Blossfeldia
Blossfeldia is a monotypic genus of the cactus family Cactaceae, containing the single species Blossfeldia liliputana — widely regarded as the smallest cactus in the world. A spineless, button-like plant just a centimetre or two across, it grows wedged into shady rock crevices high in the Andes of Argentina and Bolivia, where it survives extremes of drought that would kill almost any other cactus.
Description
Blossfeldia plants are tiny, soft, disc- to button-shaped bodies rarely more than 1–2 cm across, lacking spines, ribs and the tubercles that structure most other cacti. The pale grey-green skin is smooth and matte, with small, evenly scattered areoles bearing little more than fine felt. In the wild, plants pull down into rock cracks and are so flat and unassuming that they are easily overlooked among the surrounding stone.
Older plants often cluster, budding new heads from the base to form low, congested mats of many small bodies. The flowers are correspondingly small — pale, creamy-white to faintly pink, opening singly near the crown. The genus is remarkable botanically for its dust-like seeds — among the smallest of any cactus — and for an extraordinary tolerance of desiccation, more often associated with mosses and lichens than with cacti, that lets the shrivelled bodies survive prolonged drought and swell again when moisture returns.
Distribution
Blossfeldia is native to the high Andes of northwestern Argentina and southern Bolivia, where it grows at considerable elevation on cliffs and rocky slopes. It is a true crevice-dweller, rooting into narrow cracks in vertical or steeply inclined rock, often near seasonal seepage that briefly wets the stone. This sheltered niche gives it some shade and protection from the fiercest sun and wind, while exposing it to long periods of complete drought.
The plant is famous for its resurrection-like drought tolerance: bodies can shrivel almost flat and appear dead through the dry season, then rehydrate and swell again when moisture returns, a survival strategy more often associated with mosses and lichens than with cacti.
Notable species
Being monotypic, the genus contains only one accepted species:
- Blossfeldia liliputana — the sole species, and the type; the smallest known cactus. Several regional forms and former "species" once described within Blossfeldia are now generally treated as variants of this one variable plant.
Cultivation
Blossfeldia has a reputation as a challenging plant to grow on its own roots, largely because of its minute size, slow growth and easily-rotted body. It wants a very open, gritty, mostly mineral mix, sharp drainage and careful, restrained watering — enough to prevent total desiccation in the growing season, but never so much that the little body sits wet. Bright but not scorching light and good airflow suit it best, echoing its shaded crevice habitat.
Because seedlings are so tiny and slow, many growers raise Blossfeldia by grafting onto a vigorous rootstock such as Pereskiopsis or an Echinopsis-type stock. Grafted plants grow far faster and offset freely, though they take on a plumper, less characteristic look than lean plants grown hard on their own roots. See Repotting for handling such small plants.
Propagation
The plant can be raised from its exceptionally fine seed, sown on a mineral surface and kept humid and warm; germination is possible but the dust-like seedlings demand patience and steady care. More commonly, established clumps are divided or individual heads removed and rooted, or seedlings are grafted to accelerate growth. See Propagation — seed and Propagation — offsets for general technique.
Hobby notes
Blossfeldia is a connoisseur's plant, prized by collectors of miniature and "difficult" cacti rather than grown as a beginner's windowsill subject. There are no showy named cultivars in the Astrophytum sense; interest instead centres on well-grown, characterful clumps and on the various geographic forms. Like all cacti it is covered by CITES Appendix II listing, so buy nursery-propagated material and never wild-collected plants.
See also
- Blossfeldia liliputana — the single species
- Grafting · Soil and potting mix · Watering · Propagation — seed · Propagation — offsets