Xerophytes.Plants which grow in very dry soils; e.g., most hens, Ammophila (Psamma) arenaria, Elymus arenarius, Anasis aretioides, Zilla macro ptera, Sedum acre, Bupleurum spinosum, rtemisia herba-alba, Zollikofferia arborescens.
In some Australian acacias, and in some species of Oxalis and Bupleurum, the petiole is flattened in a vertical direction, the vascular bundles separating immediately after quitting the stem and running nearly parallel from base to apex.
Such whorled or verticillate bracts generally remain separate (polyphyllous), but may be united by cohesion (gamophyllous), as in many species of Bupleurum and in Lavatera.