Index- plants in this Family
Polygonaceae / Buckwheat
Pennsylvania Smartweed (Polygonum pensylvanicum)
Pennsylvania Smartweed is also known as Pink Knotweed and Pinkweed.

Plant Type: This is a herbaceous plant, it is a annual which can reach 122cm in height (48inches). The stem is jointed and a sheath extends up the stem from the joint enclosing the stem for a short distance. In this species the sheath is smooth. The upper stem is covered with tiny, stalked glands often referred to as sticky hairs.
Leaves: The leaves are alternate. Leaves can reach 15cm in length (6inches). Each leaf is entire.
Flowers: The flowers have 5 Regular Parts and are up to 0.3cm long (0.125 inches). They are pink. Blooms first appear in late spring and continue into mid fall. The flowers are in a dense spike like cluster about 1.3cm (.5") wide and often over 5cm (2") long.
Fruit: A two edged achene containing shinny black seeds.
Habitat: Moist open areas.
Range: Most of eastern North America.

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Like all members of the Buckwheat (Polygonaceae) family the flowers have no petals but three to six sepals which in the case of this plant are pink. A white form of this species is sometimes mentioned.(Rickett) Most species of smartweed will produce a burning sensation if tasted that is to say they have a bite or as the English once said a "smeorten" which may be where the term Smartweed comes from.(Erichsen- Brown)

Similar Species: Lady's Thumb or Spotted Ladysthumb (P. Persicaria) is a European species that has become naturalized throughout the US. It can reach 1m (3') in height and can be easily distinguished from P. Pensylvanicum by the fringed stem sheath and the dark spot present on the center of most leaves. Less similar is Dock-Leaved Smartweed also know as Curlytop Knotweed, Nodding or Pale Smartweed (P. Lapathifolium) can reach 2m (6') in height and has longer, slender flower spikes that droop and are white, pink or green.

There are about 30 other species of Polygonum in the Eastern US.

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More Info:  
The Search below may provide more information about this species. Some of URLs may have been used as a source for this page not otherwise cited. Most of the information not cited comes from multiple sources that can be found in the Books page. The USDA plant links are provided by: USDA, NRCS 1999. The PLANTS database ( National Plant Data Center, Baton Rouge, LA 70874-4490 USA. You can check species names at ITIS Advanced Search to see if they meet the current ITIS taxonomic criteria.

By: Newcomb, Lawrence and Illustrated by Morrison, Gordon. 1977, Little, Brown and Company, ISBN:0-316-60442-9

One of the best general guides to wildflowers of the North Eastern and North Central United States. Newcomb's key is an excellent, simple method for identifying plants. Newcomb has drawings for almost every plant mentioned that are excellent aids to identifying the species. Though only the more common plants are covered this is often the first book I pick up when trying to identify a wildflower.

Wildflo wers of Tennessee the Ohio Valley and the Southern Appalachians
By: Dennis Horn and Tavia Cathcart and Thomas E. Hemmerly and David Duhl. , ISBN:1551054280

This is perhaps the best of many field guides covering this region. Featuring 446 excellent color photographs (located with the text) and mentioning as similar to those illustrated are another 800 or so species for a total coverage of over 1,200 species. The start of each family section includes line drawings of some of the species showing important features. The text includes the usual description, bloom season, range, habitat and additionally includes information such as medical uses and lore and how the species was named. This is the official field guide of the Tennessee Native Plant Society.

Angiosperms / Flowering Plants
Dicots / Two Seed Leaves



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