Crassula obovata var. dregeana
Introduction
A succulent plant growing in crevices or in rocky grassland patches. It has small whitish flowers and fleshy leaves with peculiar hairs, giving it a soft grey appearance. This species will easily grow in shady areas, unlike most of the other species of Crassula.
Description
Description
Crassula obovata var. dregeana is a decumbent-erect succulent, up to 300 mm long. The base of the plant is often woody, and the leaves fleshy and densely covered with adpressed and recurved hairs. Basal leaves are arranged in rosettes and are obovate to spathulate, with the lower surface convex and the upper surface usually flat. Upper leaves are arranged in opposite pairs and are obovate to elliptic, with the lower surface convex and the upper surface concave. The upper leaves are usually (3–)4–5 mm thick, unlike var. obovata which has thinner leaves.
The inflorescences are flat-topped cymes usually with 4–8(–10), tubular flowers that have white or cream-coloured (rarely pink) petals. The petals are 5–7 mm long. The flowering period of C. obovata var. dregeana is in autumn (from April to June).
Conservation Status
Status
Crassula obovata var. dregeana is considered to be Vulnerable (VU) according to the Red List of South African plants, because of its small distribution range and threats posed by grazing and frequent fires.
Distribution and habitat
Distribution description
The genus Crassula has over 300 species, of which 150 are centered in South Africa. The species are distributed in Africa, Europe, America, New Zealand and the southern islands and the distribution is concentrated in semi-arid and winter-rainfall areas on rocky outcrops, in grassland or forest.
The distribution range of C. obovata var. dregeana is limited to the southern area of the KwaZulu-Natal Province crossing over into the Eastern Cape Province. It typically grows in rock crevices or in rocky grassland outcrops on Table Mountain Sandstone, at 300–500 m above sea level.
Derivation of name and historical aspects
History
Crassula is a diminutive form of the Latin term crassus, meaning ‘thick’, which points to the succulent leaves typical of the genus. The species name obovata refers to the egg-shaped leaves. The variety name dregeana, honours the scientist and well-known plant collector Johann Franz Drège who collected the type material. Drège travelled to South Africa in the 19th century, collected many plant specimens (more than 9 500) and published his collecting notes in a book called Zwei Pflanzengeographische Documente, in 1843.
Ecology
Ecology
The genus possesses a Crassulacean Acid Metabolism (CAM) often found in succulent plants. This metabolic pathway helps plants to retain water, by closing their stomata during the day and opening them only at night. It also improves absorption of carbon dioxide for effective photosynthesis. CAM allows plants to survive in harsh environments where water is not readily available.
Uses
Use
There are no records of medicinal uses for C. obovata var. dregeana.
Growing Crassula obovata var. dregeana
Grow
Crassula obovata var. dregeana is very easy to grow. It requires well-drained soil, little water and sunny or shady conditions. It can be watered 3 times a week during the summer season and twice during the winter season. This variety makes an excellent candidate for a water-wise garden.
Plants can be propagated through leaf or stem cuttings (specifically tips before flowering) or seed. Well-drained soil is required for cuttings to root or seeds to germinate. Mix 70% sterilised sandy soil with 30% of potting soil in a container. Water regularly initially until roots have formed and seeds have grown to small seedlings and harden off by watering less frequently. Place it in a cool area or a glasshouse in partial shade where it gets morning or afternoon sunlight. The seedlings can be planted out as soon as it has formed clustered leaves.
References
- Glen, H. 2004. Sappi what’s in a name?. Jacana Media (PTY) Ltd. Johannesburg. 13, 53, 68.
- Gordon, R. 2003. Crassula: a grower’s guide. Cactus & Co, libri, Italy.
- iSpot southern Africa. https://www.ispotnature.org/communities/southern-africa/view/observation/348283/crassula-obovata-var-dregeana. Accessed on 17 August 2017.
- Leistner, O.A. (ed.). 2000. Seed plants of southern Africa: families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
- Notten, A. 2010-02. Crassula rubricaulis Eckl. & Zeyh. (Crassulaceae). PlantZAfrica. Internet 1 pp. http://pza.sanbi.org/crassula-rubricaulis. Accessed on 17 August 2017.
- The Plant List. 2017. http://www.theplantlist.org Accessed on 4 August 2017.
- Toelken, H.R. 1975. New taxa and new combinations in the genus Crassula. Journal of South African Botany 41(2): 93–124.
- Toelken, H.R. 1985. Crassulaceae. Flora of Southern Africa 14: 1–229.
- Victor, J.E. 2007. Crassula obovata Haw. var. dregeana (Harv.) Toelken. National Assessment: Red List of South African Plants version 2017.1. Accessed on 7 August 2017.
Credits
Kagiso Sharlene Mashego and Marianne le Roux
Pretoria National Botanical Garden
January 2018
Plant Attributes:
Plant Type: Succulent
SA Distribution: Eastern Cape, KwaZulu-Natal
Soil type: Sandy, Loam
Flowering season: Autumn, Winter
PH: Acid
Flower colour: White, Cream
Aspect: Full Sun, Shade, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Easy
Special Features:
Drought resistant
Good potplant
Indoor plant
Horticultural zones
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