View source for Dryas

{{Treatment/ID
|accepted_name=Dryas
|accepted_authority=Linnaeus
|publications={{Treatment/Publication
|title=Sp. Pl.
|place=1: 501. 1753
|year=1753
}}, {{Treatment/Publication
|title=Gen. Pl. ed.
|place=5, 220. 1754
|year=1754
}}
|common_names=Mountain-avens;dryade
|basionyms=
|synonyms=
|hierarchy=Rosaceae;Rosaceae subfam. Dryadoideae;Rosaceae tribe Dryadeae;Dryas
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Rosaceae]]</div><div class="higher-taxon"><small>subfamily</small>[[Rosaceae subfam. Dryadoideae]]</div><div class="higher-taxon"><small>tribe</small>[[Rosaceae tribe Dryadeae]]</div><div class="higher-taxon"><small>genus</small>[[Dryas]]</div></div>
|etymology=Greek Dryas, name for oak nymphs
|volume=Volume 9
|mention_page=page 73, 131, 327, 331, 343
|treatment_page=page 326
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="whole_organism arrangement or pubescence;whole_organism growth form;whole_organism architecture;whole_organism some measurement;whole_organism growth form"><b>Shrubs,</b> tufted or matted, scapose, 0.1–2.3 dm;</span> <span class="statement" id="st-d0_s1" data-properties="caudex length or size;caudex texture">caudices relatively long, woody.</span> <span class="statement" id="st-d0_s2" data-properties="stem quantity;stem architecture;stem architecture"><b>Stems </b>3+, branched, rooting freely;</span> <span class="statement" id="st-d0_s3" data-properties="">bark green in 1st year, reddish to brown in 2d year, often appearing blackish, peeling;</span> <span class="statement" id="st-d0_s4" data-properties="bark coloration;bark coloration;bark coloration;bark height or length or size;long-shoot presence">short and long-shoots absent;</span> <span class="statement" id="st-d0_s5" data-properties="branch architecture;branch orientation;branch height or length or size;branch pubescence">stoloniferous branches horizontal, relatively short, glabrous.</span> <span class="statement" id="st-d0_s6" data-properties="leaf duration;leaf architecture;basal leaflet atypical quantity;basal leaflet quantity"><b>Leaves </b>persistent, simple or (in D. drummondii) basal leaflets 1 (–2);</span> <span class="statement" id="st-d0_s7" data-properties="stipule duration;stipule shape;margin architecture or shape;margin shape">stipules persistent, narrowly lanceolate, margins usually entire, sometimes 1–2-toothed;</span> <span class="statement" id="st-d0_s8" data-properties="petiole presence">petiole present;</span> <span class="statement" id="st-d0_s9" data-properties="blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade atypical some measurement;blade some measurement;blade relief;blade architecture or arrangement or shape or vernation;margin prominence or shape;margin shape or vernation;margin shape;margin architecture or shape;margin architecture or shape;margin architecture or shape;abaxial surface pubescence;abaxial surface pubescence;adaxial surface pubescence;adaxial surface pubescence;adaxial surface pubescence">blade elliptic, lanceolate, linear, oblong, oblongelliptic, obovate, oval, or ovate, 0.2–3.9 (–4.6) cm, smooth to rugose or plicate, margins usually flat, sometimes revolute, crenate, dentate, serrate, or entire, abaxial surface tomentose or woolly, adaxial usually glabrous, sometimes tomentose or sparsely hairy on proximal portion of midvein.</span> <span class="statement" id="st-d0_s10" data-properties="inflorescence position or structure subtype;flower architecture or arrangement or growth form"><b>Inflorescences </b>terminal, flowers solitary;</span> <span class="statement" id="st-d0_s11" data-properties="bract presence">bracts absent;</span> <span class="statement" id="st-d0_s12" data-properties="bracteole presence">bracteoles absent.</span> <span class="statement" id="st-d0_s13" data-properties="pedicel presence"><b>Pedicels </b>present.</span> <span class="statement" id="st-d0_s14" data-properties="flower diameter"><b>Flowers </b>13–29 mm diam.;</span> <span class="statement" id="st-d0_s15" data-properties="hypanthium shape;hypanthium some measurement;exterior pubescence;exterior pubescence">hypanthium saucer-shaped, 3–15 mm, exterior villous, stipitate-glandular;</span> <span class="statement" id="st-d0_s16" data-properties="sepal quantity;sepal orientation;sepal shape;sepal shape;sepal shape">sepals 8–10, ascending to spreading, linear-oblong or linear-lanceolate to lanceolate, elliptic, or ovate;</span> <span class="statement" id="st-d0_s17" data-properties="petal atypical quantity;petal quantity;petal duration;petal duration;petal coloration;petal coloration;petal coloration;petal shape;petal shape;petal shape">petals 8–10 (–12), deciduous or persistent, usually white or cream, sometimes yellow, ovate to obovate, oblanceolate, or ovoid;</span> <span class="statement" id="st-d0_s18" data-properties="stamen quantity;stamen height or length or size">stamens 50–130, shorter than petals;</span> <span class="statement" id="st-d0_s19" data-properties="torus shape">torus hemispheric;</span> <span class="statement" id="st-d0_s20" data-properties="carpel quantity;carpel architecture;stigma position">carpels 60–150, sessile, stigmas lateral.