View source for Dicranum howellii

{{Treatment/ID
|accepted_name=Dicranum howellii
|accepted_authority=Renauld & Cardot
|publications={{Treatment/Publication
|title=Rev. Bryol.
|place=15: 70. 1888,
}}
|basionyms=
|synonyms=
|hierarchy=Dicranaceae;Dicranum;Dicranum howellii
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Dicranaceae]]</div><div class="higher-taxon"><small>genus</small>[[Dicranum]]</div><div class="higher-taxon"><small>species</small>[[Dicranum howellii]]</div></div>
|volume=Volume 27
|mention_page=page 399, 404
|treatment_page=page 403
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="whole_organism coloration;whole_organism reflectance;whole_organism growth form;tuft architecture or fragility;tuft density"><b>Plants </b>in loose to dense tufts, green to yellowish green, glossy.</span> <span class="statement" id="st-d0_s1" data-properties="stem some measurement;stem pubescence;rhizoid coloration"><b>Stems </b>2–8 cm, densely tomentose with white to reddish-brown rhizoids.</span> <span class="statement" id="st-d0_s2" data-properties="leaf arrangement;leaf course;leaf orientation;leaf shape;leaf architecture or pubescence or relief;leaf atypical length;leaf atypical length;leaf length;leaf width;leaf shape;leaf shape;leaf shape;leaf shape;apex shape"><b>Leaves </b>falcate-secund to straight and erect, sometimes slightly crisped, smooth, (5–) 8–10 (–12) × 0.8–1.5 mm, concave proximally, keeled or tubulose above, lanceolate, apex acute;</span> <span class="statement" id="st-d0_s3" data-properties="margin architecture or shape;margin architecture or shape">margins strongly serrate in the distal part, entire proximally;</span> <span class="statement" id="st-d0_s4" data-properties="lamina architecture">laminae 1-stratose;</span> <span class="statement" id="st-d0_s5" data-properties="costa architecture;costa quantity;base quantity;base quantity;ridge shape;ridge architecture or pubescence or relief;ridge width;abaxial surface width;leaf position;row quantity;adaxial epidermal layer variability;abaxial layer architecture;cell quantity;cell size">costa ending before apex to shortly excurrent, 1/12–1/5 the width of the leaves at base, with 2, rarely 4, toothed ridges on the abaxial surface extending from about the leaf middle nearly to the apex, rarely almost smooth, with a row of guide cells, two thin stereid bands, adaxial epidermal layer of cells not differentiated, the abaxial layer interrupted by several enlarged cells that form part of the abaxial ridge, not extending to the apices;</span> <span class="statement" id="st-d0_s6" data-properties="between cells cell-wall pubescence or shape">cell-walls between lamina cells not bulging;</span> <span class="statement" id="st-d0_s7" data-properties="">leaf cells smooth;</span> <span class="statement" id="st-d0_s8" data-properties="leaf cell architecture or pubescence or relief;cell architecture;cell variability">alar cells 2-stratose, well-differentiated, sometimes extending to costa;</span> <span class="statement" id="st-d0_s9" data-properties="proximal laminal cell shape;proximal laminal cell relief;proximal laminal cell atypical length;proximal laminal cell atypical length;proximal laminal cell length;proximal laminal cell atypical width;proximal laminal cell atypical width;proximal laminal cell width">proximal laminal cells linear-rectangular, pitted, (52–) 65–105 (–120) × (10–) 12–18 (–22) µm; distal laminal cells shorter, sinuose, pitted, (42–) 54–90 (–108) µm × (10–) 12–14 (–16) µm. <b>Sexual</b> condition pseudomonoicous or dioicous;</span> <span class="statement" id="st-d0_s10" data-properties="distal laminal cell height or length or size;distal laminal cell architecture;distal laminal cell relief;distal laminal cell atypical length;distal laminal cell atypical length;distal laminal cell length;distal laminal cell atypical width;distal laminal cell atypical width;distal laminal cell width;distal laminal cell reproduction;distal laminal cell reproduction;distal laminal cell reproduction;distal laminal cell height;rhizoid reproduction;plant reproduction;plant reproduction;tuft arrangement">dwarf males on rhizoids of female plants or male plants as large as females and growing intermixed or in ± separate tufts;</span> <span class="statement" id="st-d0_s11" data-properties="perichaetial leaf shape;perichaetial leaf architecture or shape">perichaetial leaves gradually acuminate, not or partially convolute-sheathing.</span> <span class="statement" id="st-d0_s12" data-properties="seta some measurement;seta architecture or arrangement or growth form;seta quantity;seta coloration"><b>Seta </b>1.5–4 cm, solitary, sometimes 2 per perichaetium, yellow to reddish-brown.</span> <span class="statement" id="st-d0_s13" data-properties="capsule some measurement;capsule course or shape;capsule orientation;capsule pubescence;capsule coloration"><b>Capsule </b>2–3.8 mm, arcuate, inclined to horizontal, smooth to striate when dry, yellow to dark reddish-brown;</span> <span class="statement" id="st-d0_s14" data-properties="operculum some measurement">operculum 2–3.8 mm.</span> <span class="statement" id="st-d0_s15" data-properties="spore some measurement"><b>Spores </b>18–26 µm.</span><!--

