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Term Definition

A localized area of diseased or damaged tissue.


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

nested proliferation

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


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


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


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


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


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


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.


Having a well developed papilla.


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


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

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.


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


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.


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.


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


Kidney shaped.


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

simple sympodium

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


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


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


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)


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


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.