HEDWIGIACEAE

 

Efrain De Luna,

Biodiversidad y Sistemática,

INECOL. Xalapa. México.

web

Phylogenetic classification

Hedwigiaceae

Keys to genera

Braunia

Hedwigia

Hedwigidium

Pseudobraunia (link to Flora of North America)

 

The Hedwigiaceae consists of four genera (De Luna, 1995):

  • Braunia Bruch & Schimp. in B.S.G.,
  • Pseudobraunia (Lesq. & James) Broth.
  • Hedwigia P. Beauv.,
  • Hedwigidium Bruch & Schimp. in B.S.G.

The gametophytes in all species in the family are acrocarpous, and the branching is sympodial (De Luna, 1990a). At the base of branches, there are pseudoparaphylia, whith papillose cells. The habit is plagiotropous and postrate, thus reseambling a pleurocarpous matt. Most species grow over igneous rocks.

Leaves are ecostate. The upper leaf cells are subquadrate to rectangular thick-walled, often sinuose, and with central or marginal cell papillae. The pattern of leaf cell aerolation consists of mostly subquadrate cells aligned in longitudinal rows.

The sporophyrtes in all species of the family have capsules without peristomes. Spores can be multicelular and most species have unicellular spores. Spore germination produces a globular protonemata (De Luna 1990b).

The gametophytes of Hedwigia and Pseudobraunia are very similar in leaf shape, hyaline acumens, and tall papillae centrally placed over the cell lumen. It is a matter of ranking if these two genera are considered synonymous (De Luna 1992) or if they are considered different. The sporophytes are different in setae lengths, very short in Hedwigia, and long in Pseudobraunia.

The gametophytes of Hedwigidium and Braunia are also very similar. Leaves are more or less ovate to oblong and leaf cell papillae are marginal overarching the cell lumen.


Braunia is the largest genus in the family with 23 species. The other three genera were considered monotypic for a long time. Recent phylogenetic work in Hedwigia has proven that this genus at least consist of  9 species. A similar situation may result after Hedwigidium is studied in detail.

 

 

Figs 6-10 from: De Luna 1995.

Plate 1 from: Fife 2014. Hedwigiaceae. Flora of New Zealand.

 

De Luna E. 1990a. Developmental evidence of acrocarpy in Hedwigia ciliata (Musci: Hedwigiaceae). Tropical Bryology 2: 53 60.

De Luna E. 1990b. Protonemal development in the Hedwigiaceae (Musci), and its systematic significance. Systematic Botany 15: 192-204.

De Luna, E. 1995: The circumscription and phylogenetic relationships of the Hedwigiaceae (Musci). Systematic Botany 20: 347–373.

 

Pseudobraunia californica

Hedwigia, Hedwigidium and Braunia growing on a volcanic rock, central Veracruz

 

Hedwigia, Braunia and Hedwigidium growing together on rock. Cofre de Perote volcano, Mexico