Trichocereus candicans / Echinopsis candicans
This is a large, sprawling, columnar cactus from central South America. The long-spined plant is visible behind the flowers.
It flowers at night throughout warm weather. I will try to take a photo tomorrow morning if the flower is still open. They don't last long when it's hot; it's 1 am now, and the official temperature is still 93 F / 34C. Here at my house it was 113 F / 45C this afternoon. Relative humidity was only 6% today, and the dew point is below freezing, so evaporative coolers work very well.
Most candicans in the US have white flowers. Other colors are reported to occur in habitat. Flowers of this species have a faint, fresh scent; other Echinopsis species are scentless, and still others heavily scented. They are easily propagated by stem cuttings, so there are probably very few candicans clones in the US.
Stems are about 4" / 10cm in diameter. The commonest form seen in cultivation in the US has short spines, giving the plant a formal and smooth appearance. This individual has extremely long spines, giving it a shaggy look.
The stems start out upright, and sprawl to the ground as they enlarge. Plants continue to make new stems from the center of the plant. The plant grows to resemble an octopus, with ever-elongating stems growing out from the center. I have seen old plants in metro Phoenix that cover a circle 12 feet / 3.6 meters in diameter. They may open hundreds of flowers in one night.
Flowers open after dark, and close the next day when it becomes hot. In cooler-summer climates, or picked and brought into a refrigerator, they last more than a day. For comparison, I wear size 8 1/2 gloves. This is an enormous flower, one of the largest flowers in the plant world. It is second among cacti to Selenicereus species, which are also white, nocturnal, long-tubed and moth-pollinated.
A number of closely-related cactus genera have been lumped into Echinopsis based on some DNA studies. Most hobbyists still use the old generic names; they formed groups easily distinguishable by characteristics important to horticulturists. All have varying amounts of hair on the buds, which easily distinguishes them from another South American cactus genus popular with hobbyists, Gymnocalycium (which means naked cup, for the hairless buds.)
Hobbyists formerly called plants with globular stems, most of which offset profusely, Echinopsis. Stem tips are blunt and convex. They open their long-tubed flowers near midnight, and they close the next day in hot climates. Flowers are borne from the sides of the stems near the apex; they can be white through any shade of yellow, orange, red or pink, and may be scented. They have been hybridized extensively. Echinopsis are among the easiest of all cacti to grow and bloom in a wide range of climates and indoor temperatures. They flower easily in a 3" / 7.5cm pot. They tolerate substantial overnight frosts if they warm above freezing the next day. They are not suitable for outdoor growing in cold-winter climates, though. They are susceptible to spider mites in cultivation.
Globular cacti with day-opening, unscented, short-tubed flowers in brilliant colors, almost all bearing a black ring in the throat, were formerly called Lobivia. The growing point of the stem is distinctly depressed into the stem. Flowers are borne from the shoulders of the tops of the plants, on the highest portion of stem. These are bee pollinated. Plants tend to be solitary. They are from high in the Andes, on both sides of the peaks, and not easy to grow in our high heat. They prefer cool nights all year. However, they cannot tolerate frost; they are found below the frost zone. Lobivias do great in most cold-winter climates if brought indoors for the winter. They flower through warm weather and stay small, up to perhaps the size of a softball for an old plant. They are less susceptible to spider mites.
Columnar plants were called Trichocereus (hairy cereus, because the outsides of flowers are very hairy.) A few are tall, stocky and upright plants greatly resembling the saguaros of Arizona. Others have relatively thin, sprawling stems, and others are thicker. A few stay upright. All have stems with convex tips. Almost all have white nocturnal flowers, though some populations have other colors, chiefly reds and pinks. There are a few species with day-opening flowers. Best known of these is T. huascha, which has smaller flowers than T. candicans. They are brilliantly colored, anywhere from magenta to yellow. Trichocereus flowers can be borne anywhere along the stem; commonest is near the tip. Many Trichocereus tolerate severe frosts in habitat if dry, but they cannot tolerate weeks of subzero weather. These have been used as landscape plants in the southwest of the USA. They are too large for most people to grow in cold-winter areas. One species, T. spachianus (Echinopsis spachianus) seems to require fairly low winter temperatures to bloom. It almost never blooms in metro Phoenix, but often blooms in inland southern California. There are a lot of Trichocereus hybrids, as well.
Tiny, globular plants once known as Rebutia and Sulcorebutia are also high-elevation, cool-growing plants that don't tolerate frost. The main difference between them is the Sulcos often have extensive, tuber-like underground stems, and plant bodies are usually a little larger than Rebutias. In habitat they are always solitary, found in deep grass or moss. Stems have a concave, recessed tip. They are covered with brilliant small flowers in spring; flowers emerge far down on the stem, almost at ground level. They have long tubes, so flowers typically open above the stems. In cultivation they offset, often profusely. A large clump in bloom is amazing to see. These are hard to grow in our hot summers. Europeans grow them exceptionally well, and they also do well in our midwest and northeast. The former Rebutias require very short pots; people recommend taking standard plastic pots and cutting them down to half-height. Sulcos take standard-height pots. They are highly susceptible to spider mites. They must have a dry, cool winter, with water withheld until buds are very well-formed, or they will not flower.
Last edited by estación seca; 06-19-2017 at 04:58 PM..
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