Bulletin of the American Rock Garden Society Volume 48 Number 4 Fall 1990 Cover: Gaultheria humifusa Painting by Carolyn Crawford, of Louisville, Colorado. A photograph by William Jennings served as her model. Bulletin of the American Rock Garden Society Volume 48 Number 4 Fall 1990 Features Genistas Perform in the Rock Garden, by Phyllis Gustafson 243 Planning an Expedition, by Don Hackenberry 249 Berries: Not just for the Birds, by James Cross 261 The Pawnee Buttes, by Geoffrey Charlesworth 267 Fall Bulbs for the Rock Garden, by Judy Glattstein 273 Moraine Construction, by Ray Radebaugh 285 Departments Books 297 Awards 305 242 Bulletin of the American Rock Garden Society Vol. 48(4) Genistas Perform in the Rock Garden by Phyllis Gustafson As I sat looking out the window the larger rock garden. The others on a cold winter morning, the sun are all small enough for troughs, or in was shining on the garden, playing very special places in crevices, or tiny up the forms and shapes of those rock gardens. stalwart individual plants that are the In the vast family of Leguminosae backbone of the rock garden. These (peas, to us gardeners), there are are the small conifers and shrubs that almost 500 genera. Of these, about in midwinter are a symphony of 100 are in cultivation. The genus profiles and textures that make the Genista, with about 80 species, is garden a graceful dance for the eyes. considered one of the most important To create a rock garden, or any for use in all types of flower gardens. pleasing work of art, you must bring However, I have found that only into being patterns of motion. This about 20 species have been listed in motion is the movement of your eyes seed or plant lists or rock garden as you view the art. In the rock books. These few have been through garden, the motion is guided by the the lumping and splitting of taxon- points of interest, and these change omists and are listed by different with the seasons. In midwinter, plants authors under diverse species, or in their winter dress create this even generic names. Being a garden• motion. er who would rather grow the plants Certainly, some of the small than learn new names, I will use the genistas can not be beat for interest• names that are best known. ing textures and shapes! Each species All genistas thrive in well-drained, has its own peculiarities and looks light, nutrient-poor soil. Because they very different from the others. Of come from western and Mediter• those I am now growing, G. horn- ranean Europe where the rainfall is da, G. lydla and G. tinctoria are sparse and the long summers are hot appropriate as points of interest on and dry, they are the ideal choice for 243 Unfortunately, in the dry summer climate of southwest Oregon, I do have to keep a constant watch for red spider mite, one of our worst garden pests. This little arachnid can cause much damage before the gardener even realizes it. The leaves will turn a blotchy yellow and, in the case of G. horrida, this so weakens the leaves and stems that whole branches will die. The mites are specks of red so fine that they are hard to see with the naked eye. You can use a hand lens, or knock the stems against a piece of white paper, or, as I often do, just run your fingers gently over the leaves and stems and see the little fellows on your hand. In our dry climate, they are encouraged by dust settling on the leaves. A good, strong wash of the water-conscious gardener. If not water will slow them down, but I have covered in colder climates or during found that this is not very effective cold snaps in zones 5, 6, and 7, unless done every day. Since constant some of the more tender species will hosing is not practical, I have found suffer from frost damage. They do insecticidal soap a big help for late recover with remarkable speed once season attacks. If I see the mites turn• spring arrives. ing G. horrida a pale, lusterless color Genista horrida (Echinospartium early in the summer, I use a systemic, horridum) is at center stage of the which will last for two months or garden from my window. At 20 years more. I feel this is less damaging to of age and only 15" tall and 30" the environment of the garden than wide, this light olive-green, spiny frequent spraying with contact insecti• shrub stays a compact dome that cides. When these early attacks never needs pruning. Told that it occur, I look up. The willow tree came from hot, dry areas of Spain nearby is often attacked in late May, and Portugal, I placed it in full sun in and then the red spider mites rain very lean soil. The small heads of down on all plants below for the rest bright yellow flowers, which do not of the summer. The problem has bloom until June here, are followed been almost curtailed since the tree by seed. Seed is perhaps a good way has been injected with systemic insec• to grow more plants, as cuttings do ticides in midspring for the last two not always strike, even if you are years. This not only helps the tree, careful to take green, growing wood. but also all the plants in the yard and (Spines alone, easy to confuse with does not hurt birds, insects, nor us. the stems, cannot root.) In the large rocks in front of the 244 Bulletin of the American Rock Garden Society Vol. 48(4) house, G. /ydia's mass of arching, almost leafless stems come billowing from her center like a bird's nest fern X^sjy (p. 304). At 12" in height, she always commands attention. With age, this 1 genista from the Balkans can become ii[ 5' or more across. In late April she completely covers herself with flow• % ers. She seems to never be bothered by insects and strikes easily from cuttings; therefore I now see G. lydia performing at the local Burger King and at the shopping mall. Even so, I will not become a snob; she shall \f stay at the front corner of the rock garden to act as a barrier to dogs and \\ small children and to delight the curi• /Eij w ous along the sidewalk. W\ Genista sagittalis On the highest point of the front \ rock garden, G. sagittalis {Cham- aespartium sagittate) flops over the comment with its strange flat stems, large granite rocks. The cladophylls reminding me of a heap of half-inch are straight when young but they ribbon tied on top of a birthday twist and turn as they age. (A clado- present. phyll is a flattened, leaflike stem that Genista pilosa is widely distributed has the form and function of a leaf, throughout Europe, and there are but arises in the axil of a minute, many cultivars. Genista pilosa bractlike, true leaf.) They are a 'Procumbens', at 2" in height, is a wonderful, rich green color all year favorite of landscapers. It can grow to but in spring the new growth is a 3' across and is one of the heaviest deep citron. The typical yellow pea bloomers. The University of British flowers in tight corymbs at the ends Columbia Botanic Garden has intro• of the stems are the richest color of duced a superior form named any in the family. To my eye, this 'Vancouver Gold' (p. 302). While I color combination is a feast. The grow it in the crevice garden where it plant is only 6" high but in 14 years shapes itself to the rocks, it is consid• has become 4' across (p. 302). ered the perfect ground cover. From France, G. delphinensis In a crevice, at the edge of a walk, [Chamaespartium sagittate ssp. sits G. dalmatica (G. syluestris v. delphinensis) is a tiny version of the pungens, p. 301). This little-known plant described above, staying under plant is an ideal subject for the front 3". It prefers neutral soil. Too small to of the rock garden, or even for a be a point of interest in the rock large trough, as it is only 4" high. garden, it is just right for a small Genista dalmatica, also too small to crevice or a trough. It always causes be a point of interest, is the most deli- Genistas 245 which variety humifusa, only 2" high and very prostrate, is another fine \\V choice for troughs (p. 303). With its shiny leaves held flat to the ground, straight stems radiating out from the S^U' center of the plant like the spokes of \ a bicycle wheel, it looks very different >3 from the other small genistas. My favorite genista, G. villarsii b*\Lt \ (G. pulchella, p. 304), is a 2" mat of T ^. yfi 1 sli v. whipcord stems. The gnarled, warty ^"^S^SjMf'c ij** stems will occasionally root into the 1 iJSii Jr+ ground, affording one method of TJC? propagation. It puts on a fine show of 1 heavy bloom with loose racemes in k June and is a delightful tangle the rest Genista dalmatica of the year. Genista villarsii, from southeastern France and Albania, is cate looking of the genus, with fine also in my crevice garden where it stems, tiny leaves, and sliver-fine enjoys the full sun. spines. The tops of the stems are With the exception of G.