In the mountains of Peru we find such characteristic northern genera as Draba, Alchemilla, Saxifraga, Valeriana, Gentiana and Bartsia.
Taking, however, the Andean flora as typical, it contains a very marked endemic element; Ball finds that half the genera and four-fifths of the species are limited to it; on the other hand, that half the species of Gamopetalae belong to cosmopolitan genera such as Valeriana, Gentiana, Bartsia and Gnaphalium.
The limb of the calyx may appear as a rim, as in some Umbelliferae; or as pappus, in Compositae and Valeriana.
In Valeriana the superior calyx is at first an obsolete rim, but as the fruit ripens it is shown to consist of hairs rolled inwards, which expand so as to waft the fruit.
In Valeriana, Antirrhinum and Corydalis, the spur is very short, and the corolla or petal is said to be gibbous, or saccate, at the base.