This curious
discovery was described by Rudberg in his dissertation in the year 1744.
Soon afterwards other localities were discovered by Link near Gottingen
in Germany about 1791 and afterwards [467] in the vicinity of Berlin, as
stated by Ratzeburg, 1825. Many other localities have since been
indicated for it in Europe, and in my own country some have been noted
of late, as for instance near Zandvoort in 1874 and near Oldenzaal in
1896. In both these last named cases the peloric form arose
spontaneously in places which had often been visited by botanists before
the recorded appearance, and therefore, without any doubt, they must
have been produced directly and independently by the ordinary species
which grows in the locality. The same holds good for other occurrences
of it. In many instances the variety has been recorded to disappear
after a certain lapse of time, the original specimens dying out and no
new ones being produced. _Linaria_ is a perennial herb, multiplying
itself easily by buds growing on the roots, but even with this means of
propagation its duration seems to have definite limits.
There is one other important point arguing strongly for the independent
appearance of the peloric form in its several localities. It is the
difficulty of fertilization and the high degree of sterility, even if
artificially pollinated.
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