</span> <span class="statement" id="st-d0_s21" data-properties="fruit shape;fruit some measurement;fruit architecture or pubescence or relief;achene arrangement;achene quantity;hair quantity;hair height or length or size;hair coloration"><b>Fruits </b>aggregated achenes, 20–40, linear to lanceolate, 0.8–3.5 mm, smooth with many short white hairs;</span> <span class="statement" id="st-d0_s22" data-properties="hypanthium duration">hypanthium persistent;</span> <span class="statement" id="st-d0_s23" data-properties="">sepals persistent, erect-ascending.</span> <span class="statement" id="st-d0_s24" data-properties="sepal duration;sepal orientation;x chromosome quantity">x = 9.</span><!--

-->{{Treatment/Body
|distribution=North America;Eurasia;arctic;boreal;and alpine regions
|discussion=<p>Species 15 (7 in the flora).</p><!--
--><p>Hybridization is common in Dryas (E. Hultén 1959b), often rendering specimen identification difficult when based on morphological features. Molecular evidence indicates that there are multiple morphologically similar species within the broad concept of D. octopetala (R. Elven et al., unpubl.). A study of amplified fragment length polymorphism (AFLP) markers found D. drummondii to be sister to all other species of the genus (I. Skrede et al. 2006). The taxonomy in the present treatment is based on that in the Pan-arctic Flora (R. Elven et al., http://nhm2.uio.no/paf/) and reflects the findings by Skrede et al. that AFLP markers support various proposals of B. A. Jurtzev (1984) and refute some of those by Hultén.</p><!--
--><p>Species of Dryas are among the important components of arctic and alpine tundra in terms of biomass (I. Skrede et al. 2006) and cover. Dryas has been placed in Dryadeae, which comprises four (Frankia association) actinorhizal genera, also including Cercocarpus, Chamaebatia, and Purshia (D. Potter et al. 2007). Dryas octopetala in the broad sense is characteristically a pioneer (T. T. Elkington 1971); it forms ectomycorrhizal associations with Hebeloma alpinum (J. Favre) Bruchet (Cortinariaceae, Agaricales), Cenococcum geophilum Fries (Ascomycetae, familial relationship unknown), and other fungi (M. Gardes and A. Dahlberg 1996). Nitrogen fixation occurs in root nodules of D. drummondii, D. integrifolia, and D. octopetala (in the broad sense) (D. B. Lawrence et al. 1967). The authors have observed root nodules on D. ajanensis subsp. beringensis. Soils in primary successional environments with D. drummondii have higher nitrogen and phosphorus, which facilitates growth of spruce seedlings (F. S. Chapin III et al. 1994). In late successional stages, D. drummondii is inhibited by alders by shading and from (possible) allelopathic effects (Chapin et al.).</p><!--
--><p>In the key and descriptions below, feathery hairs, referred to by some authors as “octopetala scales,” consist of relatively thick brown axes bearing delicate white hairs, appearing featherlike (E. Hultén 1959b). The brown 'axes' of Hultén are analogous to a feather rachis. Such hairs may be absent from rare individuals in species that normally have them. Normally glandular species may include rare eglandular individuals.</p>
|tables=
|references=
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Petals yellow, erect; leaf blades: bases usually cuneate (sometimes truncate or cordate); basal leaflets 1(–2); leaf surfaces tomentose; flowers nodding at flowering; filaments hairy.
|[[Dryas drummondii|Dryas drummondii]]
|-id=key-0-1
|1
|Petals usually white or cream, sometimes yellow, spreading; leaf blades: bases usually truncate or cordate, sometimes cuneate or rounded; basal leaflets 0; leaf abaxial surfaces tomentose to woolly, adaxial glabrous or glabrate, sometimes tomentose; flowers erect at flowering; filaments glabrous
|[[#key-0-2| > 2]]
|-id=key-0-2
|2
|Leaf blades: margins usually entire or dentate to crenate, sometimes serrate in proximal 1/2; (plants eglandular).
|[[Dryas integrifolia|Dryas integrifolia]]
|-id=key-0-2
|2
|Leaf blades: margins serrate to crenate or dentate (sometimes almost pinnatifid); (plants usually glandular, sometimes eglandular)
|[[#key-0-3| > 3]]
|-id=key-0-3
|3
|Feathery hairs usually present, especially abaxially on midveins
|[[#key-0-4| > 4]]
|-id=key-0-3
|3
|Feathery hairs usually absent, rarely 1+ feathery hairs abaxially on midveins in D. hookeriana and D. incisa
|[[#key-0-5| > 5]]
|-id=key-0-4
|4
|Feathery hairs and stipitate glands abundant along midveins abaxially; nw North America.
