SUCCULENT SUNDAY: Haworthia tessellata, waxy windowed whorls

Haworthia tessellata 'Neat' shooting a bloom stalk. Can you see the windows in the leaf tops?

Haworthia tessellata is one of my favorite plants. At least, that's what I tell people. At least one friend has complained that I say that about so many plants that it can't possibly be true.

Haworthia limifolia, a close relative of H tessellata but lacking obvious windows in its leaves. It resembles opaque, molded plastic rather than translucent, carved wax.

The latin name tessellata comes from the tiled pattern in the leaf faces. Attractive, yes, but the bigger truth about these odd, waxy leaf faces is this: they evolved to be natural windows. Many Haworthia have adapted this way. Sunlight enters the plant body through these translucent windows and is converted into energy by many layers of chlorophyll-rich cells. This is especially useful in the arid climates where Haworthia tessellatamakes its living; the primary photosynthesis tissues are not exposed to the drying elements.

Haworthia tessellata 'Fang', a select clone named for the teeth and tubercles on the leaf undersides.

Leaves with window tops are described as fenestrate, from the Latin for window: fenestra.

Haworthia tessellata 'Super Tessellata', a beautiful, select clone

What's more, like many succulents, Haworthia tessellata can photosynthesize using Crassulacean Acid Metabolism (CAM). During CAM photosynthesis, the plant opens its stomata only during the cool of the night. It "inhales" in carbon dioxide and stores it in its thick, succulent tissues (while "exhaling" oxygen). During the heat of the day, the carbon dioxide stored deep in the plant can be used in photosynthesis because sunlight passes through the leaf windows, deep into the center of each leaf.

Haworthia tessellata in habitat. Photo by Jakub at http://haworthia-gasteria.blogspot.com/

See Also
Convergent Evolution in Succulent Desert Plants: Comparing Haworthia and Aloe (Africa) With Agave (America)