Crassulaceae consists of between 33 and 40 genera and more than 1700 species of succulent (water-retaining) plants. The family's idiosyncratic capacity to store water in its fleshy stems and leaves allows its species to live in otherwise inhospitably dry habitats and climate zones, from the frigid rockiness of alpine heights to the infernal heat of badlands and deserts. The plants are distributed throughout the world, but are most common north of the equator and in Africa.

About 30 species of Sempervivum grow in tightly swirling rosettes from among the rocks and gravel that form a low, greenhouse-supporting wall in our E.H. Lohbrunner Alpine Garden. Each plant is carefully marked, as the plants' propensity to naturally hybridize renders identification notoriously difficult. The genus name derives from the Latin for 'always living', which nicely figures the persistence with which Sempervivum species confront even the most hostile and trying of environmental episodes, among them drought and heavy frost. The plants take several years to put forth their star-shaped flowers, and they die once these blooms have fallen; careful, committed gardeners need not fret, however, for the passing plants bestow a good number of viable offsets upon the gardens of future years. In general, Sempervivum species grow without difficulty when sited in well-drained sandy soils and exposed to either full sun or partial shade. The genus has a particularly rich symbolic history, and its putative sacredness to the lightning-hurling deity of Roman mythology, Jove, seems to have inspired the superstitious postulate that the plant, when grown on a roof, protects the house below from the surging skies of electrical storms.

Our Sempervivum 'Othello', which has formed a uniquely large colony on the greenhouse wall, is here dressed with many small hairs that are gently bathed with rainwater. The plant's numerous and variegated rosettes seem to spin like a collection of old tops, though the plant of course remains still and firmly rooted in the ground below. For me, this cannot help but engender thoughts of both the dizzying intensity and the all-encompassing, if misguided, rage of the tragic character from whom the cultivar derives its name.