In that case either very little secondary tissue is formed, as in the gourds, some Ranunculaceae, &c., or a considerable amount may be produced (clematis, barberry, ivy).
(3) Into the alpine region (6200 to 10,400 ft.) penetrate a few very stunted oaks (Quercus subalpina), the junipers already mentioned and a barberry (Berberis cretica), which sometimes spreads into close thickets.
In some leaves, as in the barberry, the veins are hardened, producing spines without any parenchyma.
The leaves of barberry and of some species of Astragalus, and the stipules of the false acacia (Robinia) are spiny.
We have wild olive, species of rock-rose, wild privet, acacias and mimosas, barberry and Zizyphus; and in the eastern ramifications of the chain, Chamaerops humilis (which is applied to a variety of useful purposes), Bignonia or trumpet flower, sissu, Salvadora persica, verbena, acanthus, varieties of Gesnerae.
In due time the fungus, known as Aecidium Berberidis, appears on the barberry leaves in the form of small cluster-cups on aecidia, each of which is filled with chains of orange-coloured aecidiospores.