View source for Adiantum

{{Treatment/ID
|accepted_name=Adiantum
|accepted_authority=Linnaeus
|publications={{Treatment/Publication
|title=Sp. Pl.
|place=2: 1094. 1753; Gen. Pl. ed 5, 485. 1754
|year=1754
}}
|common_names=Maidenhair fern
|basionyms=
|synonyms=
|hierarchy=Pteridaceae;Adiantum
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Pteridaceae]]</div><div class="higher-taxon"><small>genus</small>[[Adiantum]]</div></div>
|etymology=Greek adiantos, unwetted, for the glabrous leaves, which shed raindrops
|volume=Volume 2
|mention_page=
|treatment_page=
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="whole_organism growth form or habitat;whole_organism growth form or habitat;whole_organism growth form"><b>Plants </b>terrestrial or on rock.</span> <span class="statement" id="st-d0_s1" data-properties="stem height or length or size;stem orientation;stem orientation;stem architecture"><b>Stems </b>short to long-creeping or suberect, branched;</span> <span class="statement" id="st-d0_s2" data-properties="scale coloration;scale coloration;scale coloration;scale shape;margin architecture;margin architecture;margin architecture;margin architecture;margin architecture">scales deep tawny yellow to dark reddish-brown [black], concolored or bicolored, linear-lanceolate to lanceolate, margins entire, erose-ciliate, or minutely dentate.</span> <span class="statement" id="st-d0_s3" data-properties="leaf architecture;leaf growth form;leaf arrangement;leaf some measurement"><b>Leaves </b>monomorphic to somewhat dimorphic, densely clustered to closely spaced [distant], 15–110 cm.</span> <span class="statement" id="st-d0_s4" data-properties="petiole coloration;petiole pubescence;petiole pubescence;petiole pubescence;petiole pubescence;petiole pubescence;groove quantity"><b>Petiole </b>chestnut-brown to dark purple or blackish, with single groove adaxially, glabrous, hispid, or strigose, with 1 or 2 vascular-bundles.</span> <span class="statement" id="st-d0_s5" data-properties="blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade architecture or shape;blade texture;surface pubescence;surface reflectance;surface reflectance;surface coloration or pubescence or relief"><b>Blade </b>lanceolate, ovate, trowel-shaped, or fan-shaped, 1–4 (–9) -pinnate proximally, membranaceous to papery, both surfaces commonly glabrous (2 species with scattered hairs), adaxially dull or shiny, not striate;</span> <span class="statement" id="st-d0_s6" data-properties="rachis course;rachis course">rachis straight or flexuous.</span> <span class="statement" id="st-d0_s7" data-properties="ultimate segment architecture;ultimate segment shape;ultimate segment shape;ultimate segment shape;ultimate segment shape;ultimate segment shape;ultimate segment shape;ultimate segment width"><b>Ultimate </b>segments subsessile to short-stalked (stalks terminating in cupulelike swelling at base of pinna in A. tenerum), round, fan-shaped, rhombic, or oblong, 3–29 mm wide;</span> <span class="statement" id="st-d0_s8" data-properties="base shape;base fusion">base truncate to cuneate, free from costa;</span> <span class="statement" id="st-d0_s9" data-properties="stalk coloration;stalk reflectance">stalk dark, often lustrous;</span> <span class="statement" id="st-d0_s10" data-properties="segment reproduction;marginal lobe orientation">fertile segments with marginal lobes recurved to form false indusia.</span> <span class="statement" id="st-d0_s11" data-properties="vein prominence;vein fusion;vein architecture or shape;vein arrangement"><b>Veins </b>of ultimate segments conspicuous, free, ± dichotomously forking near base and well above segment base [anastomosing in a few tropical species], parallel distally.</span> <span class="statement" id="st-d0_s12" data-properties="false indusium coloration;false indusium size or width;false indusium width;false indusium position"><b>False </b>indusia light gray-green or brown to dark-brown, narrow, 0.6–1 mm wide, marginal, concealing sporangia until sporangia dehisce.