AMADOU, a soft tough substance used as tinder, derived from Polyporus fomentarius, a fungus belonging to the group Basidiomycetes and somewhat resembling a mushroom in manner of growth.
Since about 1880 our knowledge of the species which can enter into such relationships has been materially extended, and the fungal constituents of the Lichens are known to include Basidiomycetes as well as Ascomycetes.
In the two genera of lichens - the Basidiolichens - i n which the fungus is a member of the Basidiomycetes, we have the fructification characteristic of that class of fungi: these are dealt with separately.
For some obscure reason the Basidiomycetes do not readily form lichens, so that only a few forms are known in which the fungal element is a member of this family.
In many Basidiomycetes minute branches arise below the septa; their tips curve over the outside of the latter, and fuse with the cell above just beyond it, forming a clamp-connexion.
Uredospores, septa of Basidiomycetes), spirals, reticulations, rings, &c. (capillitium fibres of Podaxon, Calostoma, Battarrea), occur as in the vessels of higher plants, while sculptured networks, pittings and so forth are as common on fungus-spores as they are on pollen grains.
It has been accepted for some time now that the majority of the fungi proper fall into three main groups, the Phycomycetes, Ascomycetes and Basidiomycetes, the Schizomycetes and Myxomycetes (Mycetozoa) being considered as independent groups not coming under the true fungi.
The scheme of Brefeld, which was based on the view that the Ascomycetes and Basidiomycetes were completely asexual and that these two groups had been derived from one division (Zygomycetes) of the Phycomycetes, has been very widely accepted.
It is also possible in the absence of satisfactory intermediate forms that the Ascomycetes and Basidiomycetes have also been derived from the algae independently of the Phycomycetes, and perhaps of one another.
On this basis, with other interesting morphological comparisons, Brefeld erected his hypothesis, now untenable, that the Ascomycetes and Basidiomycetes diverge from the Zygomycetes, the former having particularly specialized the ascus (sporangial) mode of reproduction, the latter having specialized the conidial (indehiscent one-spored sporangiole) mode.
Brefeld regarded the promycelium as a kind of basidium, bearing lateral or terminal conidia (comparable to basidiospores), but since the number of basidiospores is not fixed, and the basidium has not yet assumed very definite morphological characters, Brefeld termed the group Hemibasidii, and regarded them as a halfway stage in the evolution of the true Basidiomycetes from Ph co Y Y mycetes, the Tilletia type leading to the true basidium (Autobasidium), the Ustilago type to the proto pm basidium, with lateral spores; but this p m view is based on very poor evidence, so that it is best to place these forms?p, c;,::, as a separate group, the Ustilaginales.
Mucor, Exoasci, Ustilagineae, higher Ascomycetes and Basidiomycetes); and (2) the question as to the physiological nature and meaning of fermentation.
This group like the rest of the Basidiales exhibits an association of nuclei at some point in its life-history, but unlike the case of the Basidiomycetes the point of association in the Uredineae is very well defined in all those forms which st .:_ possess aecidiospores.
Although the Uredineae clearly lead on to the Basidiomycetes, yet owing to their retaining in many cases definite traces of sexual organs they are clearly a more primitive group. Their marked parasitic habit also separates them off, so that they are best included with the Basidiomycetes in a larger cohort which may be called Basidiales.
Most of Basidiomycetes are characterized by the large sporophore on which the basidia with its basidiospores are borne.
It must be clearly borne in mind that though the Basidiomycetes show no traces of differ entiated sexual organs yet, like the micro and lepto forms of the Uredineae, they still show (in the association of nuclei and later fusion of From Annals of Botany, by permission of the Clarendon Press.
Basidiomycetes: Dangeard, "La Reprod.
Sexuelle des Basidiomycetes," Le Botaniste (1894 and 1900); Maire, "Recherches cytologiques et taxonomiques sur les Basidiomycetes," Annexe du Bull.
Aus den Tropen, Heft 8 (Jena, 1895) Nichols, "The Nature and Origin of the Binucleated Cells in certain Basidiomycetes," Trans.
This, by far the smaller division of Basidiomycetes, includes those forms which have a septate basidium.
In this by far the larger division of the Basidiomycetes the basidia are undivided and the four basidiospores are borne on short sterigmata nearly always at the apex of the basidium.