Lihat sumber Cakar ayam (Tumbuhan)

{{Automatic taxobox 
| name = Cakar ayam<br/> (''Selaginella'')
| image = Selaginella-sp.jpg
| taxon = Selaginella
| authority = [[Ambroise Marie François Joseph Palisot de Beauvois|P. Beauv.]]
| subdivision_ranks = Spesies
| subdivision = Lihat teks.
 | parent_authority=[[Heinrich Moritz Willkomm|Willk.]]
 | grandparent_authority=[[Karl Anton Eugen Prantl|Prantl]]
 | image_width=240px
}}

'''Paku cakar ayam''' ('''''Selaginella''''') adalah marga sekelompok tumbuhan berpembuluh yang merupakan satu-satunya anggota suku [[Selaginellaceae]]. Tumbuhan ini berkembang biak dengan [[spora]] bebas sehingga dianggap sebagai bagian dari [[tumbuhan paku]] (Pteridophyta). Namun demikian, melalui teknik [[Biologi molekuler|molekuler]] sekarang diketahui bahwa rane bersama-sama [[Lycopodiopsida|paku kawat]], kumpai, dan ''[[Isoetes]]'' tergabung dalam satu [[divisio]] tersendiri, [[Lycopodiophyta]], yang merupakan sepupu bagi [[Tumbuhan berpembuluh|Tracheophyta]] lainnya, yaitu [[Tumbuhan paku|tumbuhan paku sejati]]  dan [[tumbuhan berbiji]].

Paku cakar ayam memiliki ciri daun kecil dan sederhana (disebut mikrofil) yang menyerupai sisik pipih dan duduk (tidak bertangkai), serta [[spora|heterosporik]] (menghasilkan dua tipe [[spora]] yang berbeda ukurannya). Pertumbuhan cabang dan daunnya tidak berupa gulungan membuka seperti paku sejati, sehingga memang sebenarnya rane dan kumpai bukanlah tumbuhan paku.
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 ''[[Selaginella moellendorffii|S. moellendorffii]]'' is an important [[model organism]]. Its genome has been sequenced by the [[United States Department of Energy]]'s [[Joint Genome Institute]].<ref>{{cite web |url=http://genomeportal.jgi-psf.org/Selmo1/Selmo1.home.html |title=''Selaginella moellendorffii'' v1.0 |year=2007 |work=[[Joint Genome Institute]] |publisher=[[United States Department of Energy]] |accessdate=2009-04-08}}</ref>
==Characteristics==
''Selaginella'' species are creeping or ascendant plants with simple, scale-like leaves ([[microphylls]]) on branching stems from which roots also arise. The plants are [[spore|heterosporous]] (megaspores and microspores), and have structures called ligules, scale-like outgrowths near the base of the upper surface of each microphyll and sporophyll. Under dry conditions, some species of ''Selaginella'' roll into brown balls (a phenomenon known as [[poikilohydry]]). In this state, they may be uprooted. Under moist conditions the brown balls become green, because of which these are also known as [[resurrection plants]] (as in ''Selaginella bryopteris'').

Unusually for the lycopods, each microphyll contains a branching vascular trace.

==Generic division==
Many scientists{{who|date=June 2014}} still place the Selaginellales in the class [[Lycopodiopsida]] (often misconstructed as "Lycopsida").{{citation needed|date=June 2014}} Some modern authors recognize three generic divisions of ''Selaginella'': ''Selaginella'', ''Bryodesma'' <small>Sojak 1992</small>, and ''Lycopodioides'' <small>Boehm 1760</small>.  ''Lycopodioides'' would include the North American species ''S. apoda'' and ''S. eclipes'', while ''Bryodesma'' would include ''S. rupestris'' (as ''Bryodesma rupestre''). ''Stachygynandrum'' is also sometimes used to include the bulk of species.

