Polygonum shastense

Polygonum shastense
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Caryophyllales
Family:	Polygonaceae
Genus:	Polygonum
Species:	P. shastense
Binomial name
	Polygonum shastense; 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,^[1] where it grows in rocky and gravelly mountainous habitat up to 3300 meters (11,000 feet) elevation.^[2] It is most common in the Sierra Nevada.^[3] The species name refers to its occurrence on Mount Shasta in Shasta County, California.^[4]

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).^[5]

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.^[2] Leaves emerge curled slightly and folded in half lengthwise. Leaves have stipules which are widened into membranous ochrea wrapped around the leaf bases.^[5]

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.^[5]

References

^ Biota of North America Program 2014 county distribution map
^ ^2.0 ^2.1 Norman F. Weeden (1996). A Sierra Nevada Flora (4th ed.). Berkeley: Wilderness Press. ISBN 0-89997-204-7.
^ Calflora taxon report, University of California, Polygonum shastense A. Gray, Shasta knotweed
^ Brewer, William Henry. 1872. Proceedings of the American Academy of Arts and Sciences 8: 400, in footnote
^ ^5.0 ^5.1 ^5.2 Flora of North America, Polygonum shastense W. H. Brewer, 1872. Shasta knotweed

External links

Media related to Polygonum shastense at Wikimedia Commons

Jepson Manual Treatment – Polygonum shastense
Polygonum shastense – Calphotos Photo gallery, University of CaliforniaError: "Q7226471" is not a valid Wikidata entity ID.

[1] Biota of North America Program 2014 county distribution map

[Weeden-2] 2.0 ^2.1 Norman F. Weeden (1996). A Sierra Nevada Flora (4th ed.). Berkeley: Wilderness Press. ISBN 0-89997-204-7.

[3] Calflora taxon report, University of California, Polygonum shastense A. Gray, Shasta knotweed

[4] Brewer, William Henry. 1872. Proceedings of the American Academy of Arts and Sciences 8: 400, in footnote

[irene-5] 5.0 ^5.1 ^5.2 Flora of North America, Polygonum shastense W. H. Brewer, 1872. Shasta knotweed

[1]

[2]

[3]

[4]

[5]