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Origin and Habitat: Central and lateral drainage area of the Sundays River, western part of the Eastern Cape Province, South-Africa. It can be found as far south as the vicinity of Port Elizabeth and westwards as far as Paardepoort near the border between the Western & Eastern Cape provinces. Possibly differentiated into two varieties H. glauca var. glauca in the Zuurberg mountains in the east, and H. glauca var. herrei in the Kleinwinterberg and Groot Heights in the west.
Habitat and ecology: Within this range, Haworthia glauca typically grows in very well-drained sandy soil, either in direct sunlight, or under bushes which serve as partial protection from the sun or in crevices on sheer rock faces.
- Haworthia glauca Baker
Haworthia glauca Baker
J. Linn. Soc., Bot. 18: 203 1880.
- Haworthia glauca Baker
- Catevala glauca (Baker) Kuntze
- Haworthia reinwardtii subs. glauca (Baker) Halda
- Haworthia reinwardtii var. glauca (Baker) Halda
- Haworthiopsis glauca (Baker) G.D.Rowley
- Haworthia carrissoi Resende
Haworthia glauca var. herrei (Poelln.) M.B.Bayer
Haworthia Handb. 122 1976.
- Haworthia glauca var. herrei (Poelln.) M.B.Bayer
- Haworthia reinwardtii var. herrei (Poelln.) Halda
- Haworthiopsis glauca var. herrei (Poelln.) G.D.Rowley
- Haworthia eilyae Poelln.
- Haworthia eilyae var. zantneriana Resende
- Haworthia glauca f. armstrongii (Poelln.) M.B.Bayer
- Haworthia armstrongii Poelln.
- Haworthia glauca f. jacobseniana (Poelln.) Pilbeam
- Haworthia jacobseniana Poelln.
- Haworthia glauca f. jonesiae (Poelln.) Pilbeam
- Haworthia herrei var. depauperata Poelln.
- Haworthia herrei var. poellnitzii Resende
Description: Haworthia glauca typically has harder, pointed, succulent leaves which terminate in a sharp point, these are packed densely along its stems. The stems branch from the base, and the plant can form clumps. The leaves vary through the seasons, being green or light blue ("glauca" = "blue") when the plant is growing and assuming a purplish cast during the resting period.
Stems: Elongate. The stems branch from the base, and the plant can form clumps.
Rosettes: 2 to 8 cm cm in diameter.
Leaves: Numerous, oblong-lanceolate to 6 x 1.5 cm, erectly spreading or incurved, scabrid, with 5 to 7 lines on the back glaucous grey-green, surfaces without tubercles or with slight tubercles.
Inflorescence: Simple or occasionally compound, to 30 cm long.
Flowers: Tube obcapitate, curved; Tepals revolute.
Chromosome number: This species has 29 chromosomes in its somatic cells:16 large and 12 small chromosomes which proves that the species is tetraploid. Haworthia glauca is undoubtedly a hypertetraploid and apparently is the first recorded species of Haworthia with an extra chromosome.
Taxonomy note: The leaves may be incurved, vertical and erect, or spreading. In some varieties, the leaves have slight tubercles. However colour, leaf tuberculation, plant growth characteristics, leaf-shape, -size and -presentation are all so variable through the range of this species and within each population, that recognition of specific forms as varieties is impractical. In summation the various elements collected and recorded belong to a single species complex. There is no suggestion of geographic variability to suggest infra-specific grouping although it is admitted that for the area east of the Sundays River, evidence is sparse. In conclusion it is suggested that H. glauca be retained as the species found in the central and lateral drainage area of the Sundays River, possibly differentiated into two varieties H. glauca var. glauca in the Zuurberg mountains in the east, and H. glauca var. herrei in the Kleinwinterberg and Groot Heights in the west. Allied to Haworthia coarctata this species forms part of the subgenus Hexangulares. Recent phylogenetic studies have demonstrated that subgenus Hexangulares is actually relatively unrelated to other Haworthias (being more closely related to Gasterias. It will therefore comprise a new, separate genus, Haworthiopsis, and this species will accordingly become "Haworthiopsis glauca".
