Cyatheaceae

Cyathea medullaris

The Cyatheaceae are a family of tree ferns ( Cyatheales ).

Features

The Cyatheaceae usually form upright stems with a polycyclic Dictyostele. The shoot tip and usually also the petiole bases are covered with large scales, sometimes equipped with a small shed ( Trichomidien ) or with hair. The leaves are usually large and reach 5 m in length. The petiole has two conspicuous Pneumathoden. The leaf blades are feathered one to three times, rarely are they undivided. The nerves are branches simple or forked, free or rarely end anastomosis (usually at Cyathea ).

The sori are on the underside of leaves or terminal to the nerves, on the leaf margin ( marginal) or close to it ( submarginal in Hymenophyllopsis ). The sori are round, without indusia or with saucers, cup-shaped or spherical indusia. In Hymenophyllopsis the indusia are zweiklappig. The sporangia ripen after row, the annulus is dark. Most occur paraphyses. The spores are tetrahedral, trilet ( three-rayed scar ) and ornamented differently.

The gametophyte is green and heart-shaped.

The basic chromosome number is x = 69

Dissemination

The family is widespread in the tropics worldwide. In the Earth are representative of the family since the Jurassic or Early Cretaceous known.

System

The Cyatheacae consists of five genera and about 600 species. Herein we describe the extent it is monophyletic. Smith et al. (2006) provide the following genera:

  • Alsophila R. Br (incl. Nephelea RM Tryon ), with at least about 63 species
  • Cyathea Sm (including Cnemidaria C.Presl, Hemitelia R. Br, Trichipteris C. Presl ), with at least about 280 species
  • Gymnosphaera flower, with about 21 species
  • Hymenophyllopsis K.I. Goebel with 8 kinds and thin sheets without stomata. The genus is restricted to the tepuis in the Guayana Highlands.
  • Sphaeropteris Bernh. (including Fourniera Scribn. ), with at least 13 species.

More detailed phylogenetic analyzes revealed the following relationships:

Cyathea (including Hymenophyllopsis )

Alsophila S. S.

Gymnosphaera (including Alsophila capensis )

Sphaeropteris

Documents

  • Alan R. Smith, Kathleen M. Pryer, Eric Schuettpelz, Petra coral, Harald Schneider, Paul G. Wolf: A classification for extant ferns. In: taxon. Volume 55, No. 3, 2006, ISSN 0040-0262, pp. 705-731, Abstract, PDF file.
  • David John Mabberley: The Plant-Book. A portable dictionary of the higher plants. Cambridge University Press 1987. ISBN 0-521-34060-8
Leptosporangiate fern Stele (biology) Sorus
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