Ortegocactus
Ortegocactus is a cactus genus from the Mexican state of Oaxaca that contains only a single species, Ortegocactus macdougallii. It is a small, slow-growing plant instantly recognisable by its distinctive bluish-grey to grey-green body dotted with dark-tipped spine clusters — a look that has made it a much sought-after prize among collectors, and one with a reputation for being a little temperamental in cultivation.
Description
Ortegocactus is a diminutive genus of low, clustering globular cactus. The stems are usually only a few centimetres across, eventually forming small clumps by offsetting from the base. The body colour is the genus's signature feature: a soft, chalky blue-green to grey-green, an unusual shade among cacti, thanks to a fine waxy (pruinose) bloom on the epidermis. Small woolly areoles carry short radial spines that are whitish with dark tips, together with a single dark central spine, giving the plant a neatly speckled appearance.
The root system is surprisingly extensive and fibrous relative to the modest body above it, an adaptation to the plant's dry, rocky home. Flowers appear from near the crown and are bright glossy yellow, opening in the warmer part of the growing season. The whole plant rarely exceeds a few centimetres in height, making it a classic small "windowsill" collector's cactus.
Distribution
The genus is endemic to a very restricted area in the state of Oaxaca, in southern Mexico. There it grows in open, rocky ground on limestone and among low scrub at moderate elevation, rooting in shallow, gritty, extremely free-draining substrate and enduring bright sun, seasonal drought and cool nights. Its tiny natural range makes it a plant of considerable conservation interest, and — as with the whole cactus family — wild collection is discouraged; garden and nursery material should always be nursery-propagated rather than wild-collected.
Notable species
Being a monotypic genus, Ortegocactus contains just one species:
- Ortegocactus macdougallii — the sole species, prized for its unique blue-grey body and cheerful yellow flowers.
Cultivation
Ortegocactus has a reputation among growers as a rewarding but slightly fussy subject. The two things it dislikes most are stale, water-retentive compost and any hint of standing moisture around the base. Grow it in a very open, mostly mineral mix with plenty of grit or pumice, in a snug pot that lets the roots dry quickly. Give it strong light — this brings out the best body colour — with just a little protection from the most scorching midday sun.
Water thoughtfully during the growing season, letting the mix dry out completely between soakings, and keep the plant dry and cool through winter. See Watering and Repotting for general technique. The species is naturally slow, and its rather sensitive roots resent disturbance, so repot only when necessary and be gentle with them.
A common quirk in cultivation is the appearance of rusty orange or corky spotting on the epidermis, especially toward the base of older stems. This is largely cosmetic and is seen on wild as well as cultivated plants, appearing to be a feature of natural maturity rather than a disease; keeping the plant lean, airy and correctly watered keeps it looking its best.
Because of its slow growth and delicate root system, some growers maintain Ortegocactus as a grafted plant on a hardier rootstock to speed it along and sidestep root troubles, then may return it to its own roots later. See Grafting for the method.
Propagation
Fresh seed is the usual way to raise new plants, sown on a warm, mineral surface and kept humid until germination (see Propagation — seed). Established clumps can also be increased by removing rooted offsets from the base, though the plant is not a prolific pupper (see Propagation — offsets). Grafting is widely used both to rescue plants with root problems and to grow seedlings on more quickly (see Grafting).
Cultivar notes
As a rare, slow, single-species genus, Ortegocactus has not been developed into the sprawling cultivar lines seen in some collector cacti. Interest instead centres on well-grown, cleanly coloured specimens and on the occasional variegated or crested plant, which are highly sought after and usually maintained by grafting.
Common problems
- Rot — the number one killer; caused by a slow-draining mix or overwatering, especially in cool or damp conditions. The plant softens and discolours from the base.
- Corky or rusty spotting — orange, scabby marks on the skin, largely a cosmetic feature of natural maturity rather than true disease, and seen on wild plants too.
- Root loss — the sensitive roots can die back after cold-wet spells or rough repotting, after which grafting may be the surest way to save the plant.
- Pests — mealybugs (white fluff in the areoles, including on the roots) and red spider mites are the usual offenders; see Pests and diseases.
See also
- Ortegocactus macdougallii — the single species in the genus
- Grafting · Soil and potting mix · Watering · Repotting
- Propagation — seed · Propagation — offsets · Pests and diseases