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| Practical ecological knowledge for the temperate reader. |
Populus Sp. - Cottonwood
Family: Salicaceae - Willow Family [E-flora]
"40 species: northern hemisphere. (Latin: name for plants of this genus) [Hamzeh et al. 2006 J Torrey Bot Soc 133:519–527]"[Jepson2012]
Local Species;
- Populus balsamifera ssp trichocarpa - Black Cottonwood [PCBC][TSFTK]
- Populus tremuloides - trembling aspen [TSFTK][PCBC][E-flora]
Populus Sp.;
Hazards
- Contraindicated in cases of hypersensitivity to salicylates." [PDR]
- "Contraindicated in cases of hypersensitivity to salicylates, propolis and balsam of Peru, which may be a componant in commercially available ointments.." [PDR]
- "External administration of the drug occasionally leads to allergic skin reactions." [PDR]
"Production: Poplar bark consists of the fresh or dried bark of salicin-rich Poplar species as well as their preparations. Poplar leaves consist of the leaves of salicin-rich Poplar species as well as their preparations. Poplar buds consist of the dried, unopened leaf buds of Populus species, as well as their preparations." [PDR]
Medicinal Uses
- Bark and Leaves:
- Unproven Uses: Poplar bark and leaves are used for pain and rheumatism therapy; and in micturition complaints due to prostate hypertrophy.." [PDR]
- Leaf buds
- Poplar buds have antiphlogistic, antibacterial and wound healing effects.." [PDR]
- Approved by Commission E: Hemorrhoids, Wounds and bums." [PDR]
- Unproven Uses: Poplar buds are used for superficial skin injuries, external hemorrhoids, frostbite and sunburn." [PDR]
Phytochemicals
- Bark & Leaves
- "Glycosides and esters yielding salicylic acid: In Populus alba (leaf 6%, bark 2%) chief components: salicortin, tremulacin, salicin." [PDR]
- "In Populus nigra (leaf 2%, bark 1.5%) chief components: salicortin, salicin." [PDR]
- "In Populus tremula (leaf 3% , bark 2%) chief components: salicin, tremulacin, salicortin including as well as salireposide, populin, tremuloidin." [PDR]
- Effects
- "Poplar bark and leaves have antiphlogistic, analgesic, antibacterial and spasmolytic effects. The salicylate acid derivatives and flavonoids are responsible for the antiphlogistic, analgesic, spasmolytic and antibacterial characteristics of the drug. The beneficial effect in micturition complaints due to prostate hypertrophy may be due to the content of zinc lignans in the drug." [PDR]
- Leaf Buds
- "Flavonoids: (particularly in the glutinous coating of the buds, also yielding propolis) including chrysin, tectochrysin, galengine, izalpinine, galangin-3-methyl ether, kaempferol- 3-methyl ether, pinocembrin, pinocembrin-7-methyl ether, apigenin Glycosides and esters yielding salicylic acid: including salicin, populin." [PDR]
- "Volatile oil: chief components alpha- and beta-caryophyllene." [PDR]
Dosages
- Daily Dosage (Bark and Leaves): "10 gm of drug." [PDR]
- Leaf buds
- How Supplied: "Semi-solid preparations equivalent to 20% to 30% of drug.." [PDR]
- Daily Dosage: "Externally, 5 gm drug.." [PDR]
Populus balsamifera ssp. trichocarpa
"Populus trichocarpa is a deciduous Tree growing to 40 m (131ft) by 12 m (39ft) at a fast rate.
It is hardy to zone (UK) 5. It is in flower from Apr to May, and the seeds ripen from May to June. The flowers are dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required) and are pollinated by Wind.The plant is not self-fertile. [PFAF]
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in heavy clay soil. Suitable pH: acid, neutral and basic (alkaline) soils and can grow in very acid soils.
