Polygonum shastense
{{Short description|Species of flowering plant}}
{{Speciesbox
|image = Polygonum shastense pink branch.jpg
|genus = Polygonum
|species = shastense
|authority = W.H.Brewer 1872
}}
Polygonum shastense is a species of flowering plant in the knotweed family known by the common name Shasta knotweed. It is native to sections of southwestern Oregon, northwestern Nevada, and northern and central California,[http://bonap.net/MapGallery/County/Polygonum%20shastense.png Biota of North America Program 2014 county distribution map] where it grows in rocky and gravelly mountainous habitat up to 3300 meters (11,000 feet) elevation. It is most common in the Sierra Nevada.[http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=6774 Calflora taxon report, University of California, Polygonum shastense A. Gray, Shasta knotweed ] The species name refers to its occurrence on Mount Shasta in Shasta County, California.[https://www.biodiversitylibrary.org/page/3071714#page/406/mode/1up Brewer, William Henry. 1872. Proceedings of the American Academy of Arts and Sciences 8: 400, in footnote]
Description
Polygonum shastense is a rather elegant small perennial shrub producing branching tough, gnarled brown stems reaching a maximum length of 40 centimeters (16 inches), growing prostrate along the ground or somewhat upright. The bases of old plants can be wide, woody and gray (see image above left).
The leaves lining the slender but rough stems are uniform in size and distribution, not clustered or reduced in size near stem tips. They are lance-shaped with two parallel veins separating three raised areas on the upper surface (see closeup at left), each leaf measuring 5 to 8 millimeters (0.20–0.32 inches) long.{{cite book |author=Norman F. Weeden |title=A Sierra Nevada Flora |year=1996 |edition=4th |publisher=Wilderness Press |location=Berkeley |isbn=0-89997-204-7 |url-access=registration |url=https://archive.org/details/sierranevadaflor00weed }} Leaves emerge curled slightly and folded in half lengthwise. Leaves have stipules which are widened into membranous ochrea wrapped around the leaf bases.
Flowers occur in clusters in upper leaf axils. Each is just under a centimeter wide and has five rounded petals, either white with a green stripe or pink with a dark stripe. There are 5–8 stamens and a triangular pistil with a 3-lobed style. Plants may have either all white, all pink, or a mixture of flower colors.[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250060761 Flora of North America, Polygonum shastense W. H. Brewer, 1872. Shasta knotweed ]
Image:Polygonum shastense jeans 2-vein leaf.jpg
Image:Polygonum shastense white bonsai.jpg
Image:Polygonum shastense held white.jpg
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References
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External links
{{commons-inline|Polygonum shastense|Polygonum shastense}}
- [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?5936,6248,6290 Jepson Manual Treatment – Polygonum shastense]
- [http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-taxon=Polygonum+shastense Polygonum shastense – Calphotos Photo gallery, University of California]
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Category:Flora of the Sierra Nevada (United States)
Category:Endemic flora of the United States
Category:Plants described in 1872