The first major attempt to define and subdivide the group was by [[Palisot de Beauvois]]<ref>Palisot de Beauvois (1805): ''Prodrome des cinquième et sixième familles de l'Æthéogamie, les mousses, les lycopodes.''</ref> in 1803-1805.  He established the genus ''Selaginella'' as a monotypic genus, and placed the bulk of species in ''Stachygynandrum''. ''Gymnogynum'' was another monotypic genus, but that name is superseded by his own earlier name of ''Didiclis''.  This turns out, today, to be a group of around 45-50 species also known as the ''Articulatae'', since his ''Didiclis/Gymnogynum'' genus was based on ''[[Selaginella plumosa]]''.  He also described the genus ''Diplostachyum'' to include a group of species similar to ''Selaginella apoda''.  [[Antoine Frédéric Spring|Spring]] inflated the genus ''Selaginella'' to hold all selaginelloid species four decades later.

Phylogenetic studies by Korall & Kenrick<ref>{{Citation |last=Korall |first=P. |last2=Kenrick |first2=P. |year=2002 |title=Phylogenetic relationships in Selaginellaceae based on ''rbcL'' sequences |journal=American Journal of Botany |volume=89 |issue=3 |pages=506–17 |lastauthoramp=yes |doi=10.3732/ajb.89.3.506}}</ref><ref>Korall & Kenrick (2004): The phylogenetic history of Selaginellaceae based on DNA sequences from the plastid and nucleus: extreme substitution rates and rate heterogeneity. ''Molecular Phylogenetics and Evolution'', Volume 31, Issue 3, June 2004, Pages 852-864</ref> determined that the ''Euselaginella'' group, comprising solely the type species, ''[[Selaginella selaginoides]]'' and a closely related Hawaiian species, ''Selaginella deflexa'', is a basal and anciently diverging sister to all other ''Selaginella'' species. Beyond this, their study split the remainder of species into two broad groups, one including the ''Bryodesma'' species, the ''Articulatae'', section ''Ericetorum'' <small>Jermy</small> and others, and the other centered around the broad ''Stachygynandrum'' group.

In the ''Manual of Pteridology'',<ref>Verdoorn, F., ed. (1938): Manual of Pteridology: J. Walton and A. H. G. Alston, Lycopodinae, pp. 500-506. Martinus Nijhoff, The Hague. 640pp, HB.</ref> the following classification was used by Walton & Alston:

'''genus: ''Selaginella'''''
*subgenus: ''Euselaginella''
**group: ''selaginoides''
**group: ''pygmaea''
**group: ''uliginosa'' (''Ericetorum'')
**group: ''rupestris'' (''Tetragonostachys'' or ''Bryodesma'')
*subgenus: ''Stachygynandrum''
**series: ''Decumbentes''
**series: ''Ascendentes''
**series: ''Sarmentosae''
**series: ''Caulescentes''
**series: ''Circinatae''
**series: ''Articulatae''
*subgenus: ''Homostachys''
*subgenus: ''Heterostachys''

