Page:Popular Science Monthly Volume 53.djvu/786

762 of the Coliseum of Rome, consists conspicuously of fleshy-leaved Sempervivums and Senecios, whose roots penetrate the tiles of the houses and the stones of the streets. It is curious how many of these fleshy plants have their leaves growing in rosettes, producing a similarity



between the members of widely separated orders (e. g., Euphorbia balsamifera, Sonchus Kleinia, species of Sempervivum, Senecio, and Statice). Is this also a means for the reduction of transpiration?

The same question (this time as regards the flowers) applies to the species whose blossoms close soon after noon. The volcanic wastes, brilliant in the morning with the bright flowers of Helianthemum, Fagonia, Calendula, Sonchus, and Anagallis, are in the afternoon like a house where the lights are gone out, for all the blossoms have gone to sleep, and there is nothing in sight but brown soil and dull-green leaves.

The curious plants with twiglike leaves seem also to have been provided against too great loss by transpiration. Such are Plocama, a strange rubiaceous shrub which looks like a diminutive weeping willow; Genista rhodorhizoides, called by the insulars "retama," whose flowers appear even in the dry season, and, in the time of rain, whiten the hills; Spartium junceum, an even more perennial bloomer, with brilliant yellow blossoms brightening dusty waysides;