Difference between revisions of "Eupatorium hyssopifolium"

Linnaeus

Sp. Pl. 2: 836. 1753.

Common names: Hyssopleaf thoroughwort
Treatment appears in FNA Volume 21. Treatment on page 468. Mentioned on page 464, 470, 473.
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|distribution=e North America.
 
|distribution=e North America.
 
|discussion=<p>Varieties 2 (2 in the flora).</p><!--
 
|discussion=<p>Varieties 2 (2 in the flora).</p><!--
--><p><i>Eupatorium hyssopifolium</i> includes both diploid and polyploid cytotypes and presents a complex situation taxonomically. The diploids are placed here in <i></i></i>var.<i><i> hyssopifolium</i>, which also includes polyploids and is characterized by relatively narrow leaves. Variety laciniatum has broader leaves and molecular data suggest that it arose through hybridization between <i></i></i>var.<i><i> hyssopifolium</i> and <i>E. serotinum</i>; the name E. torreyanum has been applied to plants of similar morphology, but these are hybrid derivatives of <i>E. serotinum</i> and <i>E. mohrii</i>. It has also been suggested that <i></i></i>var.<i><i> hyssopifolium</i> has hybridized with <i>E. album </i>var.<i> album</i> to form E. saltuense, and with diploids of <i>E. linearifolium</i> to form polyploid populations included here under <i>E. linearifolium</i>. <i>Eupatorium hyssopifolium</i> is characterized by a tendency for the leaves to be whorled, in 3s and 4s, and for axillary buds to produce leaves without expansion of shoots; the combination of whorled leaves and suppressed axillary shoots gives the nodes a somewhat tufted or verticillate appearance.</p>
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--><p><i>Eupatorium hyssopifolium</i> includes both diploid and polyploid cytotypes and presents a complex situation taxonomically. The diploids are placed here in <i></i>var.<i> hyssopifolium</i>, which also includes polyploids and is characterized by relatively narrow leaves. Variety laciniatum has broader leaves and molecular data suggest that it arose through hybridization between <i></i>var.<i> hyssopifolium</i> and <i>E. serotinum</i>; the name E. torreyanum has been applied to plants of similar morphology, but these are hybrid derivatives of <i>E. serotinum</i> and <i>E. mohrii</i>. It has also been suggested that <i></i>var.<i> hyssopifolium</i> has hybridized with <i>E. album </i>var.<i> album</i> to form E. saltuense, and with diploids of <i>E. linearifolium</i> to form polyploid populations included here under <i>E. linearifolium</i>. <i>Eupatorium hyssopifolium</i> is characterized by a tendency for the leaves to be whorled, in 3s and 4s, and for axillary buds to produce leaves without expansion of shoots; the combination of whorled leaves and suppressed axillary shoots gives the nodes a somewhat tufted or verticillate appearance.</p>
 
|tables=
 
|tables=
 
|references=
 
|references=
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-->{{#Taxon:
 
-->{{#Taxon:
 
name=Eupatorium hyssopifolium
 
name=Eupatorium hyssopifolium
|author=
 
 
|authority=Linnaeus
 
|authority=Linnaeus
 
|rank=species
 
|rank=species
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|publication year=1753
 
|publication year=1753
 
|special status=
 
|special status=
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/f6b125a955440c0872999024f038d74684f65921/coarse_grained_fna_xml/V19-20-21/V21_1167.xml
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|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/eaa6e58056e40c9ef614d8f47aea294977a1a5e9/coarse_grained_fna_xml/V19-20-21/V21_1167.xml
 
|tribe=Asteraceae tribe Eupatorieae
 
|tribe=Asteraceae tribe Eupatorieae
 
|genus=Eupatorium
 
|genus=Eupatorium

Revision as of 20:33, 16 December 2019

Perennials, 50–100+ cm. Stems (from short caudices or rhizomes) single, sparsely branched distally, pubescent throughout. Leaves usually opposite or whorled (distal sometimes alternate, spreading or horizontal); simple, sessile; blades 3-nerved from bases (laterals sometimes weak), lance-linear, lance-oblong, or linear, 20–60 × 2–15 mm (lengths mostly 6–40 times widths), bases cuneate, margins entire, laciniate-serrate, or serrate, apices acute, faces scabrous (at least abaxial). Heads in corymbiform arrays. Phyllaries 8–10 in 2–3 series, elliptic to oblong, 1.5–5 × 1–1.5 mm, apices obtuse to acute (not mucronate), abaxial faces pubescent throughout (more densely distally). Florets 5; corollas 3–3.5 mm. Cypselae 2–3 mm; pappi of 20–30 bristles 3.5–4 mm.

Discussion

Varieties 2 (2 in the flora).

Eupatorium hyssopifolium includes both diploid and polyploid cytotypes and presents a complex situation taxonomically. The diploids are placed here in var. hyssopifolium, which also includes polyploids and is characterized by relatively narrow leaves. Variety laciniatum has broader leaves and molecular data suggest that it arose through hybridization between var. hyssopifolium and E. serotinum; the name E. torreyanum has been applied to plants of similar morphology, but these are hybrid derivatives of E. serotinum and E. mohrii. It has also been suggested that var. hyssopifolium has hybridized with E. album var. album to form E. saltuense, and with diploids of E. linearifolium to form polyploid populations included here under E. linearifolium. Eupatorium hyssopifolium is characterized by a tendency for the leaves to be whorled, in 3s and 4s, and for axillary buds to produce leaves without expansion of shoots; the combination of whorled leaves and suppressed axillary shoots gives the nodes a somewhat tufted or verticillate appearance.

Selected References

None.

Key

1 Leaves mostly linear, 2–5 mm wide, margins usually entire or obscurely serrulate Eupatorium hyssopifolium var. hyssopifolium
1 Leaves mostly lance-linear to lanceolate, 5–15 mm wide, margins usually laciniately toothed Eupatorium hyssopifolium var. laciniatum