well but not so vigorously that they become crowded. Some topdressing with good friable soil mixed with compost or sand is necessary from time to time, especially where soil has been washed away and roots are exposed. Fungous diseases seldom cause much trouble in rock garden plants, though various insect and soil pests often do. Greenfly (aphids), thrips, and mites may build up if not controlled, but these can be dealt with readily with malathion. For a bad infestation, two or three applications should be made at fortnightly intervals. Malathion, DDT, or lindane can be used against various caterpillars. Woodlice (slaters) sometimes become numerous; they are best checked by generous use of 2 per cent DDT dust in the places where they congregate. Snails and slugs are probably the greatest problem and many of the best dwarf plants may suffer severely if they are not kept under control. The nature of the plants grown and the shelter afforded by the rocks provide slugs and snails with ideal conditions. Metaldehyde in a ready-mixed bait should be placed near their haunts, or a liquid form of metaldehyde can be sprayed on to the plants and the ground. Garden Work for April

With the colder weather and the beginning of frosts in some districts many plants take on an autumn appearance as leaves colour and begin to fall. During cleaning up it will

be necessary to burn any diseased material, but healthy plant material should be composted. Formal Beds Tuberous begonias should be lifted from their beds and placed in wooden trays in a dry, frost-free place to dry

off gradually. The tops should not be cut off but should be allowed to die

down naturally. For colder districts the same treatment can be given to fibrous-rooted begonias and geraniums. In warmer areas these will store satisfactorily under a hedge or similar shelter. Calendulas, French marigolds, and other annuals should be removed and the beds prepared for replanting. Iceland poppy plants, which are now available in good pastel shades as . well as brilliant scarlet and orange, should be planted early this month. Polyanthus, of which there are many fine strains, can be planted out. Old plants selected for their quality can be broken into sections and replanted. In frost-free areas cinerarias will give a good display if planted 15 in. apart in good soil. The crowns of these plants should be above soil level when planted out to discourage fungous rot. Primula malacoides, calendula, pansies, violas, beauty stocks, Bellis perennis, wallflowers,' and sweet william are some of the most reliable plants for a spring display. Sweet william is now available in a variety of colours in a dwarf size for edging as well as the 15 to 18 in. high type. For the Mixed Border Six weeks after blooming, gladiolus plants can be lifted with the cormels attached and dried off in boxes placed

out of direct sunshine. When dahlias have been cut by the frosts the tops should be cut off 6 in. above ground level. They should not be broken off, as the buds for next year’s growth may be damaged. These buds lie at the junction between root and stem. Where frosts are not heavy dahlias can be left in the ground over winter, but where frosts are severe they should be lifted and dusted with DDT before storage. Any diseased or distorted plants should be burnt. Annuals, biennials, and other plants which are past their usefulness should be removed. Areas of the border can be replanted as space becomes available. The planting of clumps of bulbs in the spaces should be hastened. The soil can first be improved by the addition of compost. Bulbs, including iris, ornithogalum, ixia, and tulips, can be planted. In the north tulips should be kept in a cool place until conditions become cool enough for planting. Snowflakes (which have several flowers on a stem) and snowdrops (only one flower per stem) can be planted. The foliage of Iris unguicularis (I. stylosa) should now be cut oack to within 4 to 6 in. of the ground. This, with a dusting of DDT, will discourage slaters and slugs, which can damage the flowers. Border Plants Plants such as Canterbury bells, gaillardias, perennial scabious, aquilegia, delphinium, and lupins can now be planted out in groups in the border. The different colour markings, ease of growth, and number of quality blooms borne on stout stems make gaillardias excellent border plants. Cynoglossum amabile, which produces large sprays of forget-me-not like flowers during spring, can be planted now among shrubs in a well drained position where it often naturalises quite freely. Hardy annuals, including clarkia, cornflower, nigella, calendula, godetia, and larkspur, can be sown in warm borders to become established before winter and give flowers in early spring. Seedlings of annuals sown where they are to flower should be thinned as sbon as possible, as if overcrowded they will develop into spindly plants which will give a quick but short flush of spring flowers. Carnations can be planted out and large clumps of pinks can be lifted and divided. Rooted layers of border carnations can be planted out in an open, sunny border. Rockeries and Banks Bulbs are well suited for planting in pockets of soil on rocky banks or slopes and, with succulent plants, can make such areas very colourful. Fritillaria imperialis, the Crown Imoerial, does best under cool soil conditions and the fleshy bulbs should be replanted as soon as possible. If the bulbs are damaged, sulphur or thiram should be dusted on the wounded surface before planting.

