Othonna (2015)

By Eric Driskill (January 2015)

Othonna is a genus in the Composite family. The genus boasts over 100 species, which grow in the winter rainfall areas of Southern Africa, Northern and Western Cape and the southwestern section of Namibia. Not all Othonna species are succulent, but the geophytes or dwarf caudiciforms are found in the western Cape and Namaqualand.

This family is known for having a flower head that appears to be one flower, but is a cluster of many small florets armed with colorful bracts. A flower with tightly packed flowers in a headlike inflorescence is known as a capitulum. Flowers are bright yellow, with a few species having purple flowers. Seeds are held in loose clusters and dispersed by the wind.

Othonnas are typically hardy and easy to grow, although like many plants, one grower may find them hassle-free, while another grower finds them particularly challenging. The plants should be watered generously during their strict winter growing season, which typically runs from early fall through late spring. Othonnas can also benefit from a daily misting through their growing season.

During this growing season, the plants should be moved into strong direct sunlight to achieve compact growth. The warmer months send many othonnas into dormancy, which is indicated by their dropping leaves. Plants should then be moved from strong light to a shadier, cooler area of the greenhouse.

Watering should be greatly reduced. Some growers ignore them completely with the watering can during the summer dormancy. I don’t allow them to become bone dry, or certainly not for very long, before giving them a light watering.

Many of the succulent othonnas are appealing even at a young age, but often it’s when someone sees an older specimen plant that these plants are either added to the wish list or moved toward the top. One of the more striking species is O. herrei, which looks like something prehistoric. This species is a thick and rather knobby-stemmed miniature shrub up to about 8 inches tall, with bluish leaves.

An older specimen of O. retrofracta is truly a sight to behold. These plants develop a small caudex with dark red, peeling bark. In addition, their small leaves help perfectly qualify this plant as a bonsai subject. Pictured below is a rather young plant that I am attempting to shape.

Another stunning species is O. cacalioides, which develops a small caudex with very short branches and chalky, blue-colored leaves. O. euphorbioides, which develops into a shrub up to a foot tall, has attractive peeling, yellowish-red bark and arms with remains of inflorescences persisting.

O. quercifolia also develops a small, spherical caudex and dark-green leaves. The plant pictured below is either O. quercifolia (if it develops peeling bark) or a hybrid between O. quercifolia and O. retrofracta (if no peeling bark appears).