Blechnoideae

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Blechnoideae
Blechnum spicant2.jpg
Blechnum spicant
Scientific classification
Kingdom: Plantae
(unranked): Polypodiophyta
Subclass: Polypodiidae
Order: Polypodiales
Family: Aspleniaceae
Subfamily: Blechnoideae
Hook
Type genus
Blechnum
Genera

See text

Blechnoideae is a subfamily of between 240 and 260 species of ferns, with a cosmopolitan distribution.

Description[edit]

Most are ground dwelling, some are climbers, such as Stenochlaena. A characteristic feature of many species is that the young opening fronds are usually tinged with red.

Taxonomy[edit]

Earlier classifications[edit]

Previously treated as a separate family, Blechnaceae Newman,[1][2] in 2014 Christenhusz and Chase submerged it as subfamily Blechnoideae within family Aspleniaceae.[3]

Originally considered as a member of the Eupolypods II clade, in the order Polypodiales,[4] in the class Polypodiopsida.[2] the Blechnaceae was related to other families in the clade as in this cladogram:[5][4]

eupolypods II

Cystopteridaceae





Rhachidosoraceae




Diplaziopsidaceae




Aspleniaceae



Hemidictyaceae







Thelypteridaceae




Woodsiaceae





Onocleaceae



Blechnaceae




Athyriaceae







Christenhusz and Chase classification[edit]

Blechnoideae is placed within the Aspleniaceae as follows:[3]

Aspleniaceae

Cystopteridoideae (Acystopteris, Cystoathyrium, Cystopteris, Gymnocarpium)





Rhachidosoroideae (Rhachidosorus)




Diplaziopsidoideae (Diplaziopsis, Homalosorus)



Asplenioideae (Asplenium, Hemidictyum, Hymenasplenium)






Thelypteridoideae (Macrothelypteris, Phegopteris, Thelypteris)




Woodsioideae (Woodsia)




Blechnoideae (Blechnum, Onoclea, Stenochlaena, Woodwardia)



Athyrioideae (Athyrium, Cornopteris, Deparia, Diplazium)







Subdivision[edit]

The number of genera recognized within Blechnoideae (Blechnaceae) vary greatly between authors,[1][6][7] but has generally been between eight and ten. Of the approximate 200 species, the vast majority are attributed to Blechnum L., followed by Woodwardia Sm. with about 14 species and Stenochlaena J.Sm. with six. Other genera are largely monotypic.[8]

Christenhusz and Chase (2014) describe the situation as follows: "Blechnoideae comprise three major clades, one corresponding to Onoclea sensu lato, a second corresponding to Woodwardia, sister to all other species that can be treated as the single genus Blechnum. However, the subclade sister to the rest of Blechnum sensu lato contains the vining taxa Stenochlaena, Salpichlaena J.Sm. and a few non-vining Blechnum species with long-creeping rhizomes, which may have to be accepted at the generic level pending further studies. Brainea, Doodia, Pteridoblechnum and Sadleria belong to Blechnum sensu lato."[3]

Perrie et al. (2014) simultaneously identified three major clades, which they labelled Woodwardia, super- Stenochlaena and super-Blechnum, with the latter two as sister groups. They retained the family rank and excluded Onoclea as a separate family, Onocleaceae as sister to Blechnaceae. They did not consider Blechnum as monophyletic and recommended revision of intergeneric boundaries, resulting in seven genera.[8]

Gasper et al. (2016), independently of Christenhusz and Chase examined the deeper relationships of the Blechnoideae, while retaining its family status and excluding Onocleaceae, and allocated these clades to subfamilies, Blechnoideae, Woodwardioideae, and Stenochlaenoideae respectively. Their approach to the polyphyletic nature of Blechnum was to create a series of monophyletic segregate genera, resulting in 24 genera in total. If Blechnoideae is considered a subfamily sensu Christenhusz and Chase these would more properly be considered as tribes.[6][7] But the latter treat the Blechnoideae as only three genera. Blechnum sensu lato (including Stenochlaena), Woodwardia and Onoclea sensu lato (including Matteuccia Tod., Onocleopsis F.Ballard and Pentarhizidium Hayata), while conceding the possibility of treating Blechnum as two sister genera, Blechnum (including Brainea, Doodia, Pteridoblechnum and Sadleria) and Stenochlaena.

Their clades are related as follows:

Blechnoideae


Blechnum



Woodwardia




Onoclea



References[edit]

  1. ^ a b Maarten J. M. Christenhusz; Xian-Chun Zhang & Harald Schneider (2011). "A linear sequence of extant families and genera of lycophytes and ferns" (PDF). Phytotaxa. 19: 7–54. 
  2. ^ a b Smith et al 2006.
  3. ^ a b c Christenhusz & Chase 2014.
  4. ^ a b Carl J. Rothfels; Anders Larsson; Li-Yaung Kuo; Petra Korall; Wen- Liang Chiou; Kathleen M. Pryer (2012). "Overcoming Deep Roots, Fast Rates, and Short Internodes to Resolve the Ancient Rapid Radiation of Eupolypod II Ferns". Systematic Biology. 61 (1): 490–509. PMID 22223449. doi:10.1093/sysbio/sys001. 
  5. ^ Samuli Lehtonen (2011). Steinke, Dirk, ed. "Towards Resolving the Complete Fern Tree of Life" (PDF). PLoS ONE. 6 (10): e24851. PMC 3192703Freely accessible. PMID 22022365. doi:10.1371/journal.pone.0024851. 
  6. ^ a b Gasper et al 2016.
  7. ^ a b Gasper et al 2016a.
  8. ^ a b Perrie et al 2014.

Bibliography[edit]

External links[edit]