Subspecies, varieties, forms and cultivars of plants belonging to the Haworthia glauca group
- Haworthia glauca Baker: has thin creeping or upright stems packed with glaucous, bluish-green triangular leaves, growing in clumps. Distribution: Zuurberg mountains, Eastern Cape Province, South-Africa.
- Haworthia glauca var. herrei (Poelln.) M.B.Bayer: Leaves lanceolate, spreading, with tubercles. Distribution: Kleinwinterberg and Groot Heights, Eastern Cape Province, South Africa.
- Haworthia glauca f. jonesiae (Poelln.) Pilbeam: has pencil-thin stems.
Bibliography: Major references and further lectures
1) Bill Keen “CACTI AND SUCCULENTS: Step-by-Step to Growing Success” Crowood, 18 October 2011
2) Urs Eggli “Illustrated Handbook of Succulent Plants: Monocotyledons” Springer, 2001
3) Charles L. Scott “The genus Haworthia (Liliaceae): a taxonomic revision” Aloe Books, 1985
4) Stuart Max Walters “The European Garden Flora: Pteridophyta, Gymbospermae, Angiospermae-Monocotyledons” Cambridge University Press, 1984
5) M. B. Bayer “The new Haworthia handbook” National Botanic Gardens of South Africa, 1982
6) John Pilbeam “Haworthia and Astroloba: A Collector's Guide” B. T. Batsford Limited, 1983
7) M. B. Bayer “Variation in Haworthia with particular reference to HAWORTHIA GLAUCA, Baker” Haworthia Study Group, New South Wales – October 1970 (Posted on June 24, 1970) <http://haworthiaupdates.org/variation-in-haworthia-with-particular-reference-to-haworthia-glauca-baker/>
8) Richard Goldschmidt “Portugaliae Acta Biologica: Morfologia, fisiologia, genética e biologia geral” , Volumi 1-2 Instituto Botânico de Lisboa, 1944
9) The journal of heredity, Volume 53 1962
Haworthia glauca Photo by: Valentino Vallicelli
Haworthia glauca Photo by: Valentino Vallicelli
Cultivation and Propagation: Haworthia glauca is a proliferous species of easy cultivation and relatively low maintenance, forming clumps in nature. Its interest lies in its ability to change colour: in cooler weather the plant blush bronze-red. It is also a good houseplant, and can be an excellent subject for the beginning succulentophile (they can grow easily on window sills, verandas and in miniature succulent gardens where they are happy to share their habitat with other smaller succulent plants, or in outdoor rockeries). It is a winter grower and is dormant in the hottest summer months. In cultivation it needs more sunny position to show its beauty.
Growth rate: Haworthia glauca are relatively slow-growing plants that offsets freely to form small clusters whit time.
Soil: They are tolerant of a wide range of soils and habitats, but prefer a very porous potting mix to increase drainage. A non-acid soil is ideal. You can grow a plant in a 10-15 cm pot for years and have perfectly happy plants. For best results, use a shallow pot.
Exposition: The plant needs little bit more exposed situation to let plants grow compactly. With some sun exposure the leaf develops a nice reddish tint and remains compact.
Watering: During the hot summer months, the soil should be kept moist but not overly wet. During the winter months, water only when the soil becomes completely dry. Wet soil quickly causes root and stem rot, especially during chilly winter months. No water should ever be allowed to stand around the roots. Low ambient humidity is always needed.
Fertilization: The plants are fertilized only once during the growing season with a balanced fertilizer diluted to ½ the recommended strength.
Hardiness: Although the plant will survive mild frost if kept dry (hardy as low as -5° C) it should be protected from severe cold and prolonged frost conditions.
Rot: Rot is only a minor problem with Haworthia if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much. Care must be given in watering, keeping them warm and wet while growing, and cooler and dry when dormant.
Remarks: Haworthias are best planted in a shaded and airy part of the greenhouse, and not too close to the glass roof or sides of the house as the plants can overheat during hot spells.
Propagation: Haworthia are easily propagated by the removal of offshoots in spring or summer. They can also be grown from seed.
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