some others, occasionally have their whole disk changed to ligulate white florets, destitute of stamens, and consequently abortive. Such are actually called double flowers in this Class, and very properly. Many exotic species so circumstanced are met with in gardens. A few very strange anomalies occur in this section, as already mentioned, p. 306, one Sigesbeckia having but 3 stamens, instead of 5, the otherwise universal number in the Class; and Tussilago hybrida, t. 430, as well as paradoxa of Retzius, having distinct anthers. Nature therefore, even in this most natural Class, is not quite without exceptions.
3. Polygamia frustranea. Florets of the disk, as in the preceding, perfect or united; those of the margin neuter, or destitute of pistils as well as of stamens ; only some
few genera having the rudiments of pistils in their radiant florets.
This Order is, still more evidently than the last, analogous to double flowers of other Classes. Accordingly, Coreopsis is the very same genus as Bidens, only furnished with unproductive radiant florets, C. bidens of Linnæus is the same species
