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Origin and Habitat: Little Namaqualand, Cape Province, South Africa. Adromischus roaneanusSN|26236]]SN|26236]] is locally common between Brandkop, Vanrhynsdorp and Clanwilliam but also occasionally on the eastern slopes of the Cedarberge and the Swart Ruggens range.
Type locality: Vanrhyn's Pass.
Habitat: It is usually restricted to exposed positions, but also in the shade of other plants amongst quartz rocks and sandstone outcrops with loose reddish wind-blown sand. The area is very rich in succulent plants, some of which are endemic to the region. They include Thumb grass (Dregeochloa pumila), Aloe krapohlianaSN|637]]SN|637]] var. dumoulinii, Crassula brevifolia, Euphorbia ephedroides, Cotyledon orbiculataSN|492]]SN|492]], Euphorbia hamata, Pelargonium carnosum, Othonna clavifolia, Pelargonium echinatum, Cheiridopsis verrucosaSN|18801]]SN|26035]], Cheiridopsis browniiSN|26035]]SN|18801]], Conophytum saxetanumSN|22686]]SN|22686]] and Tridentea herrei. Non-succulent plants include Dianthus namaensis and Rhyssolobium dumosum. Lichens are also very prominent on rocks and on plants.
Synonyms:
- Adromischus roaneanus Uitewaal
Adromischus roaneanus Uitewaal
Natl. Cact. Succ. J. 7: 69 1952
Synonymy: 3
- Adromischus roaneanus Uitewaal
- Adromischus grasbergensis Hutchison
- Adromischus violaceus Hutchison
Description: Adromischus roaneanusSN|27260]]SN|26236]] also spelled "roanianus" is an odd-looking succulent plant with stem of young plants almost erect becoming prostrate with time. It is one the most variable species in the genus especially regarding the leaf shape and comprises many morphological and geographical variants, every clone is distinct and individuals may be very different one to each other even within the same population. Some forms are so different that no identifying feature helps to relate them to each other. Cultivated plants can be reliably distinguished only when seeds or details of wild source are available.
Note: Plants found in South Africa very rarely match the widely-cultivated type material, and in habitat are often found plants with a horny margin around the leaf, but zig-zagging stems with long internodes appear to be very rare. The variable Adromischus hemisphaericusSN|26236]]SN|27260]] grows throughout the Bokkeveldberge and the two may be the same.
Habit: Perennials leaf-succulent plant with erect to decumbent slender branches up to 25 cm long, little branched and often zig-zagging, with fibrous roots.
Leaves: Up to 3 cm long, very variable in shape, oblanceolate, rarely obovate or linear-oblanceolate, more or less strongly cuneate, acute, obtuse or cuspidate, dorsientrally flattened with horny margin usually restricted to the upper half, grey-green to grey with a thick bloom and rarely with small purple spots.
Inflorescence: Spike-like thyrse with 1-flowered cyme, 20-35 cm high, grey-green to grey.
Flowers Buds straight, narrowing towards apex. Flowers 1-1,2 cm long, with 5 petals basally fused to form a greyish-white cylindrical tube gradually tapered towards tip, erect at first, later spreading. Corolla green with purplish lobes. Pedicels 2--4 mm long. Calyx 1,5-2 mm long, grey. Corolla with cylindrical tube 11-14 mm long, pale green. Lobes broadly triangular, 2-3 mm long, cuspidate, rough and hairless, white to cream often tinged pink and with mauve mucro. Anthers protruding. Squamae square to transversely oblong, 0,7-1,2 X 0,9-1,2 mm, slightly emarginate, usually somewhat broader at about the middle.
Blooming season: Spring to early summer (November, December).