Chionodoxa (glory -of - the - snow) galanthus (snowdrop), crocus, tritonias, and freesias are showy plants for such situations. Galanthus and chionodoxa should be labelled so that the bulbs of these plants, which multiply slowly, are not lost. Plants of Sedum spectabile Brilliant can be planted in the heavier rockery soils, where it flowers for a long period during summer. In the warmer districts Billbergia nutans, with its stately pink stem up to 18 in. long and green flowers in spring, can now be planted out. The closely related Beschonaria yuccoides, which has a spectacular red stem up to 8 ft. high, can be planted in barren, rocky positions in full sun. Plants from Cuttings Many shrubs and trees can be propagated by hardwood cuttings taken at this time. Results are often disappointing when the cuttings are not taken until later when the deciduous plants lose their leaves. Cuttings taken now should form a callus area, from which roots later develop, at the base of the cutting before the ground becomes too cold. Cuttings of evergreen material, including conifers and hedge plants, should be 6 to 10 in. long and the leaves should be removed from that portion of the stem which will be below ground. Cuttings of roses, forsythia, flowering currant, jasmine, or honeysuckle should be 10. in. long. If suckering or basal growth is undesirable, as with rose stocks, the bottom buds should be removed before cuttings are inserted firmly up to half their depth in sandy soil. Cuttings of perennials such as Jerusalem sage (Phlomis), perennial wallflowers, marguerites, calceolaria, verbena, and pentstemon can be placed in a cold frame ready to root during winter and will be ready for spring planting. Plants for Shady Positions On the south side of the house, where little sun penetrates, quite a good range of material can be planted. Two old-fashioned plants which are regaining favour are Solomon’s seal, with its graceful stem of white bells beneath, and bleeding heart, with its quaint pink and white flowers. These two can be left undisturbed for several years. Thalictrum dipterocarpum, astilbe, and aquilegias are all very useful for picking. Newer varieties of aquilegias combine many lovely colours. . Two bulbs which could be planted now in this position are Fritillaria meleagris (snake’s head) and dodecatheon. Both need a gritty soil to which generous amounts of compost have been added. The crowns of convallaria (lily of the valley) and bulbs of erythronium (dogstooth violets) can be planted under similar conditions.

With large specimen trees half the tree may be wrenched one year and the other half early in the year of transplanting. Cleaning up and Lawns Dead leaves should be raked up and placed in the compost bin; a Large quantity could be stacked separately. The leafmould so formed is useful as a mulch or in potting mixtures. If leaves are left lying on lawns, the grass becomes yellow and rotting may occur in the lawn owing 'to poor aeration. Any twitchy lawn growth or moss can be raked at the same time. ; The twitch growths should then be mown against the direction of the raking. If lawn areas have become lifeless through heavy summer compaction, they could be aerated by pushing in a fork to full depth and levering back the handle to lift the soil slightly before withdrawing the fork.

Cinerarias will grow quite well with little sun and should be planted early this month in frost-free positions. Trees and Shrubs Orders for trees, shrubs, and hedge plants should be placed as soon as possible and preparations for planting begun. In deep, rich loams little preparation will be necessary, but in gardens on poor soils or being developed on rotten rock or stony soils preparation for planting will be necessary for most plants. Some of the South African plants, such as proteas and leucospermums, do not appreciate the incorporation of organic matter, but otherwise holes can be dug out to a depth of 2 ft., the subsoil forked, and compost plus a dressing of bonedust'mixed with the soil before it is replaced. Plants which are to be transplanted later should be wrenched. This entails the cutting of the roots, the depth depending on the size of the plant.

