[Dunnington (1878)] detected manganese in the ash of wheat, ·00144 gm. (as Mn3O4?) in 300 grams of “Dark Lancaster” variety, equivalent to ·027% of the pure ash. The ash was exhausted with nitric acid, and after separating the iron the ammonium sulphide precipitate was found to contain manganese, and gave by fusion with nitre and sodium phosphate a violet coloured mass. [Andreasch (1878)] found slight traces of Mn3O4 in the flowers of Dianthus caryophyllus, none occurring elsewhere, while in Rosa remontana it appeared in both leaves and flowers.
[Maumené (1884)] tested many food plants and concluded that some quantity of manganese is frequently present in potato, rice, barley, carrot, lentil, pea, beetroot, asparagus, chicory, most fruits, tea, and also in some fodder plants, as lucerne, oats, and sainfoin. [Ricciardi (1889)], [Hattensaur (1891)] also added to the list of plants proved to contain manganese. [Guerin (1897)] studied the manganese content of woody tissues. Sawdust was treated with distilled water containing 1% caustic potash, expressed, and filtered after two or three days. A brown coloured liquid was obtained, which when treated with a slight excess of hydrochloric acid gave an abundant flocculent precipitate. This precipitate proved to be soluble in pure water, so it was washed with slightly acidulated distilled water, and after further purification was analysed. No trace of iron was obtained, but about ·402% Mn was found. Guerin regarded the precipitate as a “nucleinic” combination, which he supposed to occur generally in wood and to contain the manganese present in the woody tissues of all plants.
[Schlagdenhauffen and Reeb (1904)] detected manganese in a petrol extract of such cereals as barley, oats, and maize, and since inorganic salts of manganese are not soluble in such liquids as ether or petrol they concluded that the manganese must be present in the plant in organic combination, thereby upholding Guerin’s view. [Loew and Seiroku Honda (1904)] give a table of Mn3O4 in the ashes of certain trees. This is very high in some cases, rising to 11·25% in the ash of beech leaves, 6·73% in birch leaves, and 5·48% in chestnut fruits.
[Gössl (1905)] gives lists of the distribution of manganese in plants, both Thallophytes and Phanerogams, indicating the presence of much or little of the element. As a rule, he states, marsh and water plants gather up more manganese than do land plants.
The Gymnosperms seem to be particularly rich in their manganese content. [Schröder (1878)] tested for the element in firs and pines and found the following amounts of Mn3O4.
| In 100 parts ash. | In 1000 parts dry matter. | ||||
| Fir | Pine | Fir | Pine | ||
| 33·18 | 13·46 | 2·76 | ·77 | ||
He gave a table of detailed analyses showing the differing proportions of manganese in the different parts of the fir.
[Baker and Smith (1910)] paid special attention to manganese in their exhaustive work on the Pines of Australia. They state that “in the anatomical investigations of the timber, bark, and leaves of the various species, there was found to be present, in a more or less degree, a naturally brownish-bronze coloured substance, which invariably stained dark brown or almost black with haematoxylin.” This substance on careful investigation proved to be a compound of manganese. The quantity present varies with the species and also with the plant organs. The different species of the genus Callitris show variable percentages of manganese from a maximum of 0·230% in C. gracilis, to a minimum of 0·010% in C. robusta. The percentage of manganese in Australian Coniferae other than Callitris is given by the authors in the following table:
| Ash of timber of | Agathis robusta | 0·145% | Mn. | |||
| „ | „ | Araucaria Cunninghamii | 0·054% | „ | ||
| „ | „ | Araucaria Bidwilli | 0·077% | „ | ||
| „ | „ | Actinostrobus pyramidalis | 0·077% | „ | ||
| „ | „ | Podocarpus elata | 0·002% | „ | ||
| „ | „ | Dacrydium Franklini | 0·129% | „ | ||
| „ | „ | Athrotaxis selaginoides | 0·019% | „ | ||
| „ | „ | Phyllocladus rhomboidalis | 0·145% | „ | ||
| Air-dried | black gum of | Agathis robusta | 0·0046% | „ | ||
| „ | „ | Araucaria Cunninghamii | 0·0038% | „ | ||
Baker and Smith assume that manganese is essential to the production of the most complete growth of Coniferae. The element is found in these plants even when they grow on soils containing only traces of manganese and it is suggested that possibly the excess or deficiency of manganese in the soil helps to govern the location of certain of the Australian Coniferae. The authors conclude that manganese may be essential to the growth of these plants, and that its association with plant life may be considered to date back to past geological time, as is indicated by plates illustrating fossil woods.