Echinopsis
Echinopsis is a large genus of globular to short-columnar cacti native to South America, celebrated among growers for producing enormous, often nocturnal, funnel-shaped flowers that can dwarf the plant bearing them. The genus takes in many old hobby favourites once scattered across genera such as Lobivia, Trichocereus, Chamaecereus and Pseudolobivia; the tall, columnar "San Pedro" plants historically folded into Echinopsis are now usually split back out as Trichocereus. Its members earn common names like sea urchin cactus, Easter lily cactus and hedgehog cactus.
Description
Most Echinopsis are small to medium cacti with strongly ribbed, spherical to barrel-shaped or shortly columnar bodies, ranging from ping-pong-ball miniatures to clustering mounds and stout column-formers. The ribs are typically well defined and carry evenly spaced areoles bearing spines that vary from short and stiff to long and needle-like depending on the species.
The genus is defined above all by its flowers. Large, funnel- or trumpet-shaped and carried on a long, hairy or scaly floral tube, the blooms open from the sides or crown of the plant and are often startlingly large relative to the body. Many species flower at night or in the cool of early morning, are white and sweetly scented (a hallmark of moth-pollinated species), while others — particularly the former Lobivia element — open by day in vivid reds, oranges, yellows and pinks. Individual flowers are frequently short-lived, lasting only a day or two, but plants often bloom in flushes.
Distribution and habitat
Echinopsis is distributed widely across South America, centred on Argentina, Bolivia, Peru, Chile, Uruguay, Paraguay and southern Brazil. Species occupy a broad range of habitats, from lowland grassland and thornscrub to high-altitude Andean slopes, where the day-flowering, brightly coloured species in particular endure intense sun, cold nights and a strongly seasonal climate. This wide ecological range is part of why the genus is so accommodating in cultivation.
Notable species
- Echinopsis eyriesii — an old-fashioned, freely offsetting species with huge, white, night-scented trumpet flowers.
- Echinopsis oxygona — a robust clustering species producing large pink to lilac blooms.
- Echinopsis subdenudata — the "Easter lily cactus", an almost spineless, woolly-areoled favourite grown for its big white flowers.
- Echinopsis chamaecereus — the "peanut cactus" (formerly Chamaecereus silvestrii), a sprawling, finger-like clusterer with bright orange-red flowers.
- Echinopsis calochlora — a small, globular Brazilian species that blooms readily when young.
The many day-flowering species formerly placed in Lobivia are also treated here by most authorities, and remain among the most rewarding small flowering cacti for the windowsill. The tall columnar species such as Trichocereus pachanoi and Trichocereus bridgesii are, in current hobby usage, generally kept under Trichocereus.
Cultivation
As a group, Echinopsis are among the easiest and most forgiving cacti to grow, which accounts for their long popularity. Give them a free-draining, mostly mineral potting mix and bright light — full sun for most, with a little shade from the fiercest afternoon glare for softer-bodied or high-altitude species. Water generously during the growing season once the soil has dried, then keep the plants cool and nearly dry through winter. A cold, dry winter rest is the single most important factor in encouraging the spectacular flowering the genus is grown for. See Watering and Repotting for general technique.
Most species are hardy only above freezing, though many tolerate a light touch of frost if kept bone dry; treat them as tender unless you know a particular species to be tougher. They are heavy feeders when in growth and reward a dilute feed through spring and summer.
Propagation
The clustering species are the simplest of all cacti to increase: they throw abundant offsets that can be twisted or cut off, allowed to callus for a few days, and rooted in barely moist mix. Larger columnar or solitary types can be grown from cuttings, and the whole genus grows readily from seed, which is also how new hybrids are raised. See also Grafting, which is sometimes used to bring slow or hard-to-root seedlings on quickly.
Cultivars and hybrids
Echinopsis has been hybridised enthusiastically, above all by crossing the large-flowered night-bloomers with the vividly coloured day-flowering (former Lobivia) species. The result is a huge range of named hybrids — often marketed simply as "Echinopsis hybrids" — grown for spectacular, saucer-sized flowers in almost every colour but true blue, frequently with contrasting throats and ruffled petals. These hybrids retain the easy temperament of the genus and are excellent choices for growers who want maximum flower for minimum fuss.
Common problems
- Rot — the usual cause of loss, almost always from a wet, cold winter or a slow-draining mix; the body softens and discolours from the base.
- Etiolation — too little light makes the body pale and stretch, and discourages flowering.
- Shy flowering — most often the result of skipping the cool, dry winter rest the genus needs to set buds.
- Pests — mealybugs (white fluff in the areoles and among offsets) and red spider mites are the common culprits; see Pests and diseases.
See also
- Trichocereus — the columnar "San Pedro" group now usually split from Echinopsis
- Cactaceae — the cactus family
- Soil and potting mix · Watering · Repotting · Propagation - offsets · Propagation - seed · Grafting