A photo of Claude Jordan.
https://www.amazon.com/lorigine-Diverses-Vari%C3%A9t%C3%A9s-Fruitiers-G%C3%A9n%C3%A9ralement/dp/B002JVXGEU/?tag=2022091-20
1853
Claude Jordan was born on October 29, 1814, in Lyons, France. He belonged to one of the most distinguished families of the Lyons bourgeoisie. His father, César, was a rich merchant; his mother, Jeanne-Marie (called Adèle) Caquet d’Avaize, was the daughter of a lawyer. Camille Jordan, the writer, and politician was his uncle, and the mathematician Camille Jordan was a cousin.
Jordan received his secondary education there and, renouncing a career in commerce, turned to the natural sciences. He frequented a group of cultivated amateurs who enlivened the Linnaean Society of Lyons, and he soon specialized in botany under the direction of Nicolas Seringe, a military surgeon who became director of the Lyons Botanical Garden and whose assistant he was for a time.
Jordan’s task originally was purely descriptive and modest: to complete or correct the existing French floras on certain points. Between 1836 and 1846 he was essentially an observer and a researcher in the field. Each year he made several long botanical journeys, usually beyond the southeast but rarely outside of France (except to Corsica and Italy). These trips and the samples sent him by the many botanists with whom he corresponded allowed Jordan to assemble one of the most important private herbaria in Europe. His personal fortune enabled him to amass a library and experimental equipment comparable with those of the great professional botanists of his time.
Between the ages of twenty-five and thirty, Jordan concentrated on certain plants difficult to classify that had been brought to his attention by his friend Marc-Antoine Timeroy. These plants did not coincide exactly with the descriptions of the floras, and yet they could not be treated as simple varieties. Jordan soon became convinced, on these grounds, that the classic method of description itself was too schematic: a single species name was almost always applied to a multiplicity of forms that were quite similar, yet distinct and stable. This was particularly the explanation of the so-called polymorphous species, to which the very special faculty of “varying” was attributed. As early as 1846 Jordan concluded that at least five “easy to distinguish although very closely related” species are designated by the name Viola tricolor L. (the pansy); each of them, moreover, proves to be invariable after several years of cultivation.
Jordan announced these general conclusions in 1846 and 1847 to the Linnaean Society of Lyons in a series of seven monographs entitled Observations sur plusieurs plantes nouvelles rares ou critiques. From then on, the concept of species itself was in question. Beginning in the 1850s, Jordan became a theoretician and virtually chef d'école. The Linnaean notion of species corresponded, according to him, not to the real boundaries of the plant forms but to a crude division suggested by simple, practical convenience: it retained only those characteristics that are easily distinguished with the naked eye by a botanist of average experience and that are preserved when the plant is dried in a herbarium.
Experiment shows that a great many essential traits are not necessarily of this sort. Furthermore, the rigorous invariability of the species, largely underestimated by classical botanists, is confirmed by the facts and is already contained in the pure concept of species in general, which is logically prior to experiment and is the basis on which experiment can be methodically conducted and interpreted. The living species was a being of this kind: its “substantial” character was confirmed by its permanence during the course of generations, and every type that showed itself to be variable in its lineage was hybrid. Varieties, properly speaking, originate among the plants from superficial, environmentally determined modifications, which are not transmitted to the descendants; they do not affect the “substance” of the species.
This break with traditional concepts necessitated a change in method. “Closely related” species (espèces affines) exist everywhere; a given species, Jordan noted, was almost always surrounded, in a single location, by several analogous forms. All the true species could be counted only by controlling the descendants, that is, by cultural experimentation. Giving up his botanical expeditions, Jordan now limited his activity as an investigator to his experimental garden; the first one measured only about 400 square meters. About 1850 an inheritance from an uncle enabled him to buy a plot at Villeurbanne that he gradually increased to 12,000 square meters. At its best, it had about 400 flower beds, grouped in equal squares and containing approximately 50,00060,000 plants. A series of related forms belonging to the same Linnaean species was placed in the same flower bed, and their complete stability from year to year was verified. Thus, twenty-five kinds of Scabiosa succisa, thirty-five of Sempervivum tectorum, and so on, coexisted without ever intermingling.
The record was established by Draba verna (a crucifer with rosette leaves and small flowers that is frequently found in spring on walls and embankments), from which as many as 200 distinct forms were obtained. These “genuine species” were distinguished not by a major difference limited to one characteristic (Jordan considered the sudden modifications that sometimes disturb a characteristic in a line to be an accident, a lusns naturae that may be disregarded) but rather by a series of small but very stable details: for example, by bifurcated or trifurcated hairs, petals that are more or less narrow, fruits varying in size in relation to the length of the stem, and so on.
Yet if true species are rigorously invariable, how can one interpret the effects of cultivation, which seems to create and determine the quantity of new forms? In reply to this question, Jordan published De l'origine des diverses variétés ou espèces (1853). In fields, gardens, and orchards, he explains, many plants may be seen that were unknown, say, in the seventeenth century. But either they are purely individual variations due to the environment - and it is the permanence of this environment, not heredity, that creates the uniformity of the successive generations - or else it is a question of true species; but then they are new only for us, since they already existed in earlier times.
Jordan's career ended in growing isolation. In 1864 he entrusted the management of his garden to Jules Fourreau. Some deplored the influence that Fourreau immediately began to exert on him: he was more Jordanian than his master. He incited Jordan, it was said, to multiply species without limit by arbitrarily purging his flower beds in order to make the lines more homogeneous, sometimes dispensing with the cultural criterion in the process. Jordan maintained this orientation after Fourreau’s death. The last years of this obstinate monarchist saw his involvement in a naïve political enterprise that estranged a great many of his former friends.
Claude Jordan went down in history as a noted botanist and taxonomist, famous for devising and using a particularly narrow species concept, and for naming 1,685 species. He also created one of the largest herbariums known to exist, as he acquired exsiccatae series from around 200 other botanists.
In 1849 the plant genus Jordania was named in his honor by Pierre Edmond Boissier and Theodor von Heldreich. He also has several species named after him; Rosa jordani and Viola jordani being a couple of examples.
Jordan was born and raised in a Catholic family.
Jordan was a Royalist.
Jordan was a member of the Société Botanique de France, the Imperial Society of Naturalists of Moscow, the Royal Botanical Society of Belgium, and many others.
Jordan never maried.
