Eriosyce
Eriosyce is a broadly circumscribed genus of globular cacti native to Chile and neighbouring parts of Peru and Argentina. As redefined by modern taxonomists it is a large "umbrella" genus that now absorbs several once-separate groups — including Neoporteria, Islaya, Neochilenia, Pyrrhocactus, Horridocactus and Thelocephala — and so spans an enormous range of forms, from tiny tuberous-rooted dwarfs barely breaking the soil to large, heavily spined globes. Its members share funnel-shaped flowers borne at the crown and a fondness for the lean, mineral soils of the Andean foothills and coastal deserts.
Description
Because Eriosyce brings together so many former genera, no single description fits every species, but a few threads run through the group. Bodies are usually solitary and globular to shortly cylindrical, ribbed and set with prominent, often woolly areoles that carry stiff spines — in some species short and comb-like, in others long, curved and formidable. Colour ranges from fresh green through grey-green to almost black or purplish in strong light.
The flowers are the genus's most consistent feature: funnel- to bell-shaped, emerging from the woolly apex, and running through shades of yellow, pink, red and carmine. Many of the plants formerly placed in Neoporteria open their pink flowers only partly, so the blooms look almost tubular. The fruits are typically hollow, thin-walled capsules that split or dry to release the small seeds. A number of the dwarf species (the old Thelocephala group) sit atop a thick, carrot-like taproot that stores water and lets the whole plant retract into the ground during drought.
Distribution and habitat
The genus is centred on Chile, where it is one of the signature cactus groups of the country. Its range runs from the hyper-arid coastal fog deserts of the north — home to the former Islaya species, which rely heavily on maritime mist — southward and up into the dry Andean foothills, with a handful of species reaching adjacent Peru and Argentina. Plants grow in gritty, fast-draining mineral ground, often on rocky slopes or gravel flats exposed to intense sun, cool nights and long dry spells. Many populations are localised and some are threatened by grazing, mining and collection; like all cacti the genus is listed under CITES Appendix II, so nursery-grown plants should be favoured over wild material.
Notable species
- Eriosyce aurata — a large, barrel-like species with long amber to reddish spines, one of the giants of the genus.
- Eriosyce subgibbosa — a widely grown former Neoporteria, with dense spines and rich pink, half-open flowers.
- Eriosyce senilis — noted for long, soft, twisting spines that cloak the body in white or grey.
- Eriosyce napina — a small, taprooted dwarf (the old Thelocephala type) that all but disappears into the soil.
- Eriosyce islayensis — a coastal-desert species (formerly Islaya) adapted to survive largely on fog moisture.
- Eriosyce paucicostata — a grey-bodied, few-ribbed globe of the northern Chilean deserts.
Cultivation
Eriosyce are prized by collectors of South American cacti and, given the right conditions, are not difficult — but they are firmly plants for the dry, bright end of the greenhouse. Grow them in a very free-draining, mostly mineral mix with plenty of grit or pumice, in the brightest light you can offer; strong light keeps them compact and brings out the best spine and body colour. Water thoroughly during the growing season once the soil has dried, then let it dry again, and keep plants cool and completely dry through winter to prevent rot and to encourage flowering. See Watering and Repotting for general technique.
The taprooted dwarf species need extra care: a deep pot to accommodate the storage root and especially cautious watering, as their fleshy roots are quick to rot in damp compost. Most Eriosyce tolerate cool winter temperatures well as long as they stay dry, but they resent prolonged wet cold.
In cultivation
Because the genus is so broad, growers often still know their plants by the older names — a plant may be sold as a Neoporteria or Neochilenia even though it now sits within Eriosyce. There are few named horticultural cultivars in the sense familiar from Astrophytum; instead, interest lies in the natural diversity of spine form, body colour and flower shade across the many species and their populations. The genus is propagated overwhelmingly from seed, which germinates readily on a warm, gritty surface; offsets are uncommon, and slow or difficult seedlings are sometimes grafted to build size before being grown on their own roots.
See also
- Cactaceae — the cactus family
- Astrophytum — another popular globular-cactus genus
- Soil and potting mix · Watering · Repotting · Propagation — seed · Grafting · Pests and diseases