The Desert Garden of Huntington Botanical Gardens (in San Marino, California) contains thousands of taxa of dryland-adapted plants. In my opinion, it is the botanical highlight of Huntington BG.

This particular “mother of hundreds” cactus is one of Huntington's oldest living accessions (assuming accession numbers are given sequentially by chronology) – accession number 948. The highest accession number I've recorded from my visit was 93643. Considering the Desert Garden was started in 1907-1908, and assuming accessions were recorded from the beginning (not a safe assumption, I've learned), it's possible that this particular plant is nearly a century old.

Mammillaria compressa is native to northeastern (subspecies centralifera) and central Mexico (subspecies compressa). Details on both of these taxa can be found on the wonderful Mammillarias.net (here and here). Both pages show the diversity of form of these subspecies through photographs.

Lastly, local readers might be interested to attend the Freeman Patterson lecture next week in Vancouver, “A Call to Creativity”. A big thank you to Jennifer (aka colour@Flickr) for pointing it out to me, as I would have missed it.