Metzgeriales

Metzgeriales Temporal range: Upper Devonian to recent
Riccardia multifida
Scientific classification
Kingdom:	Plantae
Division:	Marchantiophyta
Class:	Jungermanniopsida
Order:	Metzgeriales Chalaud, 1930
Families
Allisoniaceae Aneuraceae Calyculariaceae Fossombroniaceae Hymenophytaceae Makinoaceae Metzgeriaceae Mizutaniaceae Moerckiaceae Pallaviciniaceae Pelliaceae Petalophyllaceae Phyllothalliaceae Sandeothallaceae † Metzgeriites See also classification.
Synonyms
Anacrogynae (various authors) Frondosae Endlicher, 1841

Allisoniaceae
Aneuraceae
Calyculariaceae
Fossombroniaceae
Hymenophytaceae
Makinoaceae
Metzgeriaceae
Mizutaniaceae
Moerckiaceae
Pallaviciniaceae
Pelliaceae
Petalophyllaceae
Phyllothalliaceae
Sandeothallaceae
† Metzgeriites

Anacrogynae (various authors)
Frondosae Endlicher, 1841

Metzgeriales is an order of liverworts. The group is sometimes called the simple thalloid liverworts: "thalloid" because the members lack structures resembling stems or leaves, and "simple" because their tissues are thin and relatively undifferentiated. All species in the order have a small gametophyte stage and a smaller, relatively short-lived, spore-bearing stage. Although these plants are almost entirely restricted to regions with high humidity or readily available moisture, the group as a whole is widely distributed, and occurs on every continent except Antarctica.

Members of the Metzgeriales typically are small and thin enough to be translucent, with most of the tissues only a single cell layer in thickness. Because these plants are thin and relatively undifferentiated, with little evidence of distinct tissues, the Metzgeriales are sometimes called the "simple thalloid liverworts".

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Wikipedia