Living Stones

Living Stones, Lithops spp.

Native to the dry, southern regions of Africa, Lithops is a genus of succulent that has taken a lesser known defense against herbivores: fading into the background. These plants are also known as Living Stones for their ability to blend in to their environment. Their appeal is heightened for herbivores during the long, dry season as the leaves of Lithops and others in the family Aizoaceae are adapted to hold water. With only two very succulent leaves, it is of greater important to prevent predation.

The particular genus Lithops was first discovered in 1811 by Thomas Burchell. Its ability to blend in almost fooled Burchell who originally thought the plant a curiously shaped pebble. No other part of the plant is exposed to the surface.

The peculiarity of the leaves goes beyond appearance. The actual photosynthetic tissue is located on the inner surface of the leaf. In order to reach the tissue, sunlight travels through what is known as windows. These transparent sections allow light striking it to be diffused by crystals of calcium oxalate to allow maximum exposure to the photosynthetic tissue. The gas exchange of the plant occurs underground so the stomates are not exposed to wind or sun allowing minimal water loss.

Unfortunately, the bizarre appearance and unique characteristics of Living Stones has made them popular with collectors. Many species have been driven to the verge of extinction by collectors. They are now protect by law, but ones grown from seed or other lawful means are available in nursery and gardening centers.

This is a direct copy of my earlier post on Google+ found here. The photo is one from a local nursery - I've not had an opportunity to find these in the wild yet! There will be no posts next week, but will resume (likely briefly) the week after. It's a busy time of year for me, but I'm doing my best :)