thal·lus / ˈ[unvoicedth]aləs/ •
n. (pl. thal·li / ˈ[unvoicedth]alī/ ) Bot. a plant body that is not differentiated into stem and leaves and lacks true roots and a vascular system. Thalli are typical of algae, fungi, lichens, and some liverworts.DERIVATIVES: thal·loid / ˈ[unvoicedth]aloid/ adj.
A primitive type of vegetative plant body that is not differentiated into stems, leaves, and roots, although analogous
structures may be present. The term is used mainly of non-vascular plants, e.g. algae
, and liverworts
. See also THALLOPHYTE
A relatively undifferentiated vegetative body with no true roots, stems, leaves, or vascular system
. It is found in the algae, fungi, mosses, and liverworts and in the gametophyte generation of clubmosses, horsetails, and ferns.