The Linnaean Era j 371371 371
Paradise was surrounded by land, and plant species were free to spread across the globe via
seed dissemination. Linnaeus’s interpolation of geography into the Creation myth made a
nice just- so story, but, as he realized, it had neither biblical nor scientific support and was
thus not very compelling as an explanation for the fixity of species.
Searching for a more satisfying answer, Linnaeus began to consider the implications of
the sexual theory for the fixity of species concept, especially the phenomenon of hybrid-
ization. Exactly when Linnaeus first became aware of Fairchild’s Mule, the artificial
hybrid between carnation (Dianthus caryophyllus) and sweet William (Dianthus barba-
tus), is unknown. There is no record of any correspondence between the two men at the
Linnaean Society in London, and, at the time Fairchild died in 1729, Linnaeus would
only have been twenty- two.^62 In 1736, however, Linnaeus traveled to England and paid
visits to Sir Hans Sloane and Philip Miller. Presumably, both the sexual theory and plant
hybridization were prime topics of conversation. It seems likely that it was during this
visit that Linnaeus first became fully informed about Fairchild’s Mule and, possibly, the
work of Cotton Mather and others regarding hybridization in maize, for it was shortly
after this time that he began to incorporate hybridization into a revolutionary new theory
of the origin of species in which the number of species increased over time by a kind of
organic evolution.
The immediate catalyst for the new theory was the discovery by a student at Uppsala of an
unusual, toadflax- like plant growing on one of the islands of the Stockholm archipelago.^63 The
student pressed and glued the specimen to an herbarium sheet and brought it to Olof Celsius,
the renowned Uppsala professor of botany, who passed it on to Linnaeus. Linnaeus initially
confirmed the identification of toadflax (Linaria vulgaris), but upon closer inspection he real-
ized that the flowers of the inflorescence were so unusual that he began to suspect he was
the victim of a hoax. Had the student glued an inflorescence from a different plant onto the
herbarium sheet in an effort to deceive him and make him look ridiculous? He therefore pre-
vailed upon the student to bring him some living specimens and was able to confirm the pres-
ence of the aberrant flower structure on fresh material as well. Flowers of the genus Linaria
have bilaterally symmetrical corollas with four stamens and a single nectar spur. The bizarre
specimen found by the student, which Linnaeus named Peloria (Greek for “monstrous”), had
a radially symmetrical corolla with five stamens and five nectar spurs (Figure 13.2).
The taxonomic implications of Peloria were profound. If Peloria were found to breed true,
which it appeared to do, thus satisfying the definition of a species, it would overturn the fixity of
species doctrine. Even worse, Peloria, which had two pairs of stamens of unequal length, would
have to be placed in a different class from Linaria, which has five stamens of equal length.
This would completely demolish Linnaeus’s sexual system of classification because classes are
supposed to be widely separated from each other. In principle, no plant belonging to one class
should ever produce progeny belonging to another class. If species could transform willy- nilly
into different classes the result would be taxonomic bedlam, and there would be no possibility
of ever finding a natural classification system. In the words of Linnaeus:Nothing can, however, be more fantastic than that which has occurred, namely that
a malformed offspring of a plant which has previously always produced irregular
[bilateral] flowers now has produced regular [radial] ones. As a result of this, it does
not only deviate from its mother genus but also completely from the entire class and
thus is an example of something that is unparalleled in botany so that owing to the