</span> <span class="statement" id="st-d0_s13" data-properties="sporangium position;abaxial surface presence"><b>Sporangia </b>submarginal, borne along or sometimes also between veins on abaxial surface of false indusium, paraphyses and glands absent.</span> <span class="statement" id="st-d0_s14" data-properties="spore coloration;spore coloration;spore shape;spore architecture;spore relief"><b>Spores </b>yellow or yellowish-brown, tetrahedral-globose, trilete, rugulate to rugose or tuberculate, equatorial-ridge absent.</span> <span class="statement" id="st-d0_s15" data-properties="equatorial-ridge presence;x chromosome quantity;x chromosome quantity">x = 29, 30.</span><!--

-->{{Treatment/Body
|distribution=Nearly worldwide except at latitudes greater than 60°
|discussion=<p>Most diverse in Andean South America, Adiantum is primarily a tropical genus; of the nine species occurring in the flora, A. melanoleucum, A. tenerum, and A. tricholepis are strictly subtropical. Adiantum hispidulum occurs only as an escape from cultivation. The genus is absent from dry areas in the interior of the continent.</p><!--
--><p>Adiantum is a very clearly circumscribed genus of ferns, the character state "sporangia borne on abaxial surface of false indusium" being both necessary and sufficient to define it. Within this large and widespread genus, however, species relationships are mostly unknown. An evolutionary classification of the group is indeed much needed (R. M. Tryon and A. F. Tryon 1982).</p><!--
--><p>Species ca. 150–200 (9 in the flora).</p>
|tables=
|references={{Treatment/Reference
|id=fernald1950a
|text=Fernald, M. L. 1950b. Adiantum capillus-veneris in the United States. Rhodora 52: 201--208.
}}{{Treatment/Reference
|id=paris1988a
|text=Paris, C. A. and M. D. Windham. 1988. A biosystematic investigation of the Adiantum pedatum complex in eastern North America. Syst. Bot. 13: 240--255.
}}{{Treatment/Reference
|id=paris1991a
|text=Paris, C. A. 1991. Adiantum viridimontanum, a new maidenhair fern in eastern North America. Rhodora 93: 105--122.
}}{{Treatment/Reference
|id=wagner1956a
|text=Wagner, W. H. Jr. 1956. A natural hybrid, × Adiantum tracyi C. C. Hall. Madroño 13: 195--205.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Segments at middle of penultimate divisions of blades ± fan-shaped, rhombic, transversely oblong, or nearly round, about as long as broad.
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Segments at middle of penultimate divisions of blades ± oblong or long-triangular, at least 2 times as long as broad (rarely, reniform).
|[[#key-0-5| > 5]]
|-id=key-0-2
|2
|Dark color of stalks extending into base of ultimate segments.
|[[Adiantum capillus-veneris|Adiantum capillus-veneris]]
|-id=key-0-2
|2
|Dark color of stalks ending ± abruptly at base of ultimate segments.
|[[#key-0-3| > 3]]
|-id=key-0-3
|3
|Segment stalks terminating in small, cupulelike swelling at base of ultimate segments.
|[[Adiantum tenerum|Adiantum tenerum]]
|-id=key-0-3
|3
|Segment stalks not terminating in small, cupulelike swelling at base of ultimate segments.
|[[#key-0-4| > 4]]
|-id=key-0-4
|4
|Ultimate segments glabrous.
|[[Adiantum jordanii|Adiantum jordanii]]
|-id=key-0-4
|4
|Ultimate segments hirsute.
|[[Adiantum tricholepis|Adiantum tricholepis]]
|-id=key-0-5
|5
|Rachises hispid or strigose; blades pinnate (occasionally pseudopedate in Adiantum hispidulum).
|[[#key-0-6| > 6]]
|-id=key-0-5
|5
|Rachises glabrous; blades pseudopedate.
|[[#key-0-7| > 7]]
|-id=key-0-6
|6
|Ultimate segments with scattered multicelled hairs; rachises hispid; false indusia ± round.
|[[Adiantum hispidulum|Adiantum hispidulum]]
|-id=key-0-6
|6
|Ultimate segments glabrous; rachises strigose; false indusia crescent-shaped.
