By Joshua Siskin
Imagine a plant that produces fragrant flowers and edible fruit, grows in sun or shade, tolerates cold, heat, wind, and ocean spray, requires a scant amount of water and never needs to be fertilized. As if this were not enough of a resume, it also makes a fine hedge, and may be kept at any height between four and fifteen feet.
The plant in question is Elaeagnus pungens, commonly known as silverberry or thorny elaeagnus.
If you are unfamiliar with the silverberry, you may walk right by it, wondering at the mysterious source of the delightful scent which bewitches your nostrils. The species is not remarkable for its beauty, its leaves a drab olive green on their upper side and tan below. There are brown dots all over the leaves, giving the plant a sickly look that is without justification since it is inordinately resistant to diseases and insect pests; these dots are merely part of the leaves' natural pigmentation.
Elaeagnus pungens is a sort of Abraham Lincoln of the botanical world. Its outstanding character traits impart to its homely appearance an air of inexplicable dignity.
One of the most fascinating aspects of Elaeagnus is its physiology. It lives in symbiosis with soil bacteria that form nodules in its roots. These so-called nitrogen-fixing bacteria take nitrogen out of the air and combine it with oxygen to form nitrate -- the same nitrate that is found in most store bought . In return for the nitrate they provide, these root-dwelling bacteria receive carbohydrate manufactured in Elaeagnus leaves that is transported down the length of the plant. This kind of symbiois, incidentally, is also found in leguminous or pod forming plants -- including peas and beans, wisteria vines, acacia, mesquite, and coral trees. Plants that live in symbiosis with nitrogen-fixing bacteria do not require fertilization and are used throughout the world in infertile, nitrogen poor soils as sources of food and fuel. Self-fertilizing acacia trees are used for reforestation of ecologically ravaged areas in South America, Africa, and Asia.
Because Elaeagnus promotes the growth of nitrogen-fixing bacteria, it makes an outstanding companion plant in the garden, landscape, or orchard. The plants that grow around it will have their fertilizer needs reduced and be more productive than otherwise. Elaeagnus may significantly improve yields from nitrogen-greedy plum and nut trees, for example, when it is interplanted among them.
Do not prune elaeagnus between the time it begins to flower, in the fall, and the spring. Pruning during this period will remove the developing berry-like fruits. Both the fruits and the seeds of Elaeagnus are edible. Before consuming seeds, however, you will want to remove their fibrous covers. Elaeagnus makes an excellent container plant. It will waft its fragrance over your patio or balcony each fall, requiring a minimum of maintenance the rest of the year.
Rich Morris, who writes for a permaculture (permanent agriculture) group in England, extols Elaeagnus as a plant for the future. It is among a list of edible ornamental perennials -- including daylily, campanula, violet, and rose-of-Sharon -- that make him wonder "why on earth people fell into the trap of growing annual crops (grains and vegetables) . . . Sitting on a coach on the way home from London," he writes, "I was eating a meal that included roasted chestnuts. Opposite me were a couple of people eating sandwiches. I started to think about the different, but nutritionally similar, foods we were eating.
"I thought about the work involved in growing, harvesting and utilizing each of these foods. With the sweet chestnuts all you have to do is come along in the autumn and harvest the seeds. The plants will continue to yield for possibly hundreds of years without any help from you. With the wheat that is made into sandwich bread, however, it is quite a different matter. Here the ground must be cultivated every year in order to prepare a seed bed; the seed must then be sown; a method found of controlling the weeds; fertilizers added in order to achieve satisfactory yields; fungicides and insecticides applied in order to control pests and diseases and then large machinery used in order to harvest the crop. This is all so much extra work, particularly when you consider that, even with all this effort put into growing it, the yields of wheat will still be less than the yields of chestnuts could be from the same ground."