|[[Dryas ajanensis|Dryas ajanensis]]
|-id=key-0-4
|4
|Feathery hairs and stipitate glands scattered to rare along midveins abaxially; e Greenland.
|[[Dryas octopetala|Dryas octopetala]]
|-id=key-0-5
|5
|Leaf blades: sinuses of margins 45–60% to midvein, apices rounded to obtuse, surfaces smooth to rugose, plicate (midvein and lateral veins adaxially sunken into folds).
|[[Dryas alaskensis|Dryas alaskensis]]
|-id=key-0-5
|5
|Leaf blades: sinuses of margins 5–30% to midvein, apices acute to slightly obtuse, surfaces smooth to rugulose or slightly plicate, (margins strongly revolute to flat, only midvein ± obscured adaxially within fold)
|[[#key-0-6| > 6]]
|-id=key-0-6
|6
|Midveins and petioles not stipitate-glandular abaxially.
|[[Dryas incisa|Dryas incisa]]
|-id=key-0-6
|6
|Midveins and petioles stipitate-glandular abaxially.
|[[Dryas hookeriana|Dryas hookeriana]]
|}
</div></div><!--

-->{{#Taxon:
name=Dryas
|author=Joshua C. Springer;Bruce D. Parfitt†
|authority=Linnaeus
|rank=genus
|parent rank=tribe
|synonyms=
|basionyms=
|family=Rosaceae
|distribution=North America;Eurasia;arctic;boreal;and alpine regions
|reference=None
|publication title=Sp. Pl.;Gen. Pl. ed.
|publication year=1753;1754
|special status=
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-fine-grained-xml.git/src/84153f6d59a0a91d69695978a64cee7560374f8e/V9/V9_534.xml
|subfamily=Rosaceae subfam. Dryadoideae
|tribe=Rosaceae tribe Dryadeae
|genus=Dryas
|abaxial surface pubescence=woolly;tomentose
|achene arrangement=aggregated
|achene quantity=20;40
|adaxial surface pubescence=hairy;tomentose;glabrous
|bark coloration=blackish;reddish;brown
|bark height or length or size=short
|basal leaflet atypical quantity=1;2
|basal leaflet quantity=1
|blade architecture or arrangement or shape or vernation=plicate
|blade atypical some measurement=3.9cm;4.6cm
|blade relief=smooth;rugose
|blade shape=ovate;oval;ovate;oval;obovate;oblongelliptic;oblong;linear;lanceolate;elliptic
|blade some measurement=0.2cm;3.9cm
|bract presence=absent
|bracteole presence=absent
|branch architecture=stoloniferous
|branch height or length or size=short
|branch orientation=horizontal
|branch pubescence=glabrous
|carpel architecture=sessile
|carpel quantity=60;150
|caudex length or size=long
|caudex texture=woody
|exterior pubescence=stipitate-glandular;villous
|flower architecture or arrangement or growth form=solitary
|flower diameter=13mm;29mm
|fruit architecture or pubescence or relief=smooth
|fruit shape=linear;lanceolate
|fruit some measurement=0.8mm;3.5mm
|hair coloration=white
|hair height or length or size=short
|hair quantity=many
|hypanthium duration=persistent
|hypanthium shape=saucer--shaped
|hypanthium some measurement=3mm;15mm
|inflorescence position or structure subtype=terminal
|leaf architecture=simple
|leaf duration=persistent
|long-shoot presence=absent
|margin architecture or shape=entire;serrate;dentate;entire
|margin prominence or shape=flat
|margin shape=crenate;1-2-toothed
|margin shape or vernation=revolute
|pedicel presence=absent
|petal atypical quantity=10;12
|petal coloration=yellow;cream;white
|petal duration=persistent;deciduous
|petal quantity=8;10
|petal shape=ovate;obovate oblanceolate or ovoid
|petiole presence=absent
|sepal duration=persistent
|sepal orientation=erect-ascending;ascending;spreading
|sepal quantity=8;10
|sepal shape=linear-lanceolate;lanceolate elliptic or ovate
|stamen height or length or size=shorter
|stamen quantity=50;130
|stem architecture=rooting;branched
|stigma position=lateral
|stipule duration=persistent
|stipule shape=lanceolate
|torus shape=hemispheric
|whole_organism architecture=scapose
|whole_organism arrangement or pubescence=tufted
|whole_organism growth form=shrub;matted
|whole_organism some measurement=0.1dm;2.3dm
|x chromosome quantity=9
}}<!--

-->[[Category:Treatment]][[Category:Rosaceae tribe Dryadeae]]