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== Spesies ==
Ada sekitar 700 spesies anggota ''Selaginella'', dengan kecenderungan untuk pemisahan sampai aras marga karena hasil penelitian-penelitian terkini memperlihatkan pengelompokan yang semakin jelas. Berikut adalah jenis-jenis yang cukup dikenal, karena memiliki kekhasan perilaku, ekologi, atau menjadi tanaman hias populer.
* ''[[Selaginella apoda]]'' <small></small>(L.) Spring) - dari Amerika Utara dan menjadi tanaman hias untuk kawasan beriklim sedang
* ''[[Selaginella arizonica]]'' Maxon - berasal dari Amerika Serikat barat daya dan Meksiko utara
* ''[[Selaginella asprella]]''
* ''[[Selaginella bifida]]'' <small></small>- asal dari [[Pulau Rodrigues]]
* ''[[Selaginella biformis]]'' <small></small>
* ''[[Selaginella bigelovii]]''
* ''[[Selaginella braunii]]'' <small></small> Baker - berasal dari [[Tiongkok]]
* ''[[Selaginella bryopteris]]'' <small></small> - berasal dari [[India]]
* ''[[Selaginella canaliculata]]'' <small></small> - dari [[Asia Tenggara]] dan [[Malesia]] hingga ke [[Maluku]] 
* ''[[Selaginella carinata]]'' <small></small>- 
* ''[[Selaginella cinerascens]]''
* ''[[Selaginella densa]]'' <small></small> - asal dari Amerika Utara bagian barat
* ''[[Selaginella elmeri]]''<small></small>
* ''[[Selaginella eremophila|Selaginella eremop]]''<small></small>''[[Selaginella eremophila|hila]]'' Maxon
* ''[[Selaginella erythropus]]'' (Mart.) Spring - asal [[Hindia Barat]] dan bagian utara [[Amerika Selatan]]
* ''[[Selaginella grandis]]'' T. Moore - dari [[Kalimantan]]
* ''[[Selaginella hansenii|Selaginella haematodes]] (''Kunze) Spring
* ''[[Selaginella inaequalifolia]]'' (Hook. & Grev.) Spring - dari India sampai [[Jawa]]
* ''[[Selaginella involvens]]'' (Sw.) Spring - berasal dari India, [[Sri Lanka]], Tiongkok, Jepang, Asia Tenggara sampai Jawa
* ''[[Selaginella kraussiana]]'' <small></small>(Kunze) A. Braun -  berasal dari Kepulauan [[Azores]] dan menyebar luas ke berbagai penjuru dunia sebagai tanaman penutup tanah ("rumput lumut")
* ''[[Selaginella lepidophylla]]'' <small></small> - "resurrection plant", "flower of stone"  dari [[Gurun Chihuahua]], Amerika Utara
* ''[[Selaginella martensii]]'' Spring - asal Meksiko, dikenal sebagai tanaman hias pot
* ''[[Selaginella moellendorffii]]'' <small></small>
* ''[[Selaginella oregana]]''
* ''[[Selaginella plana]]''<small></small>  (Desv.) Hieron. -  dari Asia tropika
* ''[[Selaginella poulteri]]''
* ''[[Selaginella pulcherrima]]''
* ''[[Selaginella repanda]]''
* ''[[Selaginella rupestris]]'' <small></small> - asal Amerika Utara
* ''[[Selaginella rupincola]]'' Underw. - asal dari Amerika Utara bagian barat daya
* ''[[Selaginella selaginoides]]'' <small></small> - dijumpai di daerah beriklim sedang bumi belahan utara
* ''[[Selaginella sericea]]'' <small>[[A.Braun]]</small> - [[Ekuador]]
* ''[[Selaginella serpens]]''
* ''[[Selaginella tortipila]]''
* ''[[Selaginella uliginosa]]'' [[Australia]]
* ''[[Selaginella umbrosa]]''
* ''[[Selaginella uncinata]]'' <small></small> - rane biru
* ''Selaginella underwoodii'' Hieron - dari Amerika Serikat barat daya
* ''[[Selaginella wallacei]]''
* ''[[Selaginella watsonii]]''
*''[[Pakis merak|Selaginella willdenowii]]'' (Desv. ex Poiret) Baker – '''Pakis merak'''

Beberapa jenis ''Selaginella'' merupakan tanaman gurun yang dikenal sebagai ''resurrection plants'' karena jika kekeringan akan mengerut menjadi bola kemerahan namun membuka dan hijau segar ketika mendapat kelembaban. Sebagian besar adalah tanaman dasar hutan yang menyukai tempat-tempat lembap dan basah.

== Budidaya ==
Sejumlah rane dikenal baik sebagai tanaman hias, seperti

* ''S. apoda'' - "lumut ambon" atau "lumut papua"
* ''S. kraussiana -'' "rumput lumut"
* ''S. moellendorfii'' 
* ''S. erythropus -'' rane merah
* ''S. uncinata'' - rane biru
* ''S. lepidophylla'' - "resurrection plant"
* ''S. braunii''

== Referensi ==
{{reflist}}

{{Plant classification}}
{{Taxonbar|from=Q379743}}
[[Kategori:Tumbuhan paku]]
[[Kategori:Lycopodiophyta]]
[[Kategori:Selaginella| ]]
[[Kategori:Gulma]]
[[Kategori:Tanaman hias]]