Astrophytum 'Hakujo'
| Light | As for the parent species — bright light; grafted plants tolerate slightly less |
|---|---|
| Water | Sparingly; allow to dry fully between waterings, dry rest in winter |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; USDA zones 9b–11 |
| Propagation | Vegetative offsets or grafting to fix the mutation; seed rarely comes true |
| Toxicity | Non-toxic to cats and dogs |
Astrophytum 'Hakujo is a Japanese-named mutant selection of Astrophytum — most often built on Astrophytum asterias (Kabuto) or Astrophytum myriostigma (Bishop's Cap) — in which the woolly areoles fuse together into continuous raised white ridges that run along the ribs, giving the plant a seamed, ridged appearance. The name is Japanese for the white line or ridge (haku, white) formed by the fused wool along the ribs, and in the trade the same plants are sold under a handful of colourful nicknames.
Description
Where a normal Astrophytum carries its wool in discrete tufted areoles spaced along the ribs, 'Hakujo' plants have those areoles run together into an unbroken, slightly proud line of white felt down each rib. The result is a body crossed by raised, seamed white ridges that can be crisp and regular or wandering and irregular from plant to plant. On an asterias-based 'Hakujo' (the popular Hakujo Kabuto) the low, spineless disc keeps its flattened shape but gains bold white seams across the ribs; on a myriostigma-based plant the taller columnar-to-globular body shows the same continuous ridging. The degree of flecking and the neatness of the ridges vary widely, so selected clones differ noticeably in appearance. Flowers, when produced, are the usual Astrophytum yellow, often with a red throat depending on the parent.
Cultivation
Care follows the parent species — see Astrophytum asterias or Astrophytum myriostigma for the specifics. In short: bright light, a lean fast-draining mineral mix, careful watering with a full dry-down between drinks, and a dry, cool winter rest. A couple of points are particular to this mutant. Many 'Hakujo' plants are grown grafted (commonly onto a vigorous columnar stock) to speed them along and to keep weaker or slow clones healthy; a grafted plant will grow faster and may want slightly gentler light than a plant on its own roots. Because the fused wool holds moisture against the body, water at the roots rather than overhead and keep good air movement to avoid rot lodging in the ridges.
Propagation
'Hakujo' does not reliably come true from seed — the ridged mutation is unstable, so seedlings from a 'Hakujo' mother are a mix of ridged and ordinary plants. To keep the trait, growers propagate vegetatively: remove and root any offsets, or (more usually) graft a pup or a cut top onto stock — see Grafting. Enthusiasts do also raise batches from seed and select the best-ridged seedlings, which is how new and improved 'Hakujo' lines are developed.
See also
- Astrophytum — the genus overview
- Astrophytum asterias · Astrophytum myriostigma — the usual parent species
- Grafting · Soil and potting mix · Watering · Propagation — seed