Lithops spp: stolid prima donnas, down-to-earth yet delicate

Lithops sp, tentatively L marmorata, on 2nd day of bloom.
The largest body here is under 2 inches at its widest.

When you walk down the aisle of a plant show or even a nursery department in a big-box store, certain succulents reach out and knock you over. They barely look like plants. In fact, sometimes it's hard to believe they're even alive. Lithops are tiny but they fall into this drop-dead category.

With a name from the Greek for stone and eye or face, Lithops or "Living Stones" are small plants native to the dry Western Cape region of Southern Africa. They are in the same family (Aizoiaceae) as ice plants, also originally from Southern Africa and spread the world over by human travel and other transport.

Unlike their ice plant cousins, cultivated for centuries and easy to care for, Lithops are widely known only since the 1950s (with the collecting and cataloging work of Desmond and Naureen Cole). Not only did they emerge from obscurity recently — they also have a reputation for being somewhat difficult for amateur cacti and succulents growers. (I have killed quite a few of them, and the Lithops flowers pictured are some of my first.) Lithops are adapted to a dry existence, and if watered too much or at the wrong time they can succumb quickly to that omnipresent nemesis of succulent fanciers: rot.

Lithops care is less of a puzzle once you learn a basic lesson about about their special needs in winter: briefly, don't feed or water them. They are not truly dormant, but they are busy with a small, vital, inner task: growing a new leaf pair in the center of the plant. As the new pair (or pairs) grow, they absorb the nutrients from the previous year's pair. The outer pair shrivels and the inner pair (or pairs) emerges from the seam between the two dying leaves. If you water them during this period, you risk rotting the plant or preventing the outer leaves from being absorbed. Even if the plant survives, this can lead to a misshapen and unnatural look, living blobs instead of neat roundish tiles.

Mid-October, the time of this post, is prime time for Lithops flowers. They like to make hay while the sun still shines.

References

Lithops gallery

Lithops.info 

Cole, Desmond; Cole, Naureen (2005). Lithops—Flowering Stones. Cactus & Co. 368 pages (20.7 × 29.5 cm), 644 col. + 5 b/w photos, 3 col. + 85 b/w drawings, 7 maps, 98 habitat photos. ISBN-10 88-900511-7-5. ISBN-13 978-88-900511-7-3

Hammer, Steven (2010). Lithops: Treasures of the Veld. 2nd Edition. BCCS. Softbound; 156 pages; 238 photos. ISBN-10: 0902099922. ISBN-13: 978-0902099920.

Shimada, Yasuhiko (2001). The Genus Lithops. Dobun Shoin. 240 pages (19 × 26.5 cm), 437 col. photos, 1 b/w map. ISBN-10 4-8103-4066-X.