Species

90 Species

Although it was not published, this passage indicates, as Staeu notes, that Adanson
thought that it was resemblance for the observer that “made” species, and that varieties
were the subspecic changes that occurred in species. So he was a kind of taxonomic
essentialist; but was he a species xist? Adanson sought to answer the question whether
natural classication is meaningful if species change, which he believed they had done,
and that he had observed it. He cited both Linnaeus’ example of Peloria and J. Marchant’s
discovery in 1715 of a mutation in Mercurialis.^192 His own work with lettuce and basil
led him to conclude that varieties had become xed in each generation. Morton consid-
ers that Adanson in fact had a kind of genealogical approach to classication, given that
plants were mutable (he is the rst to use the term “mutation” in connection with taxo-
nomic transmutation). However, in 1769 he re-examined the question and concluded that
the changes he had observed before and since were neither due to hybridism nor did they
breed true, and so “the transmutation of species does not take place in plants, any more
than in animals.” Thus, he ended up a xist in practice, if not in principle.
Adanson’s natural method approach to classication was in one way quite stan-
dard. He focused on the shared characteristics for larger groups and distinguished
the smaller groups by their differences. Gareth Nelson notes

It is evident that Adanson acquired his notions of natural families not by study of his

articial systems, but by independent, and unspecied means ...:

“These diverse remarks, in showing the utility of botanical exploration [discovery of new

species in the tropics], explain why I became more and more convinced of the necessity to

consider plants in a totally new fashion. I believed it necessary to abandon old prejudice

in favor of [articial] systems, and the ideas on which the systems are based and which

limit our knowledge; and to search in nature herself for her system, if it is true that she

really has one. In this belief I examined all parts of plants, without exception, from the

roots to the embryo ... First I made a complete description of each plant species, consider-

ing each part in detail in a separate article; and to the extent that I encountered new spe-

cies with relations to species already described, I described the new species separately,

omitting the similarities and noting only their differences. It was by the ensemble of these

comparative descriptions that I perceived that the plants placed themselves naturally in

classes, or families, that could be neither articial nor arbitrary—not based on one or a

few parts that must vary within certain limits, but on all parts; such that the absence of

one part [in a given species] would be replaced and balanced by the addition of another

part that would restore the equilibrium.”^193

Jussieu: Species as Simples

Although he was mainly concerned with the nature of a natural system at much higher

levels of classication than the species level, Antoine-Laurent de Jussieu (1748–1836)

did also make some comments on species that indicate that at the time he published

his massive Genera plantarum secundum ordines naturalis disposita,^194 two distinct

approaches to species had developed. One was due to Ray, while the other was due

to Linnaeus, and Jussieu was more in line with Ray than Linnaeus.

(^192) Morton 1981, 309.
(^193) Nelson 1979.
(^194) Jussieu 1964.