THALLUS

thallus

(noun) a plant body without true stems or roots or leaves or vascular system; characteristic of the thallophytes

Source: WordNet® 3.1

Etymology

Noun

thallus (plural thalli)

(botany) An undifferentiated plant body, such as in algae.

(botany) Any plant body lacking vascular tissue.

Source: Wiktionary

Thal"lus, n.; pl. Thalli. Etym: [NL., fr. Gr. (Bot.)

Definition: A solid mass of cellular tissue, consisting of one or more layers, usually in the form of a flat stratum or expansion, but sometimes erect or pendulous, and elongated and branching, and forming the substance of the thallogens.

Source: Webster’s Unabridged Dictionary 1913 Edition