from The American Heritage® Dictionary of the English Language, 5th Edition.
- adjective Of, resembling, or constituting a thallus.
from The Century Dictionary.
- In botany, resembling or consisting of a thallus.
from the GNU version of the Collaborative International Dictionary of English.
- adjective (Bot.) Resembling, or consisting of, thallus.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- adjective Of or pertaining to a
- adjective botany Of a
plant, alga, or funguslacking complex organization, especially lacking distinct stems, roots, or leaves.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adjective of or relating to or resembling or consisting of a thallus
Sorry, no etymologies found.
The familiar duckweed which covers the surface of a pond consists of a tiny green "thalloid" shoot, one, that is, which shows no distinction of parts -- stem and leaf, and a simple root growing vertically downwards into the water.
The Marchantiales are a series of thalloid forms, in which the structure of the thallus is specialized to enable them to live in more exposed situations.
The characteristics, then, of the mosses are, that the sexual generation is leafy, the one or two asexual generations are thalloid, and that the spore-bearing generation is in parasitic connection with the sexual generation.
The sexual generation is a small green thalloid structure called a prothallium, which bears antheridia and archegonia, each archegonium having a neck-canal and oosphere, which is fertilized just as in the moss.
In thalloid forms a thinner marginal expansion or a definite wing increasing the surface exposed to the light can be distinguished from a thicker midrib serving for storage and conduction.
The spore on germination forms a short filament which soon broadens out into the thalloid protonema.
In thalloid forms fimbriate or lobed margins or outgrowths from the surface lead to the same result.
The lower members of the Jungermanniales are also thalloid, but the thallus never has the complicated structure characteristic of the Marchantiales, and progress is in the direction of the differentiation of the plant into stem and leaf.
In thalloid forms the sexual organs are often sunk in depressions, while in the foliose forms protection is afforded by the surrounding leaves.
The protonema forms a flat, lobed, thalloid structure attached to the soil by rhizoids, and the plants arise from marginal cells.