Bibliography: Major references and further lectures
1) Hermann Jacobsen “A handbook of succulent plants: descriptions, synonyms, and cultural details for succulents other than Cactaceae” Volume 1 Blandford Press, 1960
2) Urs Eggli “Illustrated Handbook of Succulent Plants: Crassulaceae” Springer for Science, 01/gen/2003
3) Werner Rauh “Die großartige Welt der Sukkulenten : Anzucht und Kultur sukkulenter Pflanzen mit Ausnahme der Kakteen” Hamburg ; Berlin : P. Parey, cop. 1967
4) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/ago/2011
5) J.P. Roux “Flora of South Africa“ 2003
6) Domitilla Raimondo “Red list of South African plants 2009” South African National Biodiversity Institute, 2009
7) Ernst Van Jaarsveld, Ben-Erik Van Wyk, Gideon Smith “Succulents of South Africa: A Guide to the Regional Diversity” Tafelberg Publishers, Limited, 01/lug/2000
8) Ben P. Barkhuizen “Succulents of Southern Africa: With Specific Reference to the Succulent Families Found in the Republic of South Africa and South West Africa” Purnell, 1978
9) D. J. Court “Succulent Flora of Southern Africa” A.A. Balkema, 1981
10) G.E. Gibbs Russsell, L. Watson, M. Koekemoer, L. Smook, N.P. Barker, H.M. Anderson,M.J. Dallwitz (ed. O.A. Leistner). “Grasses of southern Africa” National Botanical Gardens, Botanical Research Institute, South Africa. 1990.
11) Fish, L. Poaceae Barnhart (Grass family) in G.F. Smith et al. (eds), "List of Southern African succulent plants." National Botanical Institute/Succulent Society of South Africa, Umdaus Press, Pretoria. 1997
12) Gunn, M. & Codd, L.E. "Botanical exploration of southern Africa." A.A. Balkema, Cape Town for the Botanical Research Institute. 1981
13) Mabberley, D.J. "The plant book." Cambridge University Press, Cambridge. 1997
14) Mucina, L. & Rutherford, M.C. (eds). "The vegetation of South Africa, Lesotho and Swaziland." Strelitzia 19. South African National Biodiversity Institute, Pretoria. 2006
15) Adromischus roaneanus Uitew. in Natn. Cactus Succul. J. 7: 69, figs 1952
16) Adromischus roaneanus Tolken in Bothalia 12: 385 1978.
Cultivation and Propagation: Adromischus roaneanusSN|26236]]SN|26236]] is a most beautiful succulent but rarely seen in cultivation. It is not the easiest species to cultivate, and highly prone to rotting off, both at the height of winter or summer.
Growth rate: It is a relatively fast growing species.
Soil: Use mineral well-permeable substratum with very little organic matter (peat, humus). It needs perfect drainage to flourish.
Repotting: Repotting every 2-3 years. As it is especially prone to rot under-pot in a smaller container filled with very porous compost. Use pot with good drainage. All species of this genus are happy in small pots.
Exposure: It grows best in a partially shaded position. It got sunburned if exposed to midday sun. I would not advise that any Adromischus be grown in shade, as they soon become atypical in this condition.
Hardiness: Require a minimum temperature 5°C (But hardy down to -7°C for short periods), with good drainage and dryness in winter to resist the cold.
Watering: It takes more water than cacti, but let the soil dry between soaking, in the wild, it receives rain mostly in spring and fall. Must have very dry atmosphere. Water less in winter but do not allow it to shrivel.
Pest & disease: It is vulnerable to mealybugs and rarely scale. It is prone to rotting from the tuberous base or from dried inflorescences. If the plants are not watered and “aired” correctly, fungicides won't help all that much.
Maintenance: As the plant matures, the centre becomes bare. When it does, restart it from side cuttings and throw away the central part. Remove flower spikes before winter.
Propagation: Usually propagate from single leaves (leaf cuttings) or stem cuttings seed propagation is rarely used. Leaves easily root and produce new plants. Twist off a leaf and permit it to dry out a couple of days, lay it on the soil and insert the stem end partially into the soil. The original leaf should not be removed until it has dried up. Try to keep the leaf somewhat upright so that the roots are able to grow downward. If grown in a container, bottom watering by immersing the container is recommended.
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