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Useful Temperate Plants

Polygonum douglasii

Greene.

Polygonaceae


The Temperate Database is in the process of being updated, with new records being added and old ones being checked and brought up to date where necessary. This record has not yet been checked and updated.

+ Synonyms

Common Name: Knotweed

No Image.

General Information

Polygonum douglasii is a Annual up to 0.30 metres tall.
It has edible uses.

Known Hazards

Although no specific mention has been made for this species, there have been reports that some members of this genus can cause photosensitivity in susceptible people.
Many species also contain oxalic acid (the distinctive lemony flavour of sorrel) - whilst not toxic this substance can bind up other minerals making them unavailable to the body and leading to mineral deficiency. Having said that, a number of common foods such as sorrel and rhubarb contain oxalic acid and the leaves of most members of this genus are nutritious and beneficial to eat in moderate quantities. Cooking the leaves will reduce their content of oxalic acid. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet since it can aggravate their condition[
238
Title
Encyclopaedia of Herbs and their Uses.
Publication
 
Author
Bown. D.
Publisher
Dorling Kindersley, London.
Year
1995
ISBN
0-7513-020-31
Description
A very well presented and informative book on herbs from around the globe. Plenty in it for both the casual reader and the serious student. Just one main quibble is the silly way of having two separate entries for each plant.
].

Botanical References

43
Title
Gray's Manual of Botany.Eighth Edition
Publication
 
Author
Fernald. M. L.
Publisher
American Book Co.; New York
Year
1950
ISBN
0442222505
Description
A bit dated but a good and concise flora of the eastern part of N. America.
,
60
Title
Vascular Plants of the Pacific Northwest.
Publication
 
Author
Hitchcock. C. L.
Publisher
University of Washington Press
Year
1955
ISBN
-
Description
A standard flora for Western N. America with lots of information on habitat etc. Five large volumes, it is not for the casual reader.
,
235
Title
An Illustrated Flora of the Northern United States and Canada
Publication
 
Author
Britton. N. L. Brown. A.
Publisher
Dover Publications. New York.
Year
1970
ISBN
0-486-22642-5
Description
Reprint of a 1913 Flora, but still a very useful book.

Range

N. America - Northwest Territory to British Columbia, south to Vermont, New Mexico and Oklahoma.

Habitat

Rocky slopes and dry soils all over N. America[
43
Title
Gray's Manual of Botany.Eighth Edition
Publication
 
Author
Fernald. M. L.
Publisher
American Book Co.; New York
Year
1950
ISBN
0442222505
Description
A bit dated but a good and concise flora of the eastern part of N. America.
,
60
Title
Vascular Plants of the Pacific Northwest.
Publication
 
Author
Hitchcock. C. L.
Publisher
University of Washington Press
Year
1955
ISBN
-
Description
A standard flora for Western N. America with lots of information on habitat etc. Five large volumes, it is not for the casual reader.
].

Properties

Edibility Rating *  *
HabitAnnual
Height0.30 m
PollinatorsInsects
Cultivation StatusWild

Cultivation Details

We have very little information on this species and do not know if it is hardy in Britain, though judging by its native range it should succeed outdoors in most parts of the country. The following notes are based on the general needs of the genus.
Succeeds in an ordinary garden soil[
1
Title
RHS Dictionary of Plants plus Supplement. 1956
Publication
 
Author
F. Chittendon.
Publisher
Oxford University Press
Year
1951
ISBN
-
Description
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [200]).
] but prefers a moisture retentive not too fertile soil in sun or part shade[
200
Title
The New RHS Dictionary of Gardening. 1992.
Publication
 
Author
Huxley. A.
Publisher
MacMillan Press
Year
1992
ISBN
0-333-47494-5
Description
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
]. Repays generous treatment[
1
Title
RHS Dictionary of Plants plus Supplement. 1956
Publication
 
Author
F. Chittendon.
Publisher
Oxford University Press
Year
1951
ISBN
-
Description
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [200]).
].
Plants seem to be immune to the predations of rabbits[
233
Title
Perennial Garden Plants
Publication
 
Author
Thomas. G. S.
Publisher
J. M. Dent & Sons, London.
Year
1990
ISBN
0 460 86048 8
Description
A concise guide to a wide range of perennials. Lots of cultivation guides, very little on plant uses.
].

Edible Uses

Leaves - raw or cooked.
Seed - dried then ground into a powder and mixed with cornmeal or other cereals for making bread etc[
46
Title
Dictionary of Economic Plants.
Publication
 
Author
Uphof. J. C. Th.
Publisher
Weinheim
Year
1959
ISBN
-
Description
An excellent and very comprehensive guide but it only gives very short descriptions of the uses without any details of how to utilize the plants. Not for the casual reader.
,
61
Title
A Dictionary of Plants Used by Man.
Publication
 
Author
Usher. G.
Publisher
Constable
Year
1974
ISBN
0094579202
Description
Forget the sexist title, this is one of the best books on the subject. Lists a very extensive range of useful plants from around the world with very brief details of the uses. Not for the casual reader.
,
105
Title
Tanaka's Cyclopedia of Edible Plants of the World.
Publication
 
Author
Tanaka. T. & Nakao S.
Publisher
Keigaku Publishing; Tokyo
Year
1976
ISBN
-
Description
The most comprehensive list of edible plants I've come across. Only the briefest entry for each species, though, and some of the entries are more than a little dubious. Not for the casual reader.
,
161
Title
Food Plants of the N. American Indians. Publication no. 237.
Publication
 
Author
Yanovsky. E.
Publisher
U.S. Depf of Agriculture.
Year
 
ISBN
-
Description
A comprehensive but very terse guide. Not for the casual reader.
,
257
Title
Native American Ethnobotany
Publication
 
Author
Moerman. D.
Publisher
Timber Press. Oregon.
Year
1998
ISBN
0-88192-453-9
Description
Very comprehensive but terse guide to the native uses of plants. Excellent bibliography, fully referenced to each plant, giving a pathway to further information. Not for the casual reader.
]. The seed is rather small and fiddly to utilize, it is enclosed in a dry papery hull[
207
Title
The History and Folklore of North American Wild Flowers.
Publication
 
Author
Coffey. T.
Publisher
Facts on File.
Year
1993
ISBN
0-8160-2624-6
Description
A nice read, lots of information on plant uses.
].

Medicinal

None known

Other Uses

None known

Propagation

Seed - sow spring in a cold frame. Germination is usually free and easy. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer if they have reached sufficient size. If not, overwinter them in a cold frame and plant them out the following spring after the last expected frosts.
Division in spring or autumn. Very easy, larger divisions can be planted out direct into their permanent positions. We have found that it is better to pot up the smaller divisions and grow them on in light shade in a cold frame until they are well established before planting them out in late spring or early summer.
Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2018-06-22. <temperate.theferns.info/plant/Polygonum+douglasii>

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