As plants fade the stakes supporting them should be removed and washed under the tap to remove the soil before they are stored. Dipping the ends in creosote or other preservative will prolong the life of stakes. Replenishing Window Boxes Of the annuals mentioned for bedding, calendulas are probably the most reliable for window boxes. If the boxes are small, the soil may need replacing each time the box is replanted. The size of the box will usually be a compromise between the desirability (mostly for labour reasons), of having a large area of soil and the elegant appearance of the box. It is undesirable to have too much bare board showing and a depth of 9 in. is usually satisfactory. Glasshouse Work Begonias will be passing their best display and water should be gradually withheld as they dry off. When the

tops have shrivelled the tubers can be knocked out of their pots and most of the soil removed from the roots. The tubers should be dusted thoroughly with flowers of sulphur before being placed on a tray of dry sand for storing. Bulbs for flowering in bowls can still be potted up and placed in a cool position for 6 weeks while the roots develop.' Bowls which were prepared earlier may be ready to bring into a cool room. They should be watered sparingly at first. After a dry, dusty summer most foliage plants require to have the leaves cleaned with a sponge. For shiny leaved plants the addition of summer oil to the water freshens the

foliage and will clean up any scale insects or mealy bugs present. Fuchsia plants can be allowed to dry out . gradually to rest the plants. Geraniums and balsams can be pruned back hard to encourage new shoots. Seed of many glasshouse flowering plants, such as schizanthus and calceolaria, should be sown. General In mild districts hydrangeas can now be pruned and sweet peas sown. The ties on budded roses should be examined and cut as the buds begin to swell. Gladiolus corms with rotten patches or scars should be discarded. Any. valuable corms with slight areas of

infection can be treated individually, however, by cutting out infected areas and dusting liberally with sulphur. They should be stored and subsequently planted separately from sound bulbs. All bulbs should be dusted with DDT and flowers of sulphur before being stored in a dry, cool, airy, and frost-free place. Chrysanthemums will give larger blooms if disbudded early. A soluble foliar fertiliser given now will be beneficial. Late-flowering varieties need to be covered if they are to flower outside in frosty districts.

TTj 1 Ft O I i I Book' Review I gf UUXLJLI 11MAJLJUJJJ1_> “Designed Flower Arrangement”: Margaret O’Brien r ipHE author of this well printed and A attractively designed publication is obviously a painstaking enthusiast who is determined that her readers shall have a thorough appreciation of all the factors necessary for successful flower arrangement. In eight chapters, seven of which originally appeared in “The New Zealand Journal of Agriculture”, she has given much useful information, which might best be indicated by the chapter headings: Flowers as an Art Medium; Possibilities of Containers; Informal Line Designs; Formal and Mass-line Designs; Table and Wall Designs; Colour in Plant Material; Dried Flowers for Winter Use; and Amateur Flower Arrangement Shows. Though line design is a very important factor in successful flower arrangement, to the real enthusiast and the average woman alike probably the most interesting aspect is the colour factor,, and perhaps the most engrossing contribution of this book is its detailed explanation of colour complexities and the drawings of a colour chart and colour wheel, both in full colour. Masks for the colour wheel and detailed instructions on use of the wheel are included. As the book is printed on very good paper with many excellent illustrations, it seems a pity that one or two of the more spectacular arrangements illustrated were not reproduced as full-colour, full-page pictures. The book can be recommended not only to the confirmed enthusiast but also to the average . woman who likes flowers throughout her home, but has not the knowledge that would enable her to achieve much better effects.

