Lophocereus schottii
| Light | Full sun; bright light indoors |
|---|---|
| Water | Sparingly; allow to dry fully between waterings, keep dry in winter |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; USDA zones 9b–11, brief light frost tolerated |
| Propagation | Cuttings (easy) and seed |
| Toxicity | Not a listed common pet toxin, but tissues (especially the skin) contain bitter isoquinoline alkaloids — not for eating |
Lophocereus schottii, the senita cactus, is a clustering, grey-green columnar cactus native to the Sonoran Desert of Sonora and Baja California in Mexico, reaching just into southern Arizona. Mature stems develop a crown of long, bristly grey spines near their tips — the "whiskers" that give the plant its common name senita (loosely "little old one") — from which small pink night-opening flowers appear. It is best known to hobbyists through its lumpy, spineless monstrose form, the popular "totem pole cactus".
Description
Lophocereus schottii branches freely from the base to form open clumps of erect, ribbed columns, in time producing dozens of stems and reaching several metres tall in habitat. The stems are a soft grey-green, relatively slender, and carry a small number of broad, rounded ribs (usually around five to seven) set with short spines when young.
As a stem matures and reaches flowering size, the areoles near its tip change dramatically, producing dense clusters of long, twisted, grey bristle-like spines. This bristly, whiskered zone is a form of pseudocephalium and is where the plant flowers. The flowers are small, pale pink, funnel-shaped and open at night, followed by small reddish fruit.
The species is famous for its pollination biology: in the wild it depends heavily on the senita moth (Upiga virescens), which pollinates the flowers and lays its eggs on them — an obligate mutualism often compared to that of the yucca and its moth.
Distribution and habitat
The senita is a Sonoran Desert plant, widespread through the Mexican state of Sonora and down the Baja California peninsula, with populations crossing the border into southern Arizona. It grows on desert flats, bajadas and coastal plains, often alongside organ pipe and other columnar cacti, in gritty, well-drained soils under intense sun and low rainfall.
Like all cacti it is listed under CITES Appendix II, but nursery-grown plants are common and legal to own and trade.
Cultivation
Lophocereus schottii is an easy, tough columnar cactus for a hot, sunny position. Grow it in a very free-draining, mostly mineral mix and give it as much light as possible — full sun outdoors, or the brightest spot available indoors. Water thoroughly when the soil has dried out during the warm months, then keep the plant dry and cool through winter to prevent rot and to firm up the growth. See Watering and Repotting for general technique.
It is more cold-tolerant than many desert columnars, taking brief light frost once established, but it dislikes prolonged wet cold. In containers it appreciates being grown hard and repotted only when it has genuinely outgrown its pot.
Propagation
The species propagates very easily from stem cuttings: sever a branch, let the cut surface callus for a week or more in a dry, airy spot, then set it in dry mineral mix and water lightly once roots begin. It can also be grown from seed sown on a warm, gritty surface, though seedlings are slower to reach the characteristic whiskered flowering stage.
Cultivars
By far the most widely grown form is the monstrose "totem pole cactus" (often sold as L. schottii f. monstrosus). It is a spineless, largely ribless mutant whose stems are covered in smooth, irregular, lumpy bumps, growing slowly into a sculptural grey column. Because it lacks spines and produces little seed, it is maintained almost entirely from cuttings and is a favourite in low-water and modern landscape plantings. A smoother-bumped selection is sometimes distinguished as the "totem pole" proper versus a knobblier "fantasy" type.
Common problems
- Rot — the usual killer, from overwatering, a slow-draining mix, or cold wet winters; stems soften and discolour from the base.
- Etiolation — too little light causes thin, pale, weakly-ribbed growth that flops.
- Pests — mealybugs (white fluff in the areoles and roots) and scale are the most common; watch also for spider mites in hot dry indoor air. See Pests and diseases.
See also
- Lophocereus — the genus overview
- Propagation — cuttings · Soil and potting mix · Watering · Repotting