Phytolacca dioica, Ombu, Bella sombra, Elephant Tree, Bella Umbra, 20-100 seeds
Common names: Ombu, Bella sombra, Elephant Tree, Bella Umbra
Bella sombra is a fast-growing and long-lived evergreen tree with a domed crown, that can grow from 10 - 25 metres tall. The stout, erect bole is 80 - 160cm in diameter at breast height.
It is uniquely swollen at the base, which may grow to 4 metres in diameter, spreading above the ground so that the tree appears to be standing on a mound. Because it is derived from herbaceous ancestors, its trunk consists of anomalous secondary thickening rather than true wood. The trunk and branches contain up to 80% of water. Thus, the ombú grows fast but its wood is soft and spongy enough to be cut with a knife. These properties have led it to be used in the art of bonsai, as it is easily manipulated to create the desired effect. It is sometimes grown as an ornamental plant, capable of providing an excellent shade in areas where other trees will not grow.
Occurrences in Europe. Introduced in France (incl. Monaco and Channel Islands but excluding Corse), Greece, Spain (incl. Andorra but excl. the Balearics), Sicily and Malta. www.maltawildplants.com/
Tree grows best in areas where annual daytime temperatures are within the range 18 - 32°C, but can tolerate 12 - 38°C. When dormant, the plant can survive temperatures down to about -5°C, but young growth can be severely damaged at -1°C. It prefers annual rainfall in the range 800 - 1,500mm, but tolerates 600 - 5,000mm. An easily grown plant, succeeding in most soils, though preferring a moisture retentive fertile soil in full sun or partial shade. Prefers a pH in the range 5.5 - 7, tolerating 5 - 7.5. Established plants are very drought tolerant. Tolerant of coastal salt spray and strong winds, including hurricanes. Plants can be grown in quite coarse grass, which can be cut annually in the autumn
Young trees establish well and grow away quickly - they can easily reach a height of 4 - 5 metres in two years.
An aggressive plant to grow in gardens, it has root suckers that appear readily above the soil.
No pre-treatment is required. Best sown as soon as ripe in containers or a seed bed in a position in light shade.
When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. If you have sufficient seed, it might be worthwhile trying an outdoor sowing in a seed bed in early spring. Grow the plants on in the seedbed for their first year and plant them out the following spring. Division in March or October. Use a sharp spade or knife to divide the rootstock, making sure that each section has at least one growth bud. Very easy, larger divisions can be planted out direct into their permanent positions. It is better to pot up the smaller divisions and grow them on in light shade in a cold frame until they are well established before planting them out in late spring or early summer.
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Photographs by Dick Culbert, Lisa Cyr