Pharmaceutical botany - Lighthouse Survival Blog

62 PHARMACEUTICAL BOTANY
Order 5. Pyrenomycetales, the mildews and black fungi common as
superficial parasites on various parts of plants. To the black fungi
division of this order the Ergot fungus, Claviceps purpurea, belongs.
LiPE History or Claviceps Purpttrea
Through the agency of winds or insects the spores (ascospores or conidia) of this
organism are brought to the young ovaries of the rye (Secale cereale). They germinate
into long filaments called hyphas which, becoming entangled to form a myce-
lium, spread over the ovary, enter it superficially, secrete a ferment, and cause
decomposition of its tissue and the resultant formation of ayeUow-mucus substance
called honey-dew, which siurrounds chains of moniUform reproductive bodies known
as conidia. The honey-dew attracts certain insects which disseminate the disease
to other heads of grain.
The mycelial threads penetrate deeper and deeper into the ovary and soon form
a dense tissue which gradually consumes the entire substance of the ovary and hard-
ens into a purple somewhat curved body called a sclerotium, or ofi&cial ergot—the
resting stage of the fungus, Claviceps.
The ergot falls to the ground and in the following spring sprouts into several
stalked heads. Each (fruiting) head or ascocarp has imbedded in its surface numerous
flask-shaped invaginations called perithecia from the bases of which several
sacs or asci develop. Within each ascus are developed eight filiform spores (ascospores)
which, when the ascus ruptures, are discharged and are carried by the wind
to other fields of grain, there to begin over a new life cycle.
Class III. Basidiomycetes, or Basidia Fungi
This large class of fungi including the smuts, rusts, mushrooms,
gill and tooth fungi, etc., is characterized by the occurrence of a basidium
in the life history. A basidium is the swollen end of a hypha
consisting of one or four cells and giving rise to branches called sterig-
mata, each of which cuts off at its tip a spore.
Sub-class A. Protobasidiomycetes
(Basidium four-celled, each cell bearing a spore)
Order i. Ustilaginales, the smuts. Destructive parasites which
attack the flowers of various cereals, occasionally other parts of these
plants. Ex. : Ustilago M'aydis, the corn smut.
Order 2. Uredinales, the rusts. Ex.: Puccinia graminis, one of
the wheat rusts, living in the intercellular spaces of young wheat.