dcsimg

Description

provided by Flora of Zimbabwe
Epiphytic or lithophytic perennial plants. Rhizome shortly creeping, dichotomously or laterally branched, with endophytic mycorrhiza, without roots, with short and long rhizoids. Aerial stems linear, chlorophyllous, erect or pendulous, dichotomously branched, simple towards the base. Leaves much reduced, simple, scale-like, lacking a midrib, without ligules. Sporangia in globular, thick-walled synangia composed of 2 or 3 fused sporangia, exindusiate, homosporus.
license
cc-by-nc
copyright
Mark Hyde, Bart Wursten and Petra Ballings
bibliographic citation
Hyde, M.A., Wursten, B.T. and Ballings, P. (2002-2014). Psilotaceae Flora of Zimbabwe website. Accessed 28 August 2014 at http://www.zimbabweflora.co.zw/speciesdata/family.php?family_id=188
author
Mark Hyde
author
Bart Wursten
author
Petra Ballings
original
visit source
partner site
Flora of Zimbabwe

Psilotaceae

provided by wikipedia EN

Psilotaceae is a family of ferns (class Polypodiopsida) consisting of two genera, Psilotum and Tmesipteris with about a dozen species.[1] It is the only family in the order Psilotales.[2]

Description

The first genus, Psilotum, consists of small shrubby plants of the dry tropics commonly known as "whisk ferns". The other genus, Tmesipteris, is an epiphyte found in Australia, New Zealand, and New Caledonia. Once thought to be descendants of the first vascular plants (the Psilophyta of the Devonian period), they have been shown by molecular phylogenetics to be ferns, a sister group of the Ophioglossaceae.

All Psilotaceae share a few characteristics. They are vascular plants and they lack leaves, having instead small outgrowths called enations. The enations are not considered true leaves because there is only a vascular bundle just underneath them, but not inside, as in leaves. Psilotales also do not have true roots. They are anchored by rhizoids. Absorption is aided by symbiotic fungi called mycorrhizae.

Three sporangia are united into a synangium, which is considered to be a very reduced series of branches. There is a thick tapetum to nourish the developing spores, as is typical of eusporangiate plants. The gametophyte looks like a small piece of subterranean stem, but produces antheridia and archegonia.

Classification

In the molecular phylogenetic classification of Smith et al. in 2006, Psilotales, containing the single family Psilotaceae comprising Psilotum and Tmesipteris, was placed with the order Ophioglossales in the class Psilotopsida.[3] The linear sequence of Christenhusz et al. (2011), intended for compatibility with the classification of Chase and Reveal (2009)[4] which placed all land plants in Equisetopsida,[5] made it a member of subclass Ophioglossidae, equivalent to Smith's Psilotopsida.[4] The placement of Psilotales in subclass Ophioglossidae has subsequently been followed in the classifications of Christenhusz and Chase (2014)[6] and PPG I (2016).[2]

In the past Tmesipteris has been placed in its own family, Tmesipteridaceae,[7] but this has not been maintained in the system of Smith et al. and later classifications.

References

  1. ^ Christenhusz, M. J. M. & Byng, J. W. (2016). "The number of known plants species in the world and its annual increase". Phytotaxa. Magnolia Press. 261 (3): 201–217. doi:10.11646/phytotaxa.261.3.1.
  2. ^ a b The Pteridophyte Phylogeny Group (November 2016). "A community-derived classification for extant lycophytes and ferns". Journal of Systematics and Evolution. 54 (6): 563–603. doi:10.1111/jse.12229.
  3. ^ Smith, Alan R.; Pryer, Kathleen M.; Schuettpelz, Eric; Korall, Petra; Schneider, Harald; Wolf, Paul G. (August 2006). "A classification for extant ferns" (PDF). Taxon. 55 (3): 705–731. doi:10.2307/25065646. JSTOR 25065646.
  4. ^ a b Christenhusz, Maarten J. M.; Zhang, Xian-Chun; Schneider, Harald (18 February 2011). "A linear sequence of extant families and genera of lycophytes and ferns" (PDF). Phytotaxa. 19: 7–54. doi:10.11646/phytotaxa.19.1.2. hdl:10138/28042.
  5. ^ Chase, Mark W.; Reveal, James L. (October 2009). "A phylogenetic classification of the land plants to accompany APG III". Botanical Journal of the Linnean Society. 161 (2): 122–127. doi:10.1111/j.1095-8339.2009.01002.x.
  6. ^ Christenhusz, Maarten J. M.; Chase, Mark W. (13 February 2014). "Trends and concepts in fern classification". Annals of Botany. 113 (4): 571–594. doi:10.1093/aob/mct299. PMC 3936591. PMID 24532607.
  7. ^ K. U. Kramer (1990). "Psilotaceae". In Kramer, K. U.; Green, P. S. (eds.). The Families and Genera of Vascular Plants. I. Berlin: Springer Verlag. p. 22. ISBN 3-540-51794-4.

 title=
license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN

Psilotaceae: Brief Summary

provided by wikipedia EN

Psilotaceae is a family of ferns (class Polypodiopsida) consisting of two genera, Psilotum and Tmesipteris with about a dozen species. It is the only family in the order Psilotales.

license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN