Thallus


Thallus

: "For the chronologer/historian occasionally mentioned in the works of early Christian writers, see Thallus (historian)."

Thallus, from Latinized Greek θαλλος ("thallos"), meaning "a green shoot" or "twig", is an undifferentiated vegetative tissue of some non-mobile organisms, which were previously known as the thallophytes.

An organism or structure resembling a thallus is called thalloid, thallodal, thalliform, thalline, or thallose.

Even though thalli do not have organized and distinct parts (leaves, roots, and stems) as do the vascular plants, they may have analogous structures that resemble their vascular "equivalents". The analogous structures have similar function or macroscopic structure, but different microscopic structure; for example, no thallus has vascular tissue.

Although a thallus is largely undifferentiated in terms of its anatomy, there can be visible differences and functional differences. A kelp, for example, may have its thallus divided into three regions. The parts of a kelp thallus include the holdfast (anchor), stipe (supports the blades) and the blades (for photosynthesis).

The thallus of a fungus is usually called a mycelium. In seaweed, thallus is sometimes also called "frond".

The gametophyte of some non-thallophyte plants -- clubmosses, horsetails, and ferns is termed "prothallus".


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  • THALLUS° — (Gr. θαλλος), a first century C.E. author (probably heathen) of a lost Greek universal chronicle in three books of which eight fragments survive. Thallus main theme was Hellenic rather than biblical history. Freudenthal suggested that Thallus was …   Encyclopedia of Judaism

  • Thallus — Thal lus, n.; pl. {Thalli}. [NL., fr. Gr. ? young shoot or branch, frond.] (Bot.) 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… …   The Collaborative International Dictionary of English

  • thallus — thallus. См. слоевище. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Thallus — (Th. Ach.), das Laub der Flechten, an der Erde, auf Steinen, Mauern, Felsen, Baumrinde od. Holz, in Gestalt einer gelappten blattartigen od. harten rindenartigen od. schorfartigen Masse, auf welcher sich schild , becherförmige etc. Behälter… …   Pierer's Universal-Lexikon

  • Thallus — (griech., Thallom, Laub, Lager), alle Pflanzenkörper, an denen diejenigen Gliederungen, Wachstumgesetze und Einrichtungen des innern Baues, welche die Merkmale vom Stengel, Wurzel und Blatt ausmachen, nicht wahrzunehmen sind, wie bei allen Pilzen …   Meyers Großes Konversations-Lexikon

  • Thallus — (grch.), Thallōm, Lager, Pflanzenkörper, der nicht in Wurzel, Stamm und Blatt gegliedert ist (Pilze, Flechten, Algen) …   Kleines Konversations-Lexikon

  • Thallus — Thallus, Pflanzenkörper der ⇒ Thallophyten, der aus Zellen, die durch gemeinsame Zellwände verbunden und arbeitsteilig spezialisiert sind, besteht und nicht die Merkmale eines typischen ⇒ Cormus besitzt. In der Stammesgeschichte ist es mehrfach… …   Deutsch wörterbuch der biologie

  • thallus — Latin, from Gk. thallos green shoot, twig, related to thalia abundance, thalos scion, child, ultimately from PIE root *dhal to bloom (Cf. O.Ir. duilesc, a type of algae) …   Etymology dictionary

  • thallus — [thal′əs] n. pl. thalli [thal′ī΄] or thalluses [ModL < Gr thallos, young shoot: see THALIA] the nonvascular plant body of a thallophyte, showing no clear distinction of roots, stem, or leaves thalloid [thal′oid΄] adj …   English World dictionary

  • Thallus — Der Thallus, zu deutsch auch Lager, ist der vielzellige Vegetationskörper bei Pflanzen, der nicht in Sprossachse, Wurzel und Blatt unterteilt ist. Solche Pflanzen nennt man Thallophyten oder Lagerpflanzen. Der Thallus kann nur negativ definiert… …   Deutsch Wikipedia


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