Oriental Bittersweet - Celastrus

Oriental bittersweet is the most valuable climbing plant with ornamental fruit. It is generally hardy, undemanding and vigorous in habit, which makes him well worth of any gardener's interest.

Celastrus orbiculatus (ph. Sz. Marczyński)

Szczepan Marczyński

Celastrus is a member of the Celastraceae family. There are around 30 species belonging to this genus, native mostly to subtropical regions.

A few of them are capable of enduring polish climatic conditions, but only Celastrus orbiculatus - Oriental bittersweet is universally cultivated. In some collections you can also encounter a similar species from this family, Celastrus scandens - American bittersweet. Both species have vigorous twining stems and are dioecious. They bear inconspicuous, white to greenish flowers, gathered in clusters.

Fruits appear only on female plants pollinated by neighboring male specimens. Rounded yellow three-valved capsules split open at maturity to reveal closely packed seeds completely enclosed in a fleshy red or orange arils. Upon ripening the yellow outer covering contrasts beautifully with the red or pink inside. The fruits stay decorative for several months and make an excellent addition to dried flower arrangements or interior decoration.

Celastrus orbiculats - Oriental Bittersweet is native to Japan, China, and Korea. It grows very vigorously attaining a height of 12 m. Its stems are covered with numerous small axillary buds with spine-like outer scales. Leaves are rounded or elliptic, finely toothed and in autumn they turn bright yellow. Flowers emerge from leaf axils.

Celastrus orbiculatus (ph. Sz. Marczyński)

Two varieties are encountered in cultivation:

• 'Diana' - a profusely fruiting female clone (it sets fruits only if there's a make clone in the neighborhood that can pollinate its flowers).
  
  
• 'Hercules' - a male clone, a good pollinator for female plants, also for 'Diana'.
  
  

Celastrus scandens - American Bittersweet is native to Northern America. It's less rampant than Oriental Bittersweet - it attains a height of about 7 m. It's not popular in Poland, as it rarely sets fruit in our cool climate. Flowers appear in terminal panicles, which distinguishes it from C. orbiculatus.

Requirements. It can grow in all types of soil, including drying soil. It's better to plant it in poor soil, as in the fertile one it can become too expansive. Well adaptable to different levels of pH of the soil. Tolerates half shade, but grows best and yields best fruit in full sun. It's frost hardy and only rarely attacked by pests and diseases. Responds well to pruning.

Celastrus orbiculatus over the entrance to the bloc in Warsaw's Ursynów, Poland(ph. Sz. Marczyński)

Use.It is perfectly suited for covering tall fences, solid structures (arbors, pergolas, arches, unsightly buildings etc.), and makes a good plant for creating acoustic screens near the roads and motorways. It also looks interesting climbing into old tree trunks or large trees. Due to its rampant growth, however, it shouldn't grow next to bushes, small trees or conifers as it may choke them up. If grown in a proper place and kept in check by pruning, it will adorn your garden without posing any threat to other plants.

You should only buy vegetatively propagated plants from a reliable source, as only such plants will grow best and yield fruit. Avoid purchasing seed-propagated plants of unknown sex, so frequently encountered in commerce.

Celastrus orbiculatus in the gardens of the Library of Warsaw University , Poland (ph. Sz. Marczyński)

Celastrus orbiculatus 'Hercules'(ph. Sz. Marczyński)

Celastrus orbiculatus in the gardens of the Library of Warsaw University, Poland (ph. Sz. Marczyński)

Celastrus orbiculatus in the gardens of the Library of Warsaw University, Poland (ph. Sz. Marczyński)

Celastrus orbiculatus on the fence (ph. Sz. Marczyński)

Celastrus orbiculatus on he building of the Warsaw Agricultural University, Poland (ph. Sz. Marczyński)