* 
Fre, 330. Two ASCI OF PEZIZA 
THE DICTIONARY OF GARDENING, 
Pyrenomycetes—continued. — 
in most, these groups of asci are surrounded with an 
outer coating of hyphæ, united so as to simulate true 
parenchyma. In one group—the Discomycetes—this pro- 
tecting tissue merely forms a saucer or disk, or a club, 
on which the asci stand (e.g.,in Peziza), and the surface 
bearing the asci is exposed. In a few, e.g., Ewoascus 
Pruni (see remarks on Funar, under Plum), the asci 
stand isolated and exposed, and not on any special area 
of the surface. In the Pyrenomycetes, including among 
them the Perisporacei, the protecting tissue forms a 
continuous sphere or flask-shaped perithecium, which 
entirely incloses the asci with the spores in them, and 
which, as in the Perisporiacew, may be entirely closed, but 
far more generally opens by a pore or slit on its upper 
surface, or at the end of a more or less elongated neck. 
As a rule, there are many asci in each perithecium ; but 
in a few species they may be few, or even reduced to 
a single ascus, as in Podosphera (see PLUM Funai). 
Both in Discomycetes and in simple Pyrenomycetes, the 
development of the asci and spores has been traced to 
a union of male and female organs, and the protecting 
layers have been traced to branches developed from the 
mycelium after the female cell is fertilised. 
STUMA, each with eight 
(magnified about 250 times). eight Spores 
The Pyrenomycetes live on every kind of food—on dead 
wood and leaves, on dead animal matter, on excrements, 
on the soil, and on living plants and animals; in this 
latter case, they are true parasites. 
hurtful to cultivated plants. An account of the more 
important structural characters of the Hrisyphew, and 
of the injuries they inflict, will be found under the 
headings and Oidium. The restricted, or 
true, Pyrenomycetes differ from the Perisporiacee (of 
which the Erisyphee form the section of most import- 
ance to gardeners) in the perithecium opening by a pore 
or a slit, and in the mycelium being not superficial, but 
sunk among the food, whether that is dead, or a living 
plant or animal, Hence, the mycelium is entirely con- 
eealed; and the parts which attract our notice are, 
in most cases, only the reproductive organs. There 
are several kinds of spores produced, as has been 
mentioned under Pleospora. The ascospores, or 
those contained in the asci, may be round, elliptical, 
or thread-like, transparent or brown, undivided, or 
divided by one, two, three, or many septa. In 
this latter case, the spores often seem very complex 
in their structure, being built up of many cells. The 
perithecia vary considerably in texture, whether nearly 
membranous, carbonaceous, or fleshy (Nectriacee), and in 
form of orifice, whether a simple slit (in Hysteriacei), or 
a pore (Pleospora), or with thickened lips (Lophiosto- 
macei). In some, the perithecia are scattered (Pleospora) ; 
in others, they are crowded together on specially modi- 
fied parts of the Fungus (in Xylaria, Claviceps, &e.), or 
are sunk in the mycelium, in a mass called a “stroma.” 
Besides the perithecia with ascospores, other structures, 
called pycnidia, much like perithecia in external appear- 
Some of them prove’ 
see Mildew and Oidium. Among the restricted Pyre- 
nomycetes, a good many species are parasitic upon 
Pyrenomycetes—continued 
ance, are developed; and in them are contained spores, 
often much like those contained in the asci, e.g., in 
Cucurbitaria Laburni, where both’ are multicellular and 
brown, but, perhaps, more often very different from them - 
in appearance, e.g., in Pleospora herbarum, in which the 
ascospores are multicellular and brown, and the pycnidio- 
spores are unicellular, transparent, and very much smaller 
(see Pleospora). The pycnidia have been named Phoma 
herbarum. Pyenidia are, in most cases, smaller and 
thinner-walled than the perithecia; but they vary in 
these respects, and also™in being solitary in some groups, 
and crowded together in others. Occasionally, they are 
sunk in a stroma. They usually occur on the mycelium 
before the perithecia are formed, but may be associated 
with the latter. In the pycnidia, the spores are pro- 
duced on the tips of branches, not in asci; but 
pycnidiospores are occasionally found in the same re- 
ceptacle with ascospores. 
Other modes of spore formation occur in many species: 
(see Pleospora), resulting in the formation of conidia on 
the tips of branches that rise from the mycelium creeping 
on the surface of the body in which the Fungus is 
growing. These conidiophores, or conidia-bearers, are 
very various in form and modes of branching, and in the 
structure and form of their spores. In some cases, they 
are so associated with the more perfect stages of the 
Fungi that there is little difficulty in recognising their 
relationships ; e.g., the very common T'ubercularia vulgaris 
on dead branches is always followed by Nectria cinna- 
barina in such a manner as to indicate clearly their 
being states of the same Fungus. But the greater 
number of conidiophorous Fungi have not yet been 
referred as earlier stages to higher forms, though careful 
observations will almost certainly result in their being 
so, and will free the study of microscopic Fungi from a 
vast amount of doubt, and from multitudes of so-called 
species. In the meantime, in the imperfect state of our 
knowledge of these plants, it is found expedient to 
retain them in the group called Hyphomycetes, even 
though they are thus associated with Peronospora, and 
with other forms not closely related to them. Still 
another mode of reproduction in some is by means of 
Sclerotia, or hard masses of mycelium (see Sclerotia). 
It has been necessary to enter thus fully upon the 
account of the modes of reproduction observed in the 
Pyrenomycetes, since it is these alone that afford 
material for distinguishing the various genera and 
species, the mycelium not yielding characters that can 
be relied on for genera, or even families, much less for 
species. For an account of the injuries inflicted on 
cultivated plants by thé Erisyphee among Perisporiacet, 
living plants; and several of these are injurious to field 
or to garden produce. Some of them are hurtful in the 
early stages of their growth, the perithecia being 
formed only after the death of the tissues on which 
they feed. Others only weaken the host-plants, and are 
to be found in all their stages upon living tissues of 
these plants. Some have already been referred to under 
the headings Pleospora and Plum (Funai). Among 
the most injurious forms may be mentioned one very 
hurtful to grasses that are grown for seed, viz., the 
Ergot (Claviceps purpurea), which, however, does so 
ree harm to gardeners as to require no special notice 
ere. 
PYRETHRUM (Pyrethron, the old Greek name used 
by Dioscorides, probably from pyr, fire; referring to the 
acrid roots of this genus). Feverfew. Orp. Composite. — 
A genus of mostly hardy, herbaceous perennials, now in- - 
cluded, by Bentham and Hooker, under Chrysanthemum. 
The distinctive features reside in the presence in Pyre- 
thrum of a pappus, in the form of an elevated membranous 
