Publication: Bradleya 9: 30 1991
Description
Melocactus bahiensis subs. amethystinus distinguishes from the standard Melocactus amethystinus for its more acute ribs that are triangular in cross section. Melocacti are best known for their cephalia (the cap-like structures, where the flower buds will form) and always attract attention in collections.
Habit: It is a single stemmed perennial succulent plant with determinate growth (in which the axis does not continue to elongate indefinitely being limited by the development of the cephalium).
Stem: Depressed-spherical, globose or pyramidal, light to dark green 10-21 cm tall, 11-21 cm in diameter in diameter.
Ribs: 8-12 (usually 9) acute and triangular in cross section.
Areoles: White10-24 mm apart.
Cephalium: Mostly small with many brown bristles up to 5 cm high and 6,5-8,5 cm in diameter.
Spines: Short, curved, off-white, except in the centre where the new ones are yellow, reddish brown, dark brown to black often bent or even hooked in juvenile specimens.
Central spines: 1-4 per areola, 10-53 mm long mostly straight-projecting:
Radial spines: 7-12 mostly straight. 13-50(60) mm long, the lowermost only a little longer than the others.
Flowers:18-23 mm long, 10-12 mm wide. Pericarpel 6,5-8,5 cm long with white wool and bristles.
Fruit: Berry, club-shaped up to 25 mm long, 9 mm in diameter, red to crimson on the top white or pale pink at the base.
Seeds: 1-1,35 x 1 mm somewhat tuberculate.
Origin and Habitat
Eastern Brazil (southern edge of Bahia) and northern Minas Gerais.
Altitude: 300-1000 metres above sea level.
Habitat: It grows in exposed on gneiss or ancient granite rocks on sandy quartz soils associated with shrubby and arboreal caatinga (typical savanna with rainfalls around 900 mm per annum). This reduced rocky habitats harbour a rich succulent flora comprising Pereskia aureiflora, Pereskia grandifolia var. violacea, Opuntia brasilienis, Opuntia inamoena, Tacinga braunii, PseudoacanthoSN’>4354’ alt=‘8691’>Cereus brasiliensis#SN#6631’>Pseudoacantho[[Cereus brasiliensisSN’ style=‘border:none;’>, Arrojadoa penicillata, Brasilicereus phaecanthus, Cereus jamacaru, Coleocephalocereus aureus, Coleocephalocereus purpureus, Melocactus ernestii, Melocactus violaceus, Pilosocereus cenepequei, Pilosocereus floccosus, Pilosocereus splendidus, Pilosocereus magnificus, PilosoCereus multicostatus, Pilosocereus subsimilis and SeleniSN’>7796’ alt=‘6631’>Cereus setaceus#SN#8691’>Seleni[[Cereus setaceusSN’ style=‘border:none;’>.
Cultivation and Propagation
These tropical cacti are not the easiest things to grow and aren’t plants for beginners.
Growth rate: It is a relatively rapidly growing given the best conditions.
Soils: It likes very porous standard cactus mix soil.
Repotting: The root system is weak and generally resents being repotted and can take a long time to re-establish. Use pot with good drainage.
Light: They prefer very bright light, not as much as the most arid growing cacti, but plenty nonetheless. Tends to bronze in strong light, which encourages flowering and heavy spine production.
Watering: Melocacti grow from April to October and cannot endure long stretches of total dryness, and also too much water will rot them, as their weak root systems tends to be inefficient at sucking up water from wet soil. Nonetheless, again as a result of their tropical origins, they need a fair amount of water, but allow the soil to dry quite a bit before watering again.
Fertilization: Do not feed in winter.
Hardiness: Melocactus rest from October to April but can’t stand cold, or even fairly cool temperatures, so is indispensable to keep them above 8-12°C at all times, severe damage or death occurring at temperatures that the great majority of cacti wouldn’t mind in the least and prefer more frequent water in winter than other cacti, say once a month. (but hardy to 4 C ° C for short periods). However warmth throughout the year will increase the grower’s success (minimum 12° to 20° C during rest season).
Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for:
- Red spiders: Red spiders may be effectively rubbed up by misting the vulnerable plants every day
- Mealy bugs: Mealy bugs occasionally they develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects.
- Scales: Scales are rarely a problem.
- Rot: it is only a minor problem with cacti if the plants are watered and “aired” correctly. If they are not, fungicides won’t help all that much.
Propagation: Exclusively by Seeds. Sow in February-march in a light, sandy, porous soil. Cover germinating tray with glass to prevent seed from drying out. Germination is most successful at a temperature of 18 to 22° C.
Bibliography
Major references and further lectures
-
David Yetman “The Great Cacti: Ethnobotany & Biogeography” University of Arizona Press, 2007
-
Stuart Max Walters “The European garden flora. 3.[Angiospermae], Dicotyledons. [Casuarinaceae to Aristolochiaceae]” Cambridge University Press, 1989
-
Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
-
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/Aug/2011
-
David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. “The New Cactus Lexicon” dh books, 2006
-
Taylor, N. P. “The genus Melocactus (Cactaceae) in Central and South America.” Bradleya 9: 1–80 1991
-
Urs Eggli, Leonard E. Newton “Etymological Dictionary of Succulent Plant Names” Springer, Berlin/Heidelberg 2010
-
N. L. Britton, J. N. Rose “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume III, The Carnegie Institution of Washington, Washington 1922
-
Philipp von Luetzelburg “Estudo Botanico do Nordéste.” Volume 3, 1923
-
Nigel P. Taylor, Daniela C. Zappi “CACEACEAE DO VALE DO RIO JEQUITINHONHA (MINAS GERAIS)” Acta bot. Bras. 5(1): 1991
From llifle page Melocactus grisoleoviridis
Description
Melocactus grisoleoviridis distinguishes from the standard Melocactus bahiensis subs. amethystinus for its larger green till silver body. It has also a taller cephalium with wool and brown bristles. It remembers a crowned head. Plants of this genus attract more attention in collections than those of any other cactus genera.
Stem: Depressed-spherical, globose or pyramidal, light to dark green 10-21 cm tall, 11-21 cm in diameter in diameter.
Ribs: 10-12 acute and variable in shape.
Areoles: White 10-24 mm apart.
Cephalium: Mostly small with many brown bristles up to 5 cm high and 6,5-8,5 cm in diameter.
Spines: Short, curved, off-white, except in the centre where the new ones are yellow, reddish brown, dark brown to black often bent or even hooked in juvenile specimens.
Central spines: 1-4 per areola, 10-53 mm long mostly straight-projecting:
Radial spines: 7-12 mostly straight. 13-50 mm long, the lowermost only a little longer than the others.
Flowers: 18-23 mm long, 10-12 mm wide.
Fruit: Berry, club-shaped up to 25 mm long, 9 mm in diameter, red to crimson on the top, white or pale pink at the base.
Seeds: 1-1,35 x 1 mm somewhat tuberculate.
Origin and Habitat
Itamarandiba, Northern Minas Gerais, Brazil.
Altitude: Around 850 metres above sea level.
Bibliography
Major references and further lectures
-
David Yetman “The Great Cacti: Ethnobotany & Biogeography” University of Arizona Press, 2007
-
Stuart Max Walters “The European garden flora. 3.[Angiospermae], Dicotyledons. [Casuarinaceae to Aristolochiaceae]” Cambridge University Press, 1989
-
Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
-
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/Aug/2011
-
David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. “The New Cactus Lexicon” dh books, 2006
-
Taylor, N. P. “The genus Melocactus (Cactaceae) in Central and South America.” Bradleya 9: 1–80 1991
-
Urs Eggli, Leonard E. Newton “Etymological Dictionary of Succulent Plant Names” Springer, Berlin/Heidelberg 2010
-
N. L. Britton, J. N. Rose “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume III, The Carnegie Institution of Washington, Washington 1922
-
Philipp von Luetzelburg “Estudo Botanico do Nordéste.” Volume 3, 1923
Source: Melocactus grisoleoviridis, LLIFLE - Encyclopedia of living forms, CC-BY-SA, retrieved 2026-10-25.