Plectenchyma

a false tissue formed in lower plants by the matting of multicellular hyphae (in fungi) or filaments (in algae). The hyphae and filaments of plectenchyma consist of cells that divide only by transverse septa. This is in contrast to true tissue, in which the cells divide in all directions. The degree of matting determines whether the plectenchyma is loose (in some algae, hymenomycetes, and the “pith” of lichens) or compact (in the sclerotia of fungi, in the “bark” of lichens).