The generic name was proposed by Vaillant in 1719[438], and adopted by Linnaeus, who classed the Stoneworts with aquatic phanerogams. As long ago as 1623[439] a figure of Chara was published by Caspar Bauhin as a form of Equisetum. The generic name Chara has usually been applied to recent and fossil species alike. The existing species have a wide distribution; Chara foetida, A. Br., a common British form, occurs in practically all parts of the world. Stems and calcareous ‘fruit-cases’ occur fairly commonly in a fossil state, and differ but little from recent species, at least as regards essential features.
It is difficult to say at what geological horizon the Stoneworts are first represented. The first certain traces of Chara occur in Jurassic rocks, but certain spirally marked subspherical bodies have been recorded from Devonian and Carboniferous strata, which closely resemble Chara oogonia, and may be Palaeozoic representatives of the genus.
In 1889 Mr Knowlton[440] of the American Geological Survey described some ‘problematic organisms’ found in Devonian rocks at the falls of the Ohio. Examples of these fossils are shown in fig. 46 b and c; the spirally grooved body measures from 1·50 to 1·80 mm. in diameter, and about 1·70 mm. in length. The Chara-like character of the fossils had been previously suggested by Meek[441] in 1873. Without going into the arguments for or against placing these fossils in the Chareae, they may at least be mentioned as possible but not certain Palaeozoic forms of Chara or an allied genus.
Fig. 46. a. Chara Bleicheri Sap. × 30. b and c. Devonian Chara? sp. circa × 12. d and e. Chara Wrighti Forbes. circa × 12.
1. Chara Bleicheri, Saporta. Fig. 46, a.
In this form the ‘fruits’ are minute and subspherical, ·39-·44 mm. long, and ·35-·40 mm. broad, showing in side view 5–6 slightly oblique spiral bands. Each spiral band bears a row of slightly projecting tubercles.
This species was first described by Saporta[442] from the Oxfordian (Jurassic) rocks of the Department of Lot in France; it is compared by the author of the species with Chara Jaccardi Heer, described by Heer from the Upper Jurassic rocks of Switzerland.
2. C. Knowltoni, Seward. Fig. 45, a and b, and Fig. 47.
The Oogonia are broadly oval, about ·5mm. in length, and at the broadest part of about the same breadth. The surface is marked by eleven or twelve bands in the form of a flattened spiral. The stems possess investing cortical cells.