Part 26

The perithecia are always embedded in a black stroma, and are not distinctly separated from it. The accessory forms of reproduction are: conidiophores, conidiocarps, and yeast-like conidia. The majority are parasites. One order.

Order =Dothideaceæ=. Phyllachora graminis produces scab-like patches on the leaves of the Grasses.--Scirrhia rimosa grows on the leaf-sheathes of Phragmites.--Rhopographus pteridis on Pteridium aquilinum.

Family 4. =Hysteriales.=

This family, like the following, has hemiangiocarpic ascocarps (apothecia). These are closed in the early stages, but when ripe open in a valvular manner by a longitudinal fissure; they are black, oblong, and often twisted. Some species are parasites, especially upon the Coniferæ.

Order 1. =Hysteriaceæ.= Hysterium pulicare upon the ruptured bark of many trees.

Order 2. =Hypodermaceæ.= The species of Lophodermium live upon the leaves of Conifers, and are the cause of their falling off (blight). L. pinastri (Fig. 125), on the leaves of Pinus and Picea; the leaves become red-brown and fall off; at first conidiocarps are formed, and later apothecia; L. nervisequium (Fig. 123), on Abies alba; L. macrosporum (Fig. 124), on Picea excelsa; L. brachysporum, on Pinus strobus.

Order 3. =Dichænaceæ.=

Order 4. =Acrospermaceæ.=

Family 5. =Discomycetes.=

The ascocarps (apothecia) are at first closed, and only open at the time of their ripening, not valvularly, but more or less like a saucer or cup, so that the hymenium lies exposed on their upper surface. In the first three sub-families, and generally also in the fourth, the apothecia are formed inside the substratum. The apothecia are, in contrast to the Pyrenomycetes, light and brightly coloured, and their size varies very much, and may be several centimetres in diameter. Paraphyses are often present between the asci; they often contain colouring matter, and give to the disc its characteristic colour. The tissue on which the asci are borne is known as the hypothecium. The shape and colour of the spores is not so varied as in the Pyrenomycetes. The accessory forms of reproduction are conidia (sometimes of two forms), chlamydospores, and oidia. The family is divided into 5 sub-families.

Sub-Family 1. =Phacidiales.=

The apothecia are developed in the interior of the substratum, which they break through, and in general dehisce apically. The envelope is tough and black. Hypothecium inconspicuous; hymenium flat.

Order 1. =Euphacidiaceæ.= Phacidium abietinum, on the leaves of Abies alba.--Rhytisma; the pycnidia are found in the summer on the green leaves, while the apothecia are developed on the fallen leaves and dehisce in the following spring. R. acerinum causes black spots on the leaves of the Sycamore, and R. salicinum on Willows.

Order 2. =Pseudophacidiaceæ.=

Sub-Family 2. =Stictidales.=

The apothecia when ripe break through the substratum which forms a border round them. Hymenium generally saucer-shaped.

Order 1. =Stictidaceæ.= Stictis.

Order 2. =Ostropaceæ.= Ostropa.

Sub-Family 3. =Tryblidiales.=

The apothecia are embedded in the substratum in the early stages, and then are raised high above it. Hypothecium thick. Hymenium cup-shaped.

Order 1. =Tryblidiaceæ.= Tryblidium.

Order 2. =Heterosphæriaceæ.= Heterosphæria patella on the dead stalks of Umbellifers.

Sub-Family 4. =Dermateales.=

The apothecia in the early stages are embedded in the substratum and then break through it, or are from the first situated on the surface of the substratum. Hypothecium thick.

Order 1. =Cenangiaceæ.= Cenangium.

Order 2. =Dermateaceæ.= Dermatea.

Order 3. =Patellariaceæ.= Patellea, Biatorella, Patellaria.

Order 4. =Caliciaceæ.= Calicium, Coniocybe, etc., on the bark of trees.