The practical experiments of horticulturists, though not made with scientific precision, deserve some notice.

It is notorious in how complicated a manner the species of Pelargonium, Fuchsia, Calceolaria, Petunia, Rhododendron, etc.

, have been crossed, yet many of these hybrids seed freely.

For instance, Herbert asserts that a hybrid from Calceolaria integrifolia and plantaginea, species most widely dissimilar in general habit, "reproduces itself as perfectly as if it had been a natural species from the mountains of Chile.