Fertilization by means of non-motile spermatia and a trichogyne are known among the Fungi in the families Collemaceae and Laboulbeniaceae.
Among the lower classes of plants we have scarcely any knowledge of Palaeozoic Bryophyta; Fungi were probably abundant, but their remains give us little information; while, even among the Algae, which are better represented, well characterized specimens are scanty.
Microscopic fungi are usually preserved in envelopes, or simply attached to sheets of paper or mounted as microscopic slides.
In the higher forms a storage and a mechanically-strengthening system may also be developed, and in some aerial Fungi an external protective tissue.
It is, however, among the Fungi that we find the most disastrous and elusive agents of disease.
Under the head of malformations we place cases of atrophy of parts or general dwarfing, due to starvation, the attacks of Fungi or minute insects, the presence of unsuitable food-materials and so on, as well as cases of transformation of stamens into petals, carpels into leaves, and so forth.
Of these the rust, smut and bunt fungi are by far the most common and the most destructive.
They are distinguished from the other fungi and the rest of the Basidiales by the great variety of the spores and the great elaboration of the life-history to be found in many cases.
Structural, having reference to the form and structure of the various parts, including (a) Morphology, the study of the general form of the organs and their development - this will be treated in a series of articles dealing with the great subdivisions of plants (see Angiosperms, Gymnosperms, Pteridophyta, Bryophyta, Algae, Lichens, Fungi and Bacteriology) and the more important organs (see Stem, Leaf, RooT, Flower, Fruit); (b) Anatomy, the study of internal structure, including minute anatomy or histology (see Plants: Anatomy).
Mechanical injury from without, and against the entry of smaller parasites, such as fungi and bacteria, but also and especially to prevent the evaporation of water from within.