Plants for Sunny Places Cotyledon species Arabis albida and other Crocus species species ' Achillea species • ★Cyclamen neapolitanum Aubrietia deltoidea Aethionema species Cypripedium species varieties ★Allium species . Daphne blagayana Borago laxiflora Androsace species Daphne cneorum Calandrinia umbellata Antennaria dioica [Deutzia gracilis Campanula species Arabis albida Epimedium alpinum Cotoneaster adpressa Arenaria species [Erica species [Cotoneaster congesta Armeria maritima *Eranthis hyemalis [Cotoneaster horizontalis Armenia alpina *Fritillaria species [Cytisus keuensis Aster species and varieties [Gaultheria hispida Gaultheria nummularioides Aubrietia deltoidea and ★Hemerocallis species ■ Gaultheria procumbens varieties *Leucojum autumnale Linaria cymbalaria [Berberis darwini nana Meconopsis betonicifolia Lithospermum prostratum ★Bulbocodium vernum ■ var. baileyi Mimulus radicams Campanula species Mimulus species Nertera species Oelmisia species [Mitraria coccinea Polygonum affine [Ceratostigma plumbaginoides Nertera depressa [Rosa pendulina and var. [Oeratostigma willmottianum ★Ornithogalum umbellatum pyrenaica [Cistus species Ourisia species [Rosmarinus prostratum ★Colchicum species Primula littoniana and Sedum species ’ Crocus species other species . Thymus species [Cytisus procumbens Ranunculus species [Cytisus pzirpureus Thalictrum alpinum Dianthus species and Trillium grandiflorum varieties Viola species Dicentra species Dwarf Trees and Shrubs ★Galanthus byzantinus ~ ★Galanthus elwesi . ' Abeba floribunda [Genista species Acid-intolerant Species Abies picea nana Gentiana acaulis . . . Andromeda species Gentiana corymbifera Achillea species Betula nana Gentiana pneumonanthe Aethionema species Cassima fulvida Gentiana saxosa Alyssum montanum Chamaecyparis lawsoniana Gentiana sino-ornata Alyssum saxatile ■ minima glauca and other species * A.n-emo'ne alpina Chamaecyparis obtusa Geum species ★ Anemone pulsatilla nana Gypsophila species . Aquilegia species Daboecia species [Hebe species [Cistus species . Erica species & elianthemv/tn chamaecistus ★Cyclamen species Junvperus communis (vulgar e) varieties Gentiana species (dwarf varieties) Helichrysum species Gypsophila species Kalmia latifolia ★Hyacinthus azureus Lithospermum gastoni Magnolia stellata . Hypericum species Papaver alpinum Picea glauca conica Iris innominata Papaver nudicaule Picea orientalis nana ★lris reticulata Phlox subulata Pernettya mucronata Iris unguicularis (stylosa) Primula (most alpine Rhododendron species and and other species species) . varieties including Lithospermum species Sedum species azalea Mazus radicans Sempervivum species Spiraea bullata [Magnolia stellata ' *Sternbergia lutea Thuya occidentalis Me'sembryanthemum species ★Tulipa species ericoides Morisia hypogaea Wahlenbergia saxicola Thuya orientalis sieboldi ★Muscari azureum Zenobia pulverulenta ★ Narcissus species Nepeta species ’ . Nierembergia species Lime-intolerant Species Papaver alpinum . , Phyteuma species [Andromeda species Bulbs and Other Species tßhododendrons of the ★Anemone sulphurea with Underground or R. calostratum series * Anemone nemorosa Ground-level Perennating , [Rosa dwarf species [Daboecia cantabrica Organs [Rosmarinus prostratum [Daphne alpina Saponaria species Daphne cneorum Allium species Saxifraga species and . [Erica species (except Anemone species varieties E. carnea) Chionodoxa luciliae and ★Scilla sibirica [Gaultheria hispida other species Sedum species Gentiana sino-ornata Colchicum autumnale Sempervivum arachnoideum [Kalmia latifolia Crocus species and other species Lithospermum prostratum Cyclamen cow, Silene species Meconopsis betonicifolia Cyclamen europaeum Statice species var. baileyi Cyclamen neapolitanum ★Sternbergia- lutea [Pernettya mucronata Fritillaria species Teucriwn species [Pieris species Galanthus species Thymus species Primula (some species) Hyacinthus azureus ★Tulipa species [Rhododendron (most Iris species Vernnioa queries species and varieties Leucojum vernum tv Ay , P. including azalea) Muscari azureum Wahlenbergia saxicola * Narcissus bulbocodium Zauschneria cana Narcissus cyclamineus '' ' Narcissus minimus Creeping or Trailing Species Narcissus triandrus ■ . . Scilla bifolia and varieties Plants for Shady Places Achillea species Scilla sibirica . , . . Alyssum montanum Scilla verna Anemone species Alyssum saxatile ■ Tulipa clusiana Aquilegia species Androsace species Tulipa fosteriana Auricula species Antennaria dioica Tulipa montana ★Chionodoxa luciliae Antirrhinum asarina Tulipa sylvestris Ootula species Antirrhinum glutinosum and other species

By ROSALIE A. CAMPION, Horticultural Instructor, Department of Agriculture, Wellington

A. H. and A. W. Reed,

Wellington,

New Zealand, 1958. 15s.

* Bulbous plant or one with a ground-level or underground perennating organ, t Dwarf tree or shrub.