A vigorous, shade tolerant, truly evergreen ground cover of neat habit, and resistant to Mid-America's climatic adversities was years ago, only a dream.
In 1934 a dreamer and unusual plant curator from the central Midwest, Dr. Edgar Anderson of the Missouri Botanical Garden in St. Louis, was "browsing" in the far corners of the world. From Europe he brought home many varieties of ivy. Two of those from the Balkans had by 1945 survived here and proved worthy of formal introduction and naming. To one of these Hedera helix of the Ginseng family he gave the name 'MBG Bulgaria} (The MBG comes from Missouri Botanical Garden.)
He had found it growing vigorously in the deep shade of a beech forest behind the Rila Monastery at the head of a valley in the Bulgar mountains. This is a land of rigorous winters and languorous summers. Now for 20 years 'the ivy has been growing vigorously in the Mausoleum grounds near the old Shaw residence of the Missouri Botanical Garden. It remains verdant and live looking winter and summer. As a ground cover it is attractive with its uniform six-inch height and horizontal leaves averaging four inches wide, shallowly lobed, and not prominently veined. Although somewhat denser in deep shade, it stays uniform with no bare spots in areas of light shade and even full sun.
Hardiness of MBG Bulgaria has been severely tested by the dramatic seasonal changes of this area in the past 20 years. Although we have had a wet year, we have not forgotten the preceding five years of drought, nor the previous five of summer rains producing floods and high humidity with accompanying mildew and fungus growths. Well remembered, too, are the alternately mild and severe winters with the extremely cold test of 195152. Old plantings of less vigorous ivy varieties, including most unprotected English ivy, were killed to the ground or severely damaged. 'Bulgaria' came through with flying colors.
Not Pampered
Hardiness to human neglect? If you do not know the Missouri Botanical Garden you might think that ivy is pampered here. Any member of the staff or board will gladly tell you that even the 50,000 orchid plants hanging in their glass houses must learn to live in the environment provided. Ivy is just a ground cover to avoid the trouble of trying to grow grass in difficult areas where the public often insists upon walking. Hardiness to neglect (thus reducing maintenance labor and costs) is one of MBG Bulgaria's finest qualities.
Comparison with surviving old plantings of two other ivy varieties is easily made in the MBG Mausoleum grounds. One of the other ivies is Bulgaria's Balkan sister 'MBG Rumania' introduced at the same time. 'Rumania' is more tolerant of planting in full sun or hot dry places. It has smaller leaves and about the same height but is less uniform than 'Bulgaria.' The other, °Baltic Ivy,' has still smaller leaves, is deeply lobed, prominently veined, and clearly less vigorous than 'Bulgaria.' While all three came through the winter of 1951-52 it has been said that 'Baltic' recovered, 'Rumania' shrugged, and 'Bulgaria' laughed.
This thrifty ivy, green the year around, is an excellent foil for early blooming spring bulbs such as snowdrops. Thousands of these dainty white flowers in February nod above the glossy green ivy carpet at the MBG. The vine also provides a beautiful cloak for stone fences and rough barked trees such as large oaks and elms. It is selective, and does not bother to climb on less majestic carriers. A question of harm to trees is sometimes raised. There is no evidence of it. In England many great trees have gracefully carried their cloaks of ivy for more than a century. 'Bulgaria' is happily clothing the oaks in the Mausoleum grounds at the MBG. On tree as on ground it tends to leave no bare spots, but covers the trunk with velvety green all the way around.
Has Two Forms
'Bulgaria,' in common with other ivies, is dimorphic. That is, it may produce two kinds of leaves, juvenile and adult, 0n the same plant. As long as it creeps upon the ground year after year, it produces only juvenile leaves-never branches, and never flowers. New plants grown from stem cuttings from tips of juvenile vines will creep for several years, even in the presence of something on which they might climb. After three to five years (depending on growing conditions) the vines that are in the vicinity of a possible tall carrier, aroused perhaps by its passing shadow, will start lifting their heads as though in search of a ladder. When they encounter something that might prove suittable, such as a stone fence or a large rough barked tree, they start climbing.
The juvenile leaf form, with its non-branching, non-flowering habit, persists until it has climbed for ten or 20 feet, perhaps another five or ten years. Then these vines, having determined, apparently, that the carrier is a secure place from which to propagate, begin a highly dramatic transformation. They start branching outwardly in a horizontal plane. The leaves change from a lobed to an almost unlobed form. The branches rebranch and develop flowering terminals. Each autumn thereafter, this bushy portion of the vine is covered with small greenish flowers in tight little clusters. Flower petals fall and fruit forms in the shape of berries, about the size of small peas. These are purplish green and are not readily noticeable. They usually cling 0n through winter. In early spring they are welcomed by birds migrating northward.
There is speculation that this migration northward is desirable so far as keeping 'MBG Bulgaria' under control is concerned. Since this ivy came originally from a climate about like that of Little Rock, Arkansas, it is believed it might become too rampant if the birds should carry the seeds much further south. The vine seems ideally controlled in a central mid-America latitude and to points as far north as survival extends.
Flowers and Berries
Because previously introduced varieties lacked long-range hardiness in this latitude, many residents of the central states have never seen mature ivy. It can be viewed now at the Missouri Botanical Garden. Entering through the north gate of the iron fence surrounding the Mausoleum grounds, one passes 'MBG Bulgaria' on both sides of the walk. Shortly, the visitor is passing oaks, pin and burr, on which the ivy is climbing compatibly. At a height of about 15 feet the ivy begins to branch out at a right angle to the trunk and rebranch into a bushy formation. This is mature ivy which will flower in autumn with subsequent fruiting of clustered purple green berries.
Propagation at the juvenile creeping stage is simple from stem cuttings. In spring cut five-inch tips sharply below a node, dip in hormone, stick in pots of damp sand or vermiculite, and set in a north window or under fluorescent light. The cuttings will root easily. Remember, these juveniles cut from creepers will not climb for several years.
Ready-to-climb plants such as the English Ivy can be had from first year starts by taking stem cuttings of vines in the adolescent stage, where they are lifting their heads or have been climbing for five or ten years. Rooting these older stem cuttings requires stronger hormone, careful balance of moisture in the rooting medium, and control of humidity which is best given in a polyethylene tent. An easier way is over-winter layering of a long vine taken down from tree or fence, pinned firmly to the ground and mulched.
Shrub ivy plants can be obtained from cuttings taken directly from their mature branches. Rooting these is similar in difficulty to that of other woody plant material. Best results come from cuttings taken at the peak growing season (July) and rooting them by mist propagation. Plants from these mature branch cuttings do not creep or climb. They grow upright from the start. They can be trimmed into low edgings for bordering walks, shaped for hedging, or pruned to specimen bush form. Where advanced shrub forms may be seen I do not know, but having made a start, I confidently anticipate having something interesting in five, ten, or 15 years.
