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The analogous structures have similar function or macroscopic structure, but different microscopic structure; for example, no thallus has vascular tissue. In exceptional cases such as the Lemnoideae, where the structure of a vascular plant is in fact thallus-like, it is referred to as having a thalloid structure, or sometimes as a thalloid.
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 ...
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 ...
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:
A byssoid lichen has a wispy, cottony or teased wool appearance due to the loosely woven hyphae in its thallus. [13] It has no outer cortex. [14] Lichens with this growth type can be split into two types. In one type, the thallus is dominated by fungal hyphae, with a photobiont – typically a coccoid green alga – sprinkled throughout. In the ...
The thallus contains specialised sclerotic cells in its ventral region that serve as conducting tissue, though these differ from true tracheids in both form and function. These sclerotic cells are elongated, thick-walled, dark brown, fibre-like cells with pointed ends that typically occur singly, though occasionally two or three may be found ...
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.
Male conceptacles tend not to sit as deep within the thallus as female conceptacles; their size is similar although their shape tends to differ. [8] Cells within circular regions within the perithallus lengthen to form sexual conceptacles, [ 8 ] leaving long, wefty cells around the walls of the conceptacle. [ 14 ]