|[[Adiantum melanoleucum|Adiantum melanoleucum]]
|-id=key-0-7
|7
|Segments at middle of penultimate divisions of blades ± oblong; leaves lax-arching, blades fan-shaped.
|[[#key-0-8| > 8]]
|-id=key-0-7
|7
|Segments at middle of penultimate divisions ± long-triangular or reniform; leaves arching to stiffly erect, blades fan-shaped to funnel-shaped.
|[[#key-0-9| > 9]]
|-id=key-0-8
|8
|Segments at middle of penultimate divisions of blades generally less than 3.2 times as long as broad, apices with rounded, crenulate or crenate-denticulate lobes, lobes separated by shallow sinuses 0.1–2(–3.7) mm, segment stalks ca. 0.6–0.9 mm.
|[[Adiantum pedatum|Adiantum pedatum]]
|-id=key-0-8
|8
|Segments at middle of penultimate divisions usually more than 3.2 times as long as broad, apices with sharply denticulate, angular lobes, lobes separated by deep sinuses 0.6–4 mm, segment stalks to 0.6 mm.
|[[Adiantum aleuticum|Adiantum aleuticum]]
|-id=key-0-9
|9
|Central ultimate segments on stalks less than 0.9 mm; false indusia mostly less than 3.5 mm.
|[[Adiantum aleuticum|Adiantum aleuticum]]
|-id=key-0-9
|9
|Central ultimate segments on stalks generally greater than 0.9 mm; false indusia mostly exceeding 3.5 mm.
|[[Adiantum viridimontanum|Adiantum viridimontanum]]
|}
</div></div><!--

-->{{#Taxon:
name=Adiantum
|author=Cathy A. Paris
|authority=Linnaeus
|rank=genus
|parent rank=family
|synonyms=
|basionyms=
|family=Pteridaceae
|distribution=Nearly worldwide except at latitudes greater than 60°
|reference=fernald1950a;paris1988a;paris1991a;wagner1956a
|publication title=Sp. Pl.
|publication year=1754
|special status=
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-fine-grained-xml.git/src/84153f6d59a0a91d69695978a64cee7560374f8e/V2/V2_455.xml
|genus=Adiantum
|abaxial surface presence=absent
|base fusion=free
|base shape=truncate;cuneate
|blade architecture or shape=1-4(-9)-pinnate
|blade shape=fan--shaped;trowel--shaped;fan--shaped;trowel--shaped;ovate;lanceolate
|blade texture=membranaceous;papery
|equatorial-ridge presence=absent
|false indusium coloration=brown;dark-brown
|false indusium position=marginal
|false indusium size or width=narrow
|false indusium width=0.6mm;1mm
|groove quantity=single
|leaf architecture=monomorphic
|leaf arrangement=densely clustered;closely spaced
|leaf growth form=dimorphic
|leaf some measurement=15cm;110cm
|margin architecture=dentate;erose-ciliate;dentate;erose-ciliate;entire
|marginal lobe orientation=recurved
|petiole coloration=chestnut-brown;dark purple or blackish
|petiole pubescence=strigose;hispid;strigose;hispid;glabrous
|rachis course=flexuous;straight
|scale coloration=tawny yellow;dark reddish-brown concolored or bicolored
|scale shape=linear-lanceolate;lanceolate
|segment reproduction=fertile
|sporangium position=submarginal
|spore architecture=trilete
|spore coloration=yellowish-brown;yellow
|spore relief=rugulate;rugose or tuberculate
|spore shape=tetrahedral-globose
|stalk coloration=dark
|stalk reflectance=lustrous
|stem architecture=branched
|stem height or length or size=short
|stem orientation=suberect;long-creeping
|surface coloration or pubescence or relief=not striate
|surface pubescence=glabrous
|surface reflectance=shiny;dull
|ultimate segment architecture=subsessile;short-stalked
|ultimate segment shape=oblong;rhombic;oblong;rhombic;fan--shaped;round
|ultimate segment width=3mm;29mm
|vein architecture or shape=forking
|vein arrangement=parallel
|vein fusion=free
|vein prominence=conspicuous
|whole_organism growth form=plant
|whole_organism growth form or habitat=on rock;terrestrial
|x chromosome quantity=30;29
}}<!--

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