Othonna TRIPLINERVIA

Othonna TRIPLINERVIA - Three-nerved othonna, Othonna triplinervia.

Can be grown in bonsai style!

Othonna is a genus in the aster family (Asteraceae), comprising about 85 accepted species distributed predominantly in southern Africa, from Angola and Namibia to the Cape Provinces, Lesotho, Eswatini, KwaZulu-Natal, Free State, Northern Provinces, and Zimbabwe. Members of the genus occur in dry shrublands, on sandy and rocky slopes, in rock crevices, on plains, and in seasonally arid subtropical habitats.

The genus is characterized by tuberous or thickened underground organs, sometimes a pronounced caudex, as well as succulent or semi-succulent shoots. Growth forms vary from small tuberous herbs to subshrubs and dwarf shrubs. Leaves in different species can be entire, lobed, or dissected, sessile or petiolate, often fleshy, adapted to seasonal moisture deficits.

Inflorescences in othonnas are flowerheads (capitula), most often yellow, solitary or clustered in small groups. The fruits are single-seeded cypselae (achenes), usually very light, equipped with a pappus of bristles by means of which they are dispersed by the wind. Many species are characterized by seasonal growth, in which leaves develop during the cooler and wetter period of the year.

Three-nerved othonna is a succulent shrub with a brittle stem up to 1.5 m (5 ft) tall. Leaves are crowded at the branch ends, obovate, barely lobed. Flowerheads are radiate, numerous in terminal corymbs on long peduncles, yellow.

Seeds are small, enclosed in light single-seeded fruits equipped with a white pappus of bristles. Before sowing, the cypselae are cleaned of inflorescence remnants. Scarification and stratification are usually not required. To prevent fungal infections, short-term soaking can be carried out first in warm water at 50-60 °C (122-140 °F) for a few minutes, then in a 1% solution of potassium permanganate for 1-2 hours. Additionally, the use of stimulants such as SUPERthrive, HB-101, Aminozol, Epin, or Zircon is permitted.

Sowing is preferably carried out in autumn, which corresponds to the natural cycle of the species, although under controlled conditions it is possible at other times of the year. A breathable and permeable substrate based on coarse sand, fine perlite, and a small organic component is used. Seeds are laid out on the surface or covered with a very thin layer of sifted sand. Moistening is performed with a spray bottle. The container is kept in a mini-greenhouse or under film at a temperature of about 15-22 °C (59-72 °F), in bright indirect light, with daily airing. Waterlogging and complete drying out of sowings are impermissible.

The first sprouts usually appear in about 10-14 days. The most typical germination period is 2-3 weeks. The maximum germination period can reach 4-6 weeks. After seedlings appear, the cover is removed gradually, illumination is increased, and watering is transitioned to a very careful regime. Pricking out is performed after several true leaves have formed, when the seedlings are strong enough to withstand transplanting without damaging the young tuberous base.

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For most cultivated othonna species, the brightest possible illumination is used. The best placement is south-, southeast-, or southwest-facing windows, where several hours of direct sun are provided. With insufficient light, shoots stretch out, internodes lengthen, and flowering weakens. Supplementary lighting can be used during the overcast season.

During the active growth period, which in tuberous South African species usually falls in autumn, winter, and spring, a cool-temperate regime of around 12-22 °C (54-72 °F) is maintained. Summer dormancy is preferably spent at 20-28 °C (68-82 °F) in dry and well-ventilated conditions. A short-term drop in temperature is possible only under nearly dry conditions, while sustained chilling below 5 °C (41 °F) is undesirable, especially in damp substrate.

Watering is carried out moderately during the active growth period, after the upper layer of soil dries out. Water used is soft or settled, without waterlogging the root zone. Excess water from the tray is always drained. In summer, when the plant enters semi-dormancy, watering is sharply reduced and a nearly dry regime is maintained. Overwatering quickly leads to rotting of the tuber and shoot bases, while prolonged complete drying out during the active season slows growth and bud setting. Spraying is usually not required, but dust is gently wiped from the leaves.

For planting, a very loose mineral-organic substrate with a high content of perlite, coarse sand, and fine drainage material is used. Shallow pots with mandatory drainage holes are suitable. Repotting is carried out as the volume is filled, usually once every 2-3 years, before active growth begins. The plant is fertilized rarely, once every 3-4 weeks during the growing season, with a weak solution of fertilizer for succulents. Hard pruning is usually not required; only dry or weakened shoots are removed.

Propagation by cuttings is not always possible for the genus and is used limitedly in tuberous forms; therefore, seed sowing remains the primary method for renewing a collection. In species with elongated shoots, rooting is possible only in very light mineral soil and under strict moisture control.