580 
Praia.—A Review of the Genera 
Historical Review of Micrococca. 
The section Micrococca , as understood by Mueller, is monotypic and 
corresponds with Bentham’s genus of the same name. This genus Micro¬ 
cocca was established by Bentham in 1849 (Hook., Niger Flor., 503) to 
accommodate the tropical weed of cultivated ground, widely spread in 
the Eastern Hemisphere, which supplies Baillon with a title for the paper 
alluded to in our opening paragraphs. 1 This plant is so strikingly like 
Mercurialis perennis , Linn., that in certain states, were its flowers not 
examined, it might, as Mueller points out (DC. Prodr., xv. 2, 790), be easily 
mistaken for that species. As early as 1692 Plukenet did indeed treat it 
(Phytogr., t. 205, fig. 4) as a species of Mercurialis ; M. maderaspatensis 
tricoccos acetabulis destituta. Linnaeus chose not to accept this position for 
the plant, but referred it to Tragia , in 1747 (Flor. Zeyl., 334) as T. foliis 
ovatis, and again in 1753 (Sp. PL, 980) as T. Mercurialis. This treatment 
is, however, less satisfactory than that of Plukenet, to which Lamarck 
independently reverted when, in 179 6 (Encyc. Meth., iv. 120), he described 
the plant as Mercurialis alternifolia. But Lamarck’s view, though more 
natural than that of Linnaeus, was not adopted by subsequent authors, 
and the Linnaean treatment was followed until 1849, when Bentham solved 
the difficulty by treating Tragia Mercurialis , Linn. (. Mercurialis alternifolia , 
Lamk.), as the type of a distinct genus. But Bentham’s proposal, though 
much more satisfactory than those of Linnaeus and Lamarck, has not been 
generally accepted ; twelve years later Dalzell and Gibson (Bomb. Flor., 227), 
Thwaites (Enum. PI. Zeyl., 271), and Baillon (Adansonia, iii. 167) inde¬ 
pendently and simultaneously refused to adopt it. In each of these works 
a different conclusion was arrived at. Dalzell and Gibson, in 1861, while 
recognizing that the plant in question is not a Tragia when that genus 
is restricted to its natural limits, were influenced by Linnaeus’s arrangement 
to such an extent as to believe that it was nevertheless congeneric with 
Tragia Chamelaea , Linn. (Sp. PL, 981), a plant which had been shown by 
A. de Jussieu (Tent. Gen. Euphorb., 39), in 3824, to be a member of another 
genus, Micros tackys, A. Juss. The transfer of Micrococca Mercurialis , 
Benth., to this genus Micr os tacky s, suggested in the Bombay Flora, is there¬ 
fore no great improvement on the Linnaean arrangement. This criticism 
1 It would appear that in 1858 Baillon was of opinion that Micrococca Mercurialis , Benth., 
differed from Mercurialis alternifolia , Lamk. : in his Etude generate, p. 436, he accepted Micrococca 
as defined by Bentham, while in the same work, p. 490, he treated Mercurialis alternifolia as the 
basis of a new section ( Erythranthe , Baill.) of Mercurialis. But Baillon’s Micrococca is not the 
same as Bentham’s; it is made to include Mercurialis tricocca, E. Mey., which is in reality 
the basis of the distinct genus Leidesia, Muell. arg. (DC. Prodr., xv. 2, 792). In 1862, however, 
Baillon had become satisfied as to the identity of Mercurialis alternifolia with Micrococca 
Mercurialis and had become aware that Mercurialis tricocca is quite distinct. This last species he 
now referred to his own genus Seidelia , which he, as already explained, also now treated as a section 
of Mercurialis , at the same time merging his own Mercurialis § Erythranthe of 1858 in Mercurialis 
§ Trismcgista. 
