prothallus


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Related to prothallus: sorus, indusium, homosporous

prothallus

a small thalloid structure produced by the germination of the spore in ferns and related plants, which bears the ARCHEGONIA and ANTHERIDIA and is the GAMETOPHYTE generation.
References in periodicals archive ?
Thallus corticolous, epiperidermal, up to 7 cm diam., continuous, white-grey, uneven, opaque; prothallus not observed.
The young prothallus of both species is distinctly lopsided, and the asymmetry often persists until maturity.
For sample from Control Station, the thallus is olive green and prothallus is bright white in colour.
Further studies on the prothallus, embryo, and young sporophyte of Tmesipteris.
This species is characterized by a usually conspicuous black prothallus and a diffusely areolate, dark grayish thallus.
This downward migration of the nucleus sets up an asymmetric first cell division, determining the developmental fate of the two daughter cells, one giving rise to the primary rhizoid, and the other giving rise to the prothallus. Thus, in dictating the direction of nuclear migration, gravity also dictates the developmental polarity of the spore.
The first stages of prothallus development lack mycorrhizal colonization even when rhizoids have developed (Fig.
The prothallus bears the female (archegonia) and male (antheridia) organs.
Form of mature prothallus: 0 = highly branched and vascularized; I = subterranean, elongate, and cylindrical; 2 = tuberous and subterranean; 3 = filamentous; 4 = branched and ribbon shaped; 5 = deeply lobed; 6 = cordate, may be branched; 7 = cordate, becoming ribbon like; 8 = highly reduced.