Linnaeus’s binomial system was almost at once adopted by the whole botanical world and the discovery and tabulation of lichens as well as of other plants proceeded apace. Scopoli’s[66] _Flora Carniolica_, for instance, published in 1760, still adhered to the old descriptive method of nomenclature, but a second edition, issued twelve years later, is based on the new system: it includes 54 lichen species.
About this time Adanson[67] proposed a new classification of plants, dividing them into families, and these again into sections and genera. He transferred the lichens to the Family “Fungi,” and one of his sections contains a number of lichen genera, the names of these being culled from previous workers, Dillenius, Hill, etc. A few new ones are added by himself, and one of them, _Graphis_, still ranks as a good genus.
In England, Hudson[68], who was an apothecary and became sub-librarian of the British Museum, followed Linnaeus both in the first and later editions of the _Flora Anglica_. He records 102 lichen species. Withering[69] was also engaged, about this time, in compiling his _Arrangement of Plants_. He translated Linnaeus’s term “Algae” into the English word “Thongs,” the lichens being designated as “Cupthongs.” In later editions, he simply classifies lichens as such. Lightfoot[70], whose descriptive and economic notes are full of interest, records 103 lichens in the _Flora Scotica_, and Dickson[71] shortly after published a number of species from Scotland, some of them hitherto undescribed. Dickson was a nurseryman who settled in London, and his avocations kept him in touch with plant-lovers and with travellers in many lands.
The inevitable next advance was made by Weber[72] who at the time was a Professor at Kiel. In a first work dealing with lichens he had followed Linnaeus; then he published a new method of classification in which the lichens are considered as an independent Order of Cryptogamia, and that Order, called “Aspidoferae,” he subdivided into genera. His ideas had been partly anticipated by Hill and by Adanson, but the work of Weber indicates a more correct view of the nature of lichens. He established eight fairly well-marked genera, viz. _Verrucaria_, _Tubercularia_, _Sphaerocephalum_ and _Placodium_, which were based on fruit-characters, the thallus being crustaceous and rather insignificant, and a second group _Lichen_, _Collema_, _Cladonia_ and _Usnea_, in which the thallus ranked first in importance. Though Weber’s scheme was published in 1780, it did not at first secure much attention. The great authority of Linnaeus dominated so strongly the botany of the period that for a long time no change was welcomed or even tolerated.
