Better Learning Through Botany

Exploring wetland ecology, scientific illustration, and native plants in the Pacific Northwest.

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    • What Are Wetland Praires
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Polygonaceae

Polygonaceae – Buckwheat

Comprising about 30 genera and 1,000 species, members of the Polygonaceae produce some well-known foods including buckwheat (Fagopyrum spp) and rhubarb (Rheum rhabarbarum), as well as some of North Americas most problematic invasive weeds – including species of Persicaria,[1] Rumex (ex. sheep’s sorrel), and Polygonum (ex. Japanese knotweed).[2]

Stems have swollen nodes with sheathing stipules (a papery membrane structure associated with petioles or nodes) called ocreas.[3] These sheathed ocreas give this family its name, where “Polygonaceae” broken down, “Poly” and “Genu,” in Latin translates to “many knees” in English referring to the nodes.[4] In our area, members of the Buckwheat family are annual and perennial herbs with simple leaves that are basal or alternate and cauline (emerge from the stem).[5]

Flowers are very small and radially symmetrical (actinomorphic), lacking petals, these plants have three to six connate sepals, with four to nine stamens arranged in two whorls.[6] The superior ovary consists of three united carpels that mature into a three angled/three winged dry achene that is wind dispersed.[7]

 Rumex salicifolius var. salicifolius – Willow Dock

RUSASpecies Code: RUSA

Habit: Leafy, clustered plant with erect open panicles.

Leaves: Alternately arranged, cauline leaves are 3 to 20 cm long with a short petiole. Leaf blades are linear to lanceolate with entire margins that can be flat or wavy. Leaves emerge oppositely from sheaths at swollen nodes along the stem.[8]

Stems:  Long, slender stalks begin as semi-decumbent (growing along the ground) and develop into erect stems reaching almost 90 centimeters in height. Stems produce axillary shoots below 1st-order inflorescences or at nodes near the center of the plant.[9]

Flowers: Inflorescence made up of a bracted cluster arrayed in several erect terminal panicles. Inflorescence panicles are 15 to 30 cm long, covered in dense bunches of many small greenish flowers.[10] Flowers have six persistent perianth lobes – outer three are inconspicuous, inner three are hardened, covering the fruit; Inner perianth lobes are 2 to 3 mm long, narrowly ovate to round, six stamens and three fringed stigmas.[11]

Fruits: Seeds are shiny, brown and round, generally 1.5 to 3 mm long.

Ecology: Facultative Wetland Species (FACW), a Hydrophyte that occurs mostly in sites that are wet in spring but dry by late summer and tolerates dryer areas.[12]

Notes: May be confused with the leaves of Curly dock (Rumex crispus), a related but invasive species from the Eastern Hemisphere. Rumex crispus has a red stalk with wider leaves than those of Willow Dock, with very wavy margins that turn brownish/red when dry.[13]

 

 

Polygonum douglasii – Douglas knotweed

 

 

 

[1] USDA Plants Database: <https://plants.usda.gov/core/profile?symbol=POCEL&gt;

[2] Peter Del Tredici, Wild Urban Plants of the Northeast, a Field Guide. Cornell University Press, NY. 2008.

[3] Pell, Susan. A Botanist’s Vocabulary. Timber Press, Portland, OR, 2016. 195

[4] Simpson, M. Plant Systematics 2nd ed. Academic Press, Burlington, MA. 2010. 309

[5] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001. 115

[6] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001. 115

[7] Elpel, T. J., Botany in a Day: The Patterns Method of Plant Identification. HOPS Press, 2004. 65.

[8] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001. 115

[9] Guard, J. (1995). Wetland Plants of Oregon and Washington. Lone Pine Publishing, Edmonton, Alberta. 104.

[10] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001.

[11] Gilkey, H. Handbook of Northwestern Plants, Revised Edition. Oregon State University Press; Corvallis, OR. 2001.

[12] USDA Plants Database: <https://plants.usda.gov/core/profile?symbol=RUSA&gt;

[13] Peter Del Tredici, Wild Urban Plants of the Northeast, a Field Guide. Cornell University Press, NY. 2008.

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Table of Contents

  • Menu
    • Home
    • Project Introduction
    • What Are Wetland Praires
    • Botanical Glossary
    • Illustrated Field Guide
      • Monocots
        • Forbs
          • Alismataceae
          • Amaryllidaceae
          • Asparagaceae
          • Iridaceae
          • Orchidaceae
          • Melanthiaceae – Death Camas
        • Grammanoids
          • Cyperaceae
          • Juncaceae
          • Poaceae
          • Typhaceae – Cattail Family
      • Dicots
        • Herbaceous
          • Apiaceae
          • Apocynaceae
          • Asteraceae
          • Boraginaceae
          • Brassicaceae
          • Campanulaceae
          • Caryophyllaceae
          • Fabaceae
          • Geraniaceae – Geranium Family
          • Lamiaceae – Mint Family
          • Malvaceae
          • Montiaceae
          • Onagraceae
          • Plantaginaceae
          • Polemoniaceae
          • Polygonaceae
          • Ranunculaceae
          • Rosaceae
          • Rubiaceae
          • Saxifragaceae – Saxifrag Family
          • Valerianaceae
        • Woody Plants
          • Oleaceae
          • Rosaceae
          • Salicaceae
      • Other
        • Equisetaceae
        • Isoetaceae
    • About the Author
    • Contact

Resources

  • Bridgham Lab at University of Oregon
  • Cal Flora
  • Cascadia Prairie Oak Partnership
  • City of Eugene Wetlands
  • City of Portland Weed ID Guide
  • Confederated Tribes of Grand Ronde
  • Current Plant Nomenclature
  • Institute for Applied Ecology
  • Ladybird Johnson Native Plant Center
  • Mount Pisgah Arboretum
  • Native American Ethnobotany Database
  • Native Community History of the Eugene Area
  • Native Plant Society Oregon
  • Oregon Flora Project
  • Oregon Flora Image Project
  • The Plant List
  • PNW Weed Identification Module
  • Practical Guidelines for Wetland Prairie Restoration
  • Roy Lab at University of Oregon
  • UO Museum of Natural and Cultural History
  • USDA Plants Database
  • University of Oregon Environmental Studies Program
  • Willow Creek Nature Conservancy Preserve
  • Willamette Resources & Education Network
  • Willamette Valley Native Plant Materials Network

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