Difference between revisions of "Picrothamnus"
Trans. Amer. Philos Soc., n. s. 7: 417. 1841.
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|distribution=w North America. | |distribution=w North America. | ||
|discussion=<p>Species 1.</p><!-- | |discussion=<p>Species 1.</p><!-- | ||
| − | --><p>Separation of Picrothamnus from Artemisia calls attention to differing views of generic circumscription within Anthemideae (see discussion under Artemisia). Distinguished by its spinescent branches and relatively large heads held among the leaves, Picrothamnus is among the more distinct of proposed segregates. The diffuse-porous woods (S. Carlquist 1966) correspond to the early spring-blooming phenology of the plants and provide an anatomic feature that helps to distinguish Picrothamnus from Artemisia.</p> | + | --><p>Separation of <i>Picrothamnus</i> from <i>Artemisia</i> calls attention to differing views of generic circumscription within Anthemideae (see discussion under <i>Artemisia</i>). Distinguished by its spinescent branches and relatively large heads held among the leaves, <i>Picrothamnus</i> is among the more distinct of proposed segregates. The diffuse-porous woods (S. Carlquist 1966) correspond to the early spring-blooming phenology of the plants and provide an anatomic feature that helps to distinguish <i>Picrothamnus</i> from <i>Artemisia</i>.</p> |
|tables= | |tables= | ||
|references= | |references= | ||
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|family=Asteraceae | |family=Asteraceae | ||
|illustrator=John Myers | |illustrator=John Myers | ||
| + | |illustration copyright=Flora of North America Association | ||
|distribution=w North America. | |distribution=w North America. | ||
|reference=None | |reference=None | ||
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|publication year=1841 | |publication year=1841 | ||
|special status= | |special status= | ||
| − | |source xml=https:// | + | |source xml=https://bitbucket.org/aafc-mbb/fna-data-curation/src/2e0870ddd59836b60bcf96646a41e87ea5a5943a/coarse_grained_fna_xml/V19-20-21/V19_833.xml |
|tribe=Asteraceae tribe Anthemideae | |tribe=Asteraceae tribe Anthemideae | ||
|genus=Picrothamnus | |genus=Picrothamnus | ||
Latest revision as of 19:57, 5 November 2020
Subshrubs or shrubs, 5–30(–50) cm (strongly aromatic). Stems 1–10+, usually erect, diffusely branched from bases and throughout (some laterals persistent, forming thorns), villous to arachnose (hairs medifixed). Leaves mostly cauline; alternate; petiolate or sessile; blades ± orbiculate to flabellate, simple or 1–2-pedately lobed (lobes orbiculate to spatulate or linear), ultimate margins entire, faces ± villous and gland-dotted. Heads disciform, usually (2–12+) in ± leafy, racemiform to spiciform arrays, rarely borne singly. Involucres ± obconic, 2–3(–5) mm diam. Phyllaries persistent, 5–8 in ± 2 series, distinct, ± obovate, subequal, margins and apices (hyaline) narrowly scarious. Receptacles convex (glabrous), epaleate. Ray florets 0 (peripheral pistillate florets 2–8; corollas pale yellow, ± filiform, ± villous). Disc florets 5–13(–15), functionally staminate; corollas pale yellow (± villous), tubes ± cylindric, throats campanulate, lobes 5, ± deltate. Cypselae (brown) obovoid to ellipsoid, ribs 0, faces ± villous and obscurely nerved (pericarps without myxogenic cells or resin sacs); pappi 0. x = 9.
Distribution
w North America.
Discussion
Species 1.
Separation of Picrothamnus from Artemisia calls attention to differing views of generic circumscription within Anthemideae (see discussion under Artemisia). Distinguished by its spinescent branches and relatively large heads held among the leaves, Picrothamnus is among the more distinct of proposed segregates. The diffuse-porous woods (S. Carlquist 1966) correspond to the early spring-blooming phenology of the plants and provide an anatomic feature that helps to distinguish Picrothamnus from Artemisia.
Selected References
None.