Marchantia

• Authority

  Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)

• Family

  Marchantiaceae

• Scientific Name

  Marchantia

• Type

  Type species (Leman, 1823). Marchantia polymorpha L. (lectotype). Genus dedicated to N. Marchant (... -1678), Director of the Garden of Due Gaston d Orleans.

• Synonyms

  Marchantia polymorpha L.

• Description

  Genus Description - Thallus 2.7-20 mm wide, often tinged with purple. Branching dichotomous. Epidermal pores compound, with 4-7 rings of cells, radial walls thin. Air chambers in 1 layer, with chlorophyllose filaments. Basal tissue with oil cells, often with sclerotic cells and mucilage cavities. Rhizoids smooth and tuberculate. Ventral scales in 4-10 rows, with oil cells and marginal papillae, each pair of rows of different shape, the 2 median with large appendage. Asexual reproduction by discoid gemmae with 2 growing points. Gemma cups cup-shaped. Dioecious, rarely with male branches developing in the female receptacles and then monoecious. Antheridiophore terminal; stalk with 0-2 assimilatory strips, 2-4 rhizoid furrows and scales, sometimes with modified ventral thallus scales sheathing the base; receptacle peltate or palmate, 2-to 12-lobed, with compound pores on dorsal side and scales underneath. Archegoniophore terminal; stalk with 1-2 assimilatory strips, 2-4 rhizoid furrows, and scales, sometimes with modified ventral thallus scales sheathing the base; receptacle 2- to 13-lobed, with compound pores on dorsal side. Involucres bilabiate, alternating with the receptacular lobes in neotropical species. Archegonia 2-14 per archegonial cavity, each fertilized archegonium enclosed within a campanulate pseudoperianth. Calyptrae 2- to 3-layered after fertilization. Sporophytes several per involucre, maturing sequentially; mature sporophyte with slightly elongating seta; capsule splitting into irregular valves to 1/2 of capsule length, walls with annular thickenings; spore/elater ratio more than 4:1. Spores 5000 to more than 10,000 per capsule, 8-36 |Lim diam., distal face either with tuberculate areoles, or with ridges and depressions, or irregularly pitted or grooved, or vermiculate, proximal face usually irregularly pitted or vermiculate, trilete scar ±; distinct. Elaters with 2-3 helical bands. Gametophytic chromosome number n = 9 or 18.

• Discussion

  Marchantia is a genus of worldwide distribution, comprising 36 species. They occur predominantly in humid-temperate, subtropical, and tropical areas without pronounced dry seasons. Some species reach the Arctic and the Antarctic. All are terrestrial and grow on bare or rocky soil, exposed or shaded by open vegetation. They avoid the shaded understory of forests but are common at forest edges and along roads inside the forests. They are indifferent to edaphic conditions (type of rocks, or soil, or pH) but are not drought-tolerant; the substratum has to be permanently moist. Newly opened habitats where space is available, especially open, ruderal, and disturbed, human-made sites are frequently colonized. The distributions of some taxa seems to be limited by high or low temperatures, but the availability of water and free space are the main conditions determining their geographical ranges. They grow from sea level up to 4500 m but are rare in equatorial lowland areas.

  Marchantia species are among the most common thallose liverworts in the Neotropics. The genus is represented by 2 (out of 3) subgenera and 8 species. Four of them have large ranges, including more than one continent, the four others are known from the New World alone.
  Marchantia foliacea Mitt, from S Chile, Juan Fernandez, Australia, and New Zealand does not occur in the Neotropics and has been excluded from this treatment.
  Invalid names are not cited among the synonyms of the species. They are listed in Bischler (1984).