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Origin and Habitat: Eastern Cape, South Africa. It is concentrated in the Grahamstown area but extending to Addo in the west and near the Fish River in the east.
Habitat: It grows usually on rocky terrain, rather than on open grass-lands. It forms dense clusters and often grows in full exposed situations and, possibly because of vegetative reproduction, populations tend to be very uniform. In the eastern part of the range blends with Haworthia fasciata. In the area of Grahamstown / Port Alfred / Great Fish River its distribution range meets with Haworthia reinwardtii.
- Haworthia coarctata Haw.
Haworthia coarctata Haw.
Philos. Mag. Ann. Chem. 66: 301 1824.
- Haworthia coarctata Haw.
- Aloe coarctata (Haw.) Schult. & Schult.f.
- Apicra bicarinata Resende non Haw.
- Catevala coarctata (Haw.) Kuntze
- Haworthia coarctata var. coarctata (Haw.)
- Haworthia reinwardtii subs. coarctata (Haw.) Halda
- Haworthia reinwardtii var. coarctata (Haw.) Halda
- Haworthiopsis coarctata (Haw.) G.D.Rowley
- Haworthia baccata G.G.Sm.
- Haworthia coarctata f. chalwinii (Marloth & A.Berger) Pilbeam
- Haworthia chalwinii Marloth & A.Berger
- Haworthia reinwardtii var. chalwinii (Marloth & A.Berger) Resende
- Haworthia reinwardtii var. conspicua Poelln.
- Haworthia coarctata f. conspicua (Poelln.) Pilbeam
- Haworthia coarctata var. haworthii Resende
- Haworthia coarctata var. kraussii Resende
- Haworthia coarctata f. major Resende
- Haworthia coarctata f. pseudocoarctata Resende
- Haworthia coarctatoides Resende & Viveiros
- Haworthia fallax Poelln.
- Haworthia reinwardtii var. fallax (Poelln.) Poelln.
- Haworthia fulva G.G.Sm.
- Haworthia greenii var. silvicola G.G.Sm.
- Haworthia musculina G.G.Sm.
- Haworthia reinwardtii var. committeesensis G.G.Sm.
- Haworthia reinwardtii var. huntsdriftensis G.G.Sm.
- Haworthia resendeana Poelln.
Haworthia coarctata var. adelaidensis (Poelln.) M.B.Bayer
Haworthia Revisited 172 1999.
- Haworthia coarctata var. adelaidensis (Poelln.) M.B.Bayer
- Haworthia coarctata subs. adelaidensis (Poelln.) M.B.Bayer
- Haworthia reinwardtii var. adelaidensis Poelln.
- Haworthiopsis coarctata var. adelaidensis (Poelln.) G.D.Rowley
- Haworthia coarctata f. bellula (G.G.Sm.) Pilbeam
- Haworthia reinwardtii var. riebeekensis G.G.Sm.
Haworthia coarctata f. greenii (Baker) M.B.Bayer
Haworthia Revisited 172 1999.
- Haworthia coarctata f. greenii (Baker) M.B.Bayer
- Catevala greenii (Baker) Kuntze
- Haworthia coarctata var. greenii (Baker) M.B.Bayer
- Haworthia greenii Baker
- Haworthia reinwardtii var. greenii (Baker) Halda
- Haworthia greenii f. bakeri Resende
- Haworthia greenii f. minor Resende
- Haworthia peacockii Baker
- Catevala peacockii (Baker) Kuntze
Haworthia coarctata var. tenuis (G.G.Sm.) M.B.Bayer
Natl. Cact. Succ. J. 28: 86 1973.
- Haworthia coarctata var. tenuis (G.G.Sm.) M.B.Bayer
Description: Haworthia coarctata is a medium-sized, stem forming, species that consist of columnar rosettes dotted with white, slightly raised, tubercles (protuberances on the leaves); the plant blush bronze when grown in bright light (but if they turn orange red they are getting too much). It is well known and instantly recognisable and it is also one of the least variable of the haworthias. This leafy stemmed Haworthia is well known, being somewhat easy to grow and standing considerable abuse.
Habit: This is a small evergreen tall rosette-succulent and forms dense clusters.
Rosette: Columnar, tight, 5-20 cm tall, offsetting from the base. The leaves are seemingly arranged in many spiral rows around the stem.
