Browningia
Browningia is a genus of columnar and tree-like cacti from the arid Andean valleys and coastal deserts of Peru, Chile and Bolivia. The genus is best known for a handful of species whose stems are coated in a striking blue-grey waxy bloom, giving them an almost surreal, powder-blue appearance in habitat. Several were once separated into the genera Azureocereus and Gymnocereus, but these are now generally folded into Browningia.
Description
Browningia species are large, slow-growing cacti that range from tall single columns to well-branched, tree-like plants with a distinct woody trunk. Mature specimens can reach several metres in height, making them among the more imposing cacti of the Andes. The stems are ribbed and, in the most sought-after species, overlaid with a pale blue to blue-grey waxy coating that rubs away where the plant is handled.
A curious feature of some Browningia is that spination changes dramatically with age: juvenile stems may be heavily and fiercely spined, while the upper, flowering parts of a mature plant become almost spineless. Flowers are generally nocturnal or open toward evening, tubular to funnel-shaped, and often scaly on the outside; they are followed by fleshy fruits. Because these are large plants that flower only at maturity, blooms are an uncommon sight in cultivation.
Distribution
The genus is centred on the western slopes of the Andes and the adjacent coastal deserts, from Peru south into northern Chile, with some representation in Bolivia. Plants typically grow on rocky, well-drained slopes and in dry inter-Andean valleys, in regions that are hot and bright by day, cooler at night, and receive little rainfall. The blue waxy bloom of several species is thought to help reflect the intense high-altitude sunlight.
Notable species
- Browningia hertlingiana — perhaps the most famous, prized for its intensely blue, waxy columnar stems; a favourite among collectors of blue cacti.
- Browningia candelaris — the candelabra cactus, a tree-like species with a stout woody trunk and a crown of upward-reaching branches, fiercely spined when young.
- Browningia columnaris — a tall, strongly columnar species from Peru.
Several species formerly placed in Azureocereus (notably the blue-stemmed forms) and Gymnocereus are today usually treated within Browningia.
Cultivation
Browningia are grown much as other large desert columnar cacti. They want a very free-draining, mostly mineral mix, strong light, and warmth. Give them as much sun as you can — bright light not only keeps growth compact but also encourages the best blue colouring in species such as B. hertlingiana. Water generously during the warm growing season once the soil has dried, then keep the plants dry and cool through winter; they are not frost-hardy and resent cold, wet roots. See Watering and Repotting for general technique.
Growth is slow, and these plants ultimately become large, so they are better suited to growers with space (or a greenhouse border) than to a crowded windowsill. Handle the waxy blue species carefully — the bloom is easily marked by fingerprints and does not regrow on old skin.
Propagation
The usual method is seed, which germinates readily under warm, bright, humid conditions and is how most collection plants are raised. Large stems or branches can also be taken as cuttings; allow the cut to callus well before rooting into a gritty mix. Vigorous seedlings are sometimes grafted onto a robust rootstock to speed early growth.
Cultivation and hobby notes
In the hobby, Browningia is grown far more for its architecture and colour than for flowers, which are seldom seen on potted plants. B. hertlingiana in particular is a centrepiece of "blue cactus" collections. There are few named cultivars; interest centres instead on selecting well-coloured, cleanly grown seed-raised plants. As with any large columnar cactus, plan ahead for the plant's eventual size and the difficulty of repotting a tall, spiny specimen.
See also
- Browningia hertlingiana · Browningia candelaris — signature species
- Grafting · Soil and potting mix · Watering · Propagation — seed · Propagation — cuttings · Repotting · Pests and diseases