-->{{Treatment/Body
|phenology=Capsules mature spring.
|habitat=Soil, humus, humus over rock, rotting logs and stumps, tree trunks and bases of trees, sometimes in bogs
|elevation=20-600 m
|distribution=B.C.;Alaska;Calif.;Idaho;Mont.;Oreg.;Wash.
|discussion=<p>Dicranum howellii occurrs only in the northwestern part of North America. It is closely related to the common and nearly ubiquitous D. scoparium. The shape of the interior perichaetial leaves is the most reliable way to distinguish the two. Gradually acuminate perichaetial leaves that loosely surround the seta are characteristic of D. howellii. Dicranum scoparium has abruptly acuminate exterior perichaetial leaves, interior ones that are abruptly acuminateto blunt at the apex and are convolute-sheathing around the seta. The interior perichaetial leaves of D. howellii are also longer and narrower than those of the D. scoparium. Other less significant features of D. howellii are the consistently glossy, long leaves, mostly 8–10 mm, with long distal cells, averaging 54–90 µm, and the common occurrence of only two, rarely four, serrated ridges on the abaxial surface of the costae. Dicranum scoparium by comparison has glossy to sometimes dull leaves that are often shorter, mostly 5–8.5 mm, with shorter distal cells, averaging 27–43 µm, and the costae usually have four, rarely two, serrated ridges on the abaxial surface. The perichaetial leaves are undoubtedly the most important feature separating the two species, as well as being the easiest to observe. Eastern North American plants of D. scoparium all have the abruptly acuminate perichaetial leaves that are characteristic of the species, as do plants elsewhere in the world. The perichaetial leaf character was one reason D. howellii was believed to be a distinct species by F. Renauld and J. Cardot (1889, plate 12B) who first illustrated that character and this remains the most significant reason for maintaining it as a distinct species.</p>
|tables=
|references=
}}<!--

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-->{{#Taxon:
name=Dicranum howellii
|authority=Renauld & Cardot
|rank=species
|parent rank=genus
|synonyms=
|basionyms=
|family=Dicranaceae
|phenology=Capsules mature spring.
|habitat=Soil, humus, humus over rock, rotting logs and stumps, tree trunks and bases of trees, sometimes in bogs
|elevation=20-600 m
|distribution=B.C.;Alaska;Calif.;Idaho;Mont.;Oreg.;Wash.
|reference=None
|publication title=Rev. Bryol.
|publication year=
|special status=
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-fine-grained-xml.git/src/84153f6d59a0a91d69695978a64cee7560374f8e/V27/V27_569.xml
|genus=Dicranum
|species=Dicranum howellii
|abaxial layer architecture=interrupted
|abaxial surface width=extending
|adaxial epidermal layer variability=not differentiated
|apex shape=acute
|base quantity=4;2
|between cells cell-wall pubescence or shape=not bulging
|capsule coloration=yellow;dark reddish-brown
|capsule course or shape=arcuate
|capsule orientation=inclined;horizontal
|capsule pubescence=smooth;striate
|capsule some measurement=2mm;3.8mm
|cell architecture=2-stratose
|cell quantity=several
|cell size=enlarged
|cell variability=well-differentiated
|costa architecture=excurrent
|costa quantity=1/12;1/5
|distal laminal cell architecture=sinuose
|distal laminal cell atypical length=90um;108um
|distal laminal cell atypical width=14um;16um
|distal laminal cell height=dwarf
|distal laminal cell height or length or size=shorter
|distal laminal cell length=54um;90um
|distal laminal cell relief=pitted
|distal laminal cell reproduction=dioicous;pseudomonoicous;sexual
|distal laminal cell width=12um;14um
|lamina architecture=1-stratose
|leaf architecture or pubescence or relief=smooth
|leaf arrangement=falcate-secund
|leaf atypical length=10mm;12mm
|leaf cell architecture or pubescence or relief=smooth
|leaf course=straight
|leaf length=8mm;10mm
|leaf orientation=erect
|leaf position=middle
|leaf shape=lanceolate;tubulose;keeled;concave;crisped
|leaf width=0.8mm;1.5mm
|margin architecture or shape=entire;serrate
|operculum some measurement=2mm;3.8mm
|perichaetial leaf architecture or shape=convolute-sheathing
|perichaetial leaf shape=acuminate
|plant reproduction=male;female
|proximal laminal cell atypical length=105um;120um
|proximal laminal cell atypical width=18um;22um
|proximal laminal cell length=65um;105um
|proximal laminal cell relief=pitted
|proximal laminal cell shape=linear-rectangular
|proximal laminal cell width=12um;18um
|rhizoid coloration=white;reddish-brown
|rhizoid reproduction=male
|ridge architecture or pubescence or relief=smooth
|ridge shape=toothed
|ridge width=thin
|row quantity=2
|seta architecture or arrangement or growth form=solitary
|seta coloration=yellow;reddish-brown
|seta quantity=2
|seta some measurement=1.5cm;4cm
|spore some measurement=18um;26um
|stem pubescence=tomentose
|stem some measurement=2cm;8cm
|tuft architecture or fragility=loose
|tuft arrangement=separate
|tuft density=dense
|whole_organism coloration=green;yellowish green
|whole_organism growth form=plant
|whole_organism reflectance=glossy
}}<!--

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