It cannot grow in the shade. It prefers moist soil." [PFAF]
SUBTAXA PRESENT IN BC
- Populus balsamifera ssp. balsamifera
- Populus balsamifera ssp. trichocarpa
General: Dioecious tree up to 50 m tall; not colonial; branches brown the first year, turning grey later; twigs smooth or sparsely hairy. [IFBC-E-flora]
Leaves: Alternate, deciduous, simple, narrowly to broadly egg-shaped or lanceolate, 5-20 cm long, 3-12 cm wide, the bases tapered to heart-shaped or squared-off smooth, finely toothed and hairy on the margins, the teeth often tipped with a callous gland, lower side whitish or pale green and brownish; leaf stalks 2-10 cm long, often with a pair of glands near the blade; buds finely hairy with fringed scales. [IFBC-E-flora]
Flowers: Borne in catkins; male catkins 2-3 (5) cm long, soon deciduous, with 8-60 stamens; female catkins 8-20 cm long. [IFBC-E-flora]
Fruits: Capsules, broadly egg-shaped, carpels 2-3, smooth or hairy, nearly unstalked. [IFBC-E-flora]
Notes:
Two subspecies occur in BC. The hybrids P. angustifolia James x P. balsamifera ssp. trichocarpa (P. x brayshawii Boivin) and P. balsamifera ssp. trichocarpa x P. nigra L. var. italica DuRoi are rare in BC .
1. Ovaries and capsules smooth; leaves pale green and brownish beneath.................... ssp. balsamifera
1. Ovaries and young capsules hairy; leaves whitish beneath.................... ssp. trichocarp (T. & G.) Brayshaw [IFBC-E-flora]
USDA Flower Colour: Yellow
USDA Blooming Period: Mid-Spring
USDA Fruit/Seed characteristics:
Colour: White
Present over the Spring [USDA-E-flora]
Habitat / Range
Moist uplands and floodplains in the montane zone; ssp. balsamifera - common in N and E BC; ssp. trichocarpa - common throughout BC except rare on Queen Charlotte Islands; ssp. balsamifera - N to YT, AK and NT, E to NF and S to NY, VA, IL, IA, CO, ID and OR; ssp. trichocarpa - N to S AK and YT, E to SW AB and S to ND, WY, UT, NV and CA. [IFBC-E-flora]
Origin Status: Native [E-flora]
Edible Uses
- Cambium: The Northern Kwakiutl used to eat the
cambium in the early spring (Olson,
1954). Perhaps the Southern Kwakiutl
did also. " [Turner&Bell]
Other Uses
- Hairwash: "The sticky, sweet-smelling buds
were mixed with ratfish oil and used for
hair tonic (King, 1972)." [Turner&Bell] "The Songish pulverized the
fruit and mixed it with fish oil for a hair
tonic to make the hair grow long (Boas,
1890)." [Turner&Bell] "The buds with their resin boiled and the decoction used as a hair
wash. See also white fir." [Smith(1927)] Gummy buds boiled and the resin mixed with bear grease for a
hair perfume.Roots, leaves, and seeds not used.[Smith(1927)]
- Sunscreen: "The sticky, sweet-smelling buds
were... also
rubbed on women's faces to prevent sunburn (op. cit. )." [Turner&Bell]
- Cosmetic/Repellent: "Resin from the buds applied to the face as a cosmetic, or, with the
addition of oil, to repel mosquitoes, black flies, and gadflies." [Smith(1927)]
- Wood: "The wood was used for canoes by the
Island Salish. It was easy to carve, but too
spongy, and often the canoes became waterlogged. The Puget Sound Salish used the
wood as a hearth in making friction fires
(Haeberlin and Gunther, 1930)." [Turner&Bell]
- Waterproofing: "The sticky
gum was apparently used by the Island Salish
for waterproofing baskets and boxes (Ravenhill, 1938)." [Turner&Bell]
Medicinal:
- Bath Additive (for pains): "Leaves, ten to fifteen years old, from the lower layers lying
rotting on the ground, boiled, and the decoction used as a bath, the
patient sitting in it up to his neck for about two hours to cure pain in
the body, not rheumatism. A hot stone added from time to time, and the
bath repeated the next day." [Smith(1927)]
- Rheumatism: Half a cupful of buds, picked some time between December and
March, mixed with two roots of cow parsnip (Heracleum lanatum Michx.), a half cupful of buds of mountain alder (Alnus tenuifolia Nutt.), and a little water, mashed, and applied warm, but uncooked, as
a poultice for pains in the lungs or hips like rheumatism. Said to effect a
cure in two days, but harmful if left on longer. See also western dock." [Smith(1927)]
- Expectorant: "Buds with their resin boiled for one or two hours, and
the decoction taken internally for coughs and lung affections." [Smith(1927)]
- Styptic: "Green roots chewed to a pulp and applied to wounds
to stop bleeding." [Smith(1927)]
- Eye Wash: "Inside bark boiled and the decoction used as an eye-wash." [Smith(1927)]
Cultivation
