Astroloba rubriflora (L.Bolus) Gideon F.Sm. & J.C.Manning

<i>Astroloba rubriflora</i> Fig 1 Al Laius
<i>Astroloba rubriflora</i> Fig 2 Al Laius

This plant was described as Poellnitzia rubriflora in 1940 and was then sunk into Astroloba in 2000.

Astroloba derives from the Greek word, astros, which means, ‘star’ and lobos, which means, ‘lobe’, referring to the star-shaped petals of the flower. The species name rubriflora means ‘red flowers’ and refers to the red colour of the flowers. A. rubriflora was previously known as Poellnitzia rubriflora, in a genus on its own, because of the unusual shape and colour of the flowers. The genus Astroloba closely resembles some species of Haworthia, but differs in that they do not have the 2-lipped opening of the flowers.

This species is a succulent perennial, with sprawling stems that can grow up to 240mm tall. Younger plants have erect stems that increase in size as the plant grows older. The light green, waxy leaves are smooth, spirally arranged, with very sharp tips. Leaves on the lower part of the plant can turn brown with severe sun exposure.

<i>Astroloba rubriflora</i> Fig 3 Al Laius

The slender inflorescence of A. rubriflora can grow up to 500mm long, and consists of red, tubular-shaped flowers, with green tips. The tubular flowers have a narrow opening with flaps that regulate access to the nectar. The flowers bloom in summer, and are arranged in an upright position. Seed capsules are trilocular and contain brown to black winged seeds. A. rubriflora is the only plant in the genus that has red flowers. The tubular flowers face upwards, and are adapted to attract sunbirds for pollination.

A. rubriflora occurs in the Robertson Karoo, in the Western Cape. The distribution range is between Robertson, Bonnievale and McGregor. This is a winter rainfall region with very high temperatures during the summer months. This species typically grows in nutrient-poor soils, underneath shrubs, on lower karroid hills and rocky slopes.

According to the Red List of South African plants, this species has a conservation status of Vulnerable (VU), caused by habitat loss because of the expansion of vineyards and fruit farms.

Astroloba rubriflora can be propagated from seed and cuttings. Sow seed in autumn, and fresh seed is always the best to use. Sow in a well-drained medium about 2mm deep. Do not sow seeds too deep or too close to each other as they can rot, because of fungal infection. Spray regularly with a fungicide until the seedlings are 2–3cm tall and ready to be transplanted.

Take cuttings during the active growing period (spring or summer). Take cuttings just below the internode and insert in a mixture of 60% sharp sand and 40% sieved compost. A rooting hormone can be used for optimum results. Water the cuttings, using a fine mist sprayer. Always use sterilised equipment and soil medium. Rooted cuttings need to be transplanted into a soil medium with a higher compost ratio. Finally place transplanted plants in a partially shaded area.

Text and photos: Al Laius

No part of this article may be reproduced without permission. Copyright BCSS & the Author 2023

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