Leaves:* 4-6 cm long, triangular-lanceolate, tips incurved, shining green, turning red in full-sun with greenish white slightly raised, rounded tubercles in longitudinal or sometimes transverse rows; density of tubercles very variable.
Inflorescence (racemes): Up to 30 cm tall, usually unbranched, few-flowered. The flowers are white tubular.
Blooming season: Spring to summer.
Similar species: Haworthia coarctata has been very often confused with Haworthia reinwardtii in the past. The leaves of H. coarctata are fatter, smaller and more smoothly rounded and tends to form less and more open spirals. H. reinwardtii the laves are densely packed, clasping, and thinner in transversal section. If a straight line is drawn across the H. reinwardtii stem and the leaves that lie opposite the line counted, the result is often 10. If repeated with H. coarctata the answer is often 5. Both species have white tubercles on the outer (abaxial) leaf surface, usually smaller, more smoothly rounded and diffused in H. coarctata, more prominent, whiter and often in cross bands in H. reinwardtii. However, at least in some part of its range, populations with intermediate characteristics are found, and it is often difficult to distinguish what is H. coarctata and what is already H. reinwardtii.
Subspecies, varieties, forms and cultivars of plants belonging to the Haworthia coarctata group
- Haworthia baccata G.G.Sm.: (= H. coarctata v. coarctata) has pearllike slightly raised little tubercles, the plant blush bronze when grown in bright light. Distribution: Southwest of Stutterheim, Cape Province.
- Haworthia coarctata Haw.: forms columnar rosettes up to 20 cm tall dotted with white, slightly raised tubercles and forms dense clusters. Distribution: farms around Grahamstown.
- Haworthia coarctata var. adelaidensis (Poelln.) M.B.Bayer: is a smaller element with rosette up to 13 cm tall with narrow leaves. Distribution: originally collected at Grahamstown (not Adelaide).
- Haworthia coarctata f. chalwinii (Marloth & A.Berger) Pilbeam: (= H. coarctata v. coarctata) has small and firmer leaves. Distribution: Graaff-Reinet in the vicinity of the Kowie River, Eastern Cape.
- Haworthia coarctata f. greenii (Baker) M.B.Bayer: is a smooth form. Distribution: Howieson's Poort.
- Haworthia coarctata var. tenuis (G.G.Sm.) M.B.Bayer: has rosettes half the diameter of var. coarctata up to 45 cm tall trailing and rooting where they touch the soil. Distribution: Harvestvale on the Bushmans River.
Notes: Haworthia are predominantly rosette-shaped species but Haworthia coarctata is one of the few plants in the genus to form clumps of tough leafy columns.
Bibliography: Major references and further lectures
1) Debra Lee Baldwin “Succulent Container Gardens: Design Eye-Catching Displays with 350 Easy-Care Plants” Timber Press, 20/gen/2010
2) John Robert Brown “Unusual Plants: 110 Spectacular Photographs of Succulents” Abbey Garden Press, 1954
3) Rudolf Marloth “The flora of South Africa: with synopical tables of the genera of the higher plants” Volume 4 Darter bros. & co., 1915
4) Gordon D. Rowley “The illustrated encyclopedia of succulents” Crown Publishers, 01/Aug/1978
5) Urs Eggli “Illustrated Handbook of Succulent Plants: Monocotyledons” Springer, 2001
6) 3) Charles L. Scott “The genus Haworthia (Liliaceae): a taxonomic revision” Aloe Books, 1985
7) Stuart Max Walters “The European Garden Flora: Pteridophyta, Gymbospermae, Angiospermae-Monocotyledons” Cambridge University Press, 1984
8) M. B. Bayer “The new Haworthia handbook” National Botanic Gardens of South Africa, 1982
9) John Pilbeam “Haworthia and Astroloba: A Collector's Guide” B. T. Batsford Limited, 1983
10) Bruce Bayer “Haworthia revisited: a revision of the genus” Umdaus Press, 1999
11) Bayer, M.B and van Jaarsveld, E. ”Haworthia. in Illustrated Handbook of Succulent Plants: Monocotyledons.” Springer, Berlin. 2001
12) “Haworthia coarctata Haw.” <http://haworthia-gasteria.blogspot.it>. Downloaded on 09 March 2014.
Cultivation and Propagation: Haworthia coarctata 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 coarctata 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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