"A very easily grown plant, it does well in a heavy cold damp soil[1]. Prefers a deep rich well-drained circumneutral soil, growing best in the south and east of Britain[11, 200]. Growth is much less on wet soils, on poor acid soils and on thin dry soils[11] but this species is more tolerant of acid soils than other members of the genus[11]. It dislikes shade and is intolerant of root or branch competition[11, 200]. Plants are reasonably wind resistant, but they do not grow well in exposed upland sites[11]. Many forms of this species are susceptible to bacterial canker, the female clone 'Fritzi Pauley' is resistant[11, 200]. A very fast growing[11] and ornamental tree[1], it does well in western Britain where trees have reached 25 metres tall in 20 years[11]. The leaf buds, as they swell in the spring, and the young leaves have a pleasing fragrance of balsam[245]. The fragrance is especially pronounced as the leaves unfold[245]. Poplars have very extensive and aggressive root systems that can invade and damage drainage systems. Especially when grown on clay soils, they should not be planted within 12 metres of buildings since the root system can damage the building's foundations by drying out the soil[11]. Dioecious. Male and female plants must be grown if seed is required." [PFAF]
Wildlife: Populus catkins, buds, leaves, and shoots are browse for moose and rabbits. American Medicinal Plants notes that quaking aspen shoots and leaves are gathered in Sweden and fed to domestic sheep in winter. Trappers often use quaking aspen as bait in beaver sets. Bees chew the resins of poplar and other trees, mix them with their enzymes, and regurgitate as bee glue. [Schofield]
Propagation
"Seed - must be sown as soon as it is ripe in spring[113]. Poplar seed has an extremely short period of viability and needs to be sown within a few days of ripening[200]. Surface sow or just lightly cover the seed in trays in a cold frame. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in the old frame. If sufficient growth is made, it might be possible to plant them out in late summer into their permanent positions, otherwise keep them in the cold frame until the following late spring and then plant them out. Most poplar species hybridize freely with each other, so the seed may not come true unless it is collected from the wild in areas with no other poplar species growing[11]. Cuttings of mature wood of the current season's growth, 20 - 40cm long, November/December in a sheltered outdoor bed or direct into their permanent positions. Very easy. Suckers in early spring[78]." [PFAF]
Synonyms
- Populus balsamifera var. californica S. Wats. [E-flora]
- P. balsamifera trichocarpa. (Torr.&Gray.)Brayshaw. [PFAF]
- Populus hastata Dode p.p. [E-flora]
- Populus trichocarpa Torr. & A. Gray ex Hook. [E-flora][PFAF]
- Populus trichocarpa subsp. hastata (Dode) Dode p.p. [E-flora]
- Populus trichocarpa var. cupulata S. Watson [E-flora]
- Populus trichocarpa var. hastata (Dode) A. Henry p.p. [E-flora]
- Populus trichocarpa var. ingrata (Jeps.) Jeps. [E-flora]
Trembling Aspen - Populus tremuloides
"Populus tremuloides is a deciduous Tree growing to 20 m (65ft) by 10 m (32ft) at a fast rate." [PFAF]
Origin Status: Native [E-flora]
Hazards
- "Contraindications and warnings associated with salicylates." [HerbalMed3]
- "... the potential for preparations of poplar to interact with other medicines administered concurrently, particularly those with similar or opposing effects, should be considered. The concurrent administration of poplar with other salicylate-containing medicines should be avoided. Drug interactions listed for salicylates are also applicable to poplar and include oral anticoagulants, methotrexate, metoclopramide, phenytoin, probenecid, spironolactone and valproate (see Willow for more information on drug interactions with salicylates)."[HerbalMed3]
- Pregnancy and lactation "The safety of poplar taken during pregnancy has not been established (see Willow for contraindications and warnings regarding the use of salicylates during pregnancy and lactation). Use of poplar during pregnancy and lactation should be avoided."[HerbalMed3]
Food Use:
- "The cambium was eaten raw by some Indian groups in the spring".[Turner&Bell]
- "Like spruce, pine and hemlock, aspen has a substantial and good-tasting cambium layer that can be scraped off the surface of the wood in late spring and early summer. This edible cambium can be dried for future use." [Northern Bushcraft]
Other Uses
- Chalky white powder: "Quaking aspen is commonly known as white poplar, so named for the chalky white powder that forms on the trunk of the tree at certain times of the year. Most of the powder is produced on the side lacing the direct rays of the sun. The white patches that may be found on any side of the tree are a white lichen." [Northern Bushcraft]
- Sunscreen: "The chalky material is a reflective sun screen that prevents the premature rising of sap from the warmth of the late winter sun. Should the sap rise and freeze, the tree will be damaged. The powder can be dusted on exposed skin to help prevent sunburn." [Northern Bushcraft]
- Paint: "Some Native people mixed the powder with the vitreous humor of the eye balls of large animals to make a paint for the body or for their artifacts." [Northern Bushcraft]
- Talcum Powder: "The powder can be used as a passable talcum. Stockings may be turned inside out and gently rubbed in the powder to reduce chafing." [Northern Bushcraft]
- Weak Binding: "Aspen roots are relatively weak, difficult to gather, and only suitable for weak bindings." [Northern Bushcraft]
- Wood
- "Properly cured aspen wood is quite hard, almost white in color with a fine uniform texture. It is almost odorless and tasteless. The wood is suitable for furniture, kitchen utensils and carving. Aspen is durable like birch only if kept dry and not allowed ground contact. In pioneer days, it proved a passable substitute for hickory or ash for the wooden components of horse drawn equipment. Aspen doubletrees were buried in sodden horse manure which improved the strength and durability of the wood, making it comparable to that of the eastern hardwoods." [Northern Bushcraft]
Straight, sound, knot-free trees are selected for woodcarving. The bark is peeled off in May or June and the tree allowed to stand or is cut up and stored in a dry place for a few years to cure. Frozen aspen splits remarkably easily. A wooden teepee or lean-to can be quickly made with the halves." [Northern Bushcraft]
- "Frozen aspen splits remarkably easily. A wooden teepee or lean-to can be quickly made with the halves." [Northern Bushcraft]
- "In the Northern Forests, aspen is second to willow as a favourite open-firewood because of its good blazing proper- Lies and pleasant smoke. The coals are short-lived and the ash is whitish-grey, smooth and fluffy. Sometimes the ash is employed as a crude baking powder. Canadian aspen was renowned the world over as a matchwood with an ember that extinguishes quickly, thereby reducing the chances of it blazing up after the flame is extinguished. When water is scarce for putting out a campfire. aspen may be the appropriate fuel to use. When required, aspen may be burned green providing it is split and the starting fire is hot." [Northern Bushcraft]
- "Occasionally wood is used as fuel, and
branches are made into switches to brush away mosquitoes. (No. 803). [Holloway]
- Bark
- Forage: "Aspen bark is an important food for beaver, moose, elk and varying hare. Horses can subsist on it when all other feed is scarce. In winter, it has to be chopped off for the horses, but in the spring, when the bark comes off easily, felling the tree is sufficient as the horses can peel the bark off for themselves." [Northern Bushcraft]
- "Like all other Northern Forest trees, aspen will peel easily from late May to mid-August. The bark can be used to make first aid splints of all sizes or folded into temporary containers and cooking vessels for use with hot rocks. As a shingle it must be tied or weighed down to prevent curling. It can be used under sod or moss, but is not as durable as conifer bark and is somewhat inferior to birch bark. The bark makes a handy flume when collecting water from small hillside springs." [Northern Bushcraft]
- Smoke: "The Upper Tanana of Alaska used smoke from burning wood to preserve their fish (Kari 1985). The Woodland Cree of North America, in contrast, smoked the plant during ceremonies (Whiting 1939). They used the inner bark in their kinnikinnick mixtures (Blankinship 1905). The species mentioned in the original text was Populus aurea Tidestr." [UAPDS]
Medicinal Use:
- Bark:
- "Poplar is stated to possess antirheumatic, anti-inflammatory, antiseptic, astringent, anodyne and cholagogue properties. Traditionally, it has been used for muscular and arthrodial rheumatism, cystitis, diarrhoea, anorexia with stomach or liver disorders, common cold, and specifically for rheumatoid arthritis.(G6,G7,G64) The buds of Populus tremula (European white poplar, aspen) and Populus nigra (black poplar) are used, reputedly as expectorant and circulatory stimulant remedies, for upper respiratory tract infections and rheumatic conditions.(G49)" [HerbalMed3]
- Dosage
- "Dosages for oral administration (adults) for traditional uses recommended in standard herbal reference texts are given below. Dried bark 1–4g as a decoction three times daily.(G6,G7) Liquid extract 1–4mL (1:1 in 25% alcohol) three times daily.(G6,G7)"
[HerbalMed3]
"Powdered bark. Dose, one dram two or three times a day. Saturated tincture of the bark, from one-half to twenty drops. Populin, one-tenth of a grain." [Ellingwood]
"Therapy—The older writers were enthusiastic concerning the tonic and antiperiodic properties of this drug. They claimed that it would replace quinine in the treatment of intermittency. It has never come into general use. A recent writer says that he soon learned that a strong infusion of the bark would cure those forms of intermittent fever, of a chronic or irregular character. At the same time the pathological lesions of the liver, spleen and kidneys which accompanied the chronic disorder, would gradually disappear with the ultimate complete restoration of their physiological functions. These results were accomplished without the unpleasant effects that occur after the protracted use of quinine. This writer, passing through an epidemic of severe malarial disease, found that malarial hematuria was very common and very hard to cure. He put his patients upon the infusion of cottonwood bark, and found the symptoms to yield rapidly, not only the hemorrhage, but the icterus, and other conditions depending upon disarrangement of the liver and stomach. He found that results obtained by this remedy were more permanent than those obtained by the use of quinine in some cases.
Protracted fevers, with debility and emaciation, are greatly benefited by the use of this remedy, and the conditions remaining in early convalescence are quickly overcome. The agent is a tonic to the kidneys, increasing their functional activity, relieving vesical and urethral tenesmus. it will also overcome prostatic hypertrophy in some cases, and is available in uterine congestion. It is of service in impaired digestion, either gastric or intestinal, chronic diarrhoea, with general debility. Other specific remedies may here be given in conjunction with it. Dr. Alter says that it corrects errors of physiological metabolism, induced by malarial toxemia. It is a most powerful antiperiodic. It will not cause deafness. It will not cause abortion, but on the contrary will prevent abortion, which is threatened by the presence of malarial conditions. It shows its influence best where there is general debility, very marked, with impairment of the nutritive functions of the body." [Ellingwood]
"Dr. Fearn says, concerning populus, this remedy is a powerful stimulant, tonic, and diuretic. And this statement fixes its place in treatment, in the hands of the true specific medicationist. When we use this remedy as a tonic or diuretic, we should never use it in cases accompanied with irritation whether it be of the stomach, bowels, uterus, bladder, or prostate. In atonic conditions of all these different organs where we desire to stimulate and tone up the organ, populus is a grand remedy. When first I began to use this Sampson among remedies of its class, I had to use decoctions of the bark—it was a nasty, bitter dose. How much better to use the specific medicine in from five to twenty drop doses. Dr. Howe reported a case where a soldier had chronic diarrhea which may have been caused by malaria. Howe put him on populus for a time and made a complete cure. If a little of the poplar bark be put into a cup and covered with boiling water, this will make a strong enough infusion for many conditions, taking only a teaspoonful or two at a time." [Ellingwood]
"Dr. Alter of Arkansas has given it for many years for swamp fever. He also uses it in the irregularities of women. He thinks it acts somewhat as hydrastis in promoting a physiological action of all organs, and increasing the vital force within the system. It may be well given in conjunction with hydrastis. Dr. Alter used it very widely whether it was strictly indicated or not, and became convinced of its active therapeutic property." [Ellingwood]
"The Forest Potawