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Thallus (pl.: thalli), from Latinized Greek θαλλός (thallos), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria.
The vegetative structure of Conocephalum is a thallus which has the appearance of a flattened body of plant tissue. [5] [22] The thallus is irregularly branched [4] and relatively large, reaching lengths of roughly 20-24 cm. [4] [5] In contrast to C. conicum and C. salebrosum, the thallus of C. supradecompositum is relatively small, measuring 2 ...
In lichens it refers to the region of the thallus that is free of algae. The prothallus develops from a germinating spore. It is a short-lived and inconspicuous heart-shaped structure typically 2–5 millimeters wide, with a number of rhizoids (root-like hairs) growing underneath, and the sex organs: archegonium (female) and antheridium (male ...
A fungus that lives within the thallus of a lichen without producing any visible symptoms of disease; these fungi are transmitted horizontally. [165] Lecidea laboriosa is an endolithic lichen; the thallus, hardly visible, grows under and around the rock crystals, while the apothecia are visible on the surface. endolith Also endolithic.
Lichens are grouped by thallus type, since the thallus is usually the most visually prominent part of the lichen. Thallus growth forms typically correspond to a few basic internal structure types. Common names for lichens often come from a growth form or color that is typical of a lichen genus. Common groupings of lichen thallus growth forms are:
The thallus (or body) consists of flat or leaf-like structures known as blades that originate from elongated stem-like structures, the stipes. A root-like structure, the holdfast, anchors the kelp to the substrate of the ocean. Gas-filled bladders (pneumatocysts) form at the base of blades of American species, such as Nereocystis lueteana, (Mert.
Caulerpa is coenocytic, meaning it has a multinucleate thallus organization. It is also siphonous, meaning unlike other algae, the thallus and the nuclei are not separated by cell walls. They are instead one long mass of protoplasm surrounded by a single cell wall. [12]
The thallus is perennial with an irregular or disc-shaped holdfast or with haptera. [1] The erect portion of the thallus is dichotomous or subpinnately branched, flattened and with a distinct midrib. Gas-filled pneumatocysts (air-vesicles) are present in pairs in some species, one on either side of the midrib.