Othonna CLAVIFOLIA

Othonna CLAVIFOLIA - Club-leaved othonna, Othonna clavifolia, Crassothonna.

Othonna is a genus in the Aster family (Asteraceae), comprising about 85 recognized species distributed mainly in southern Africa, from Angola and Namibia to the Cape Provinces, Lesotho, Eswatini, KwaZulu-Natal, Free State, Northern Provinces, and Zimbabwe. Representatives of the genus are found in dry shrublands, on sandy and rocky slopes, in rock crevices, on plains, and in seasonally dry 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. In different species, leaves can be entire, lobed, or dissected, sessile or petiolate, often fleshy, adapted to seasonal moisture deficits.

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

Club-leaved othonna is a rare fleshy plant having a gray caudex up to 5 cm (2 in) high and stems up to 10 cm (3.9 in) high. The leaves are cylindrical-clavate, succulent, green. Flower heads are discoid, solitary, 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 infestations, 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% potassium permanganate solution for 1-2 hours. In addition, the use of stimulants is permissible, for example SUPERthrive, HB-101, Aminosol, Epin, or Zircon.

Sowing is preferably carried out in autumn, which corresponds to the natural cycle of the species, although under controlled conditions it is also possible at other times of the year. An air- and water-permeable substrate based on coarse sand, fine perlite, and a small amount of organic matter is used. Seeds are laid out on the surface or sprinkled with a very thin layer of sifted sand. Moistening is performed from a spray bottle. The container is kept in a greenhouse or under film at a temperature around 15-22 °C (59-72 °F) in bright diffused light, with daily ventilation. Overwatering and complete drying out of sowings are unacceptable.

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 sprouts appear, the covering is removed gradually, illumination is increased, and watering is shifted to a very gentle mode. Pricking out is performed after the formation of several true leaves, when the seedlings have strengthened sufficiently and can tolerate transplanting without damage to the young tuberous base.

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For most cultivated othonna species, the brightest possible lighting is used. The best placement is on southern, southeastern, or southwestern windows where several hours of direct sun are provided. With a lack of light, shoots stretch out, internodes elongate, and flowering weakens. Supplemental 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-moderate regime around 12-22 °C (54-72 °F) is maintained. Summer dormancy is best spent at 20-28 °C (68-82 °F) in dry and well-ventilated conditions. A short-term drop in temperature is possible only with nearly dry maintenance, and persistent cooling below 5 °C (41 °F) is undesirable, especially in a damp substrate.

Watering is carried out moderately during the active growth period, after the upper part of the soil dries out. Soft or settled water is used, without overmoistening the root zone. Excess water from the drip tray is obligatorily drained. In summer, when the plant enters semi-dormancy, watering is sharply curtailed and a nearly dry regime is maintained. With overwatering, rots of the tuber and base of shoots develop quickly, while prolonged complete overdrying in the active season inhibits growth and bud setting. Misting is usually not required, but dust is gently removed from the leaves.

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

Cuttings are not always possible for the genus and have limited application in tuberous forms, so sowing seeds more often remains the primary method of updating a collection. In species with elongated shoots, rooting is possible only in very light mineral soil and under strict humidity control.