Glossary

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Term Definition
zoospore

Spore that forms within the sporangium and exits through the terminal pore and is capable of swimming for several hours. In Phytophthora, each zoospore has a tinsel flagellum and a whiplike flagellum.

wilt

Foliage becomes flaccid due to a water deficit. This is often the first aboveground symptom of root rot.

sympodium

A type of sporangiophore which appears simple, but where each successive sporangium develops on a branch behind and to one side of the previous apex, where growth has already ceased. (Pl. sympodia)

sporangium

A sac that bears endogenous, asexual spores. In Phytophthora, zoospores are produced in a sporangium. (Pl. sporangia)

sporangiophore

The hyphal strand on which the sporangium is formed; may be branched or unbranched to form compound or simple sympodia.

simple sympodium

An unbranched sympodium with a single sporangium produced externally from the base of the previous sporangium.

semi-papillate

Having papilla that are not well developed, shallow and less nipple-like than fully papillate structures.

reniform

Kidney shaped.

pyriform

Pear shaped, with the narrowest part at the base. Compare with obpyriform.

proliferation

Successive development of new sporangiophores; internal proliferation occurs when the sporangiophore continues to grow through the empty sporangium; external proliferation occurs from growth of a sporangiophore from beneath and external to a sporangium.

plerotic

to be full; e.g., a plerotic sporangium is one which is full of spores; a plerotic oospore is one that fills the oogonium. Compare with aplerotic.

persistent

Applied to structures that remain after their function has ceased; e.g., sporangia that remain in place after sporulation. Compare with caducous.

pedicel length

The length of pedicel on a sporangium after shedding by caducous species; three divisions are recognized by Gallegly and Hong: short, <5µm; intermediate, 5-20µm;and long, >20µm.

pedicel

A slender stalk or support of spores, sporangia, cystidia, asci, etc.

paragynous

Pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium. Compare with amphigynous.

papillate

Having a well developed papilla.

papilla

A small rounded or conic elevation, generally translucent, of the wall of sporangia and gametangia, which on breaking serves as the point of exit of zoospores.

ovoid

Egg-shaped; the widest part is at the bottom and the narrow part at the apex.

oospore

Zygote or thick-walled spore that forms within the oogonium after fertilization; may be long-lived.

oogonium

The female gametangium in which the oospore forms after fertilization by the antheridium. (Pl. oogonia)

obpyriform

Inversely pear-shaped, i.e. with the widest part at the point of attachment. Compare with pyriform.

obovoid

Inversely egg-shaped; ovoid, but with the widest part at the apex.

nested proliferation

A type of internal proliferation where the new sporangia develop successively inside the old sporangia.

mycelium

A mass of hyphae, often used to denote all hyphae comprising a thallus. (Pl. mycelia)

lesion

A localized area of diseased or damaged tissue.

lax sympodium

A sympodium in which the sporangiophores are long and loosely arranged. Compare with close sympodium.

internal proliferation

Internal proliferation occurs when the sporangiophore continues to grow through the empty sporangium.

intercalary

Positioned within a hypha, not terminally.

hyphal swelling

Globular swelling that forms at a branch point or within the mycelium. It is by definition (Blackwell 1949) not separated from the coenocytic mycelium by a septum. When separated by a septum and having a thickened inner wall, it is termed a chlamydospore.

hypha

Single, tubular filament of a fungal (or oomycete) thallus or mycelium; the basic structural unit of a fungus. (Pl. hyphae)

homothallic

Pertaining to sexual reproduction that can take place without the interaction of two different mating types.

heterothallic

Pertaining to sexual reproduction in which mating is possible only through interaction of different mating types.

globose

To have a rounded form resembling that of a sphere.

fusiform

Spindle-shaped; tapering at each end.

foliar

Pertaining to leaves.

flagellum

Whiplike or tinsel-like appendage of a zoospore that provides locomotion. (Pl. flagella)