Glossary - Westcott's Plant Disease - page 692

Glossary

Acervulus , pl. Acervuli . A “little heap,” an
erumpent, cushionlike mass of hyphae bearing
conidiophores and conidia, sometimes with
setae; characteristic of

Ascomycetes . One of the three main groups of the
fungi, bearing sexual spores in asci.
Ascospore . Produced in ascus by free cell
formation.
Ascus , pl. Asci . Saclike, usually clavate cell
containing ascospores, typically eight (Fig. 3,
p. 37).
Aseptate . Without cross-walls.
Asexual . Vegetative, having no sex organs or sex
spores; the imperfect stage of a fungus.
Autoecious . Completing life cycle on one host;
term used in rusts.
Bacteria . Microscopic one-celled organisms
increasing by fission.
Bactericide . Substance causing death of bacteria.
Basidiomycetes . Class 3 in the Fungi, character-
ized by septate mycelium, sometimes with
clamp-connections, and sexual

the Melanconiales

(Fig. 5, p. 43).
Acicular . Needlelike.
Aeciospore . Rust spore formed in an aecium.
Aecium , pl. Aecia . A cluster-cup, or cuplike
fruiting sorus in the rusts (Fig. 2, p. 349).
Aerobic . Living or active only in the presence of
oxygen.
Amoeboid . Not having a cell wall and changing in
form like an amoeba.
Allantoid . Sausage-shaped.
Alternate Host . One or other of the two unlike
hosts of a heteroecious rust.
Anamorph . State of life-cycle in which asexual
spores, or none, are produced.
Annulus . A ring; ringlike partial veil around stipe
in the mushrooms.
Antheridium , pl. Antheridia . Male sex organ in
the fungi.
Anthracnose . A disease with limited necrotic
lesions, caused by a fungus producing
nonsexual spores in acervuli (Fig. 1, p. 60).
Antibiotic . Damaging to life; especially a
substance produced by one microorganism to
destroy others.
Apothecium , pl. Apothecia . The cup-or saucer-
like ascus-bearing fruiting body; in the
Discomycete section of the Ascomycetes
(Fig. 3, p. 37; Fig. 9, p. 335).
Appressorium . A swelling on a fungus germ tube
for attachment to host in early stage of infection;
found especially in anthracnose fungi and rusts.
Ascocarp ,or Ascoma . Any structure producing
asci, as an apothecium, perithecium.

spores on

basidia (Fig. 4, p. 41).
Basidiospore . Spore produced on a basidium.
Basidium , pl. Basidia . Club-shaped structure,
which, after fusion of two nuclei, produces
four basidiospores (Fig. 4, p. 41).
Binucleate . Having two nuclei.
Blight . A disease with sudden, severe leaf
damage and often with general killing of
flowers and stems.
Blotch . A blot or spot, usually superficial.
Breaking , of a virus. Loss of flower color in
a variegated pattern, especially in tulips.
Canker . A lesion on a stem; a plant disease with
sharply limited necrosis of the cortical tissue
(Fig. 2, p. 155; Fig. 3, p. 161; Fig. 4, p. 165).
Carrier . Infected plant showing no marked symp-
toms but source of infection for other plants.
Catenulate . In chains, or in an end-to-end series.
Cerebroid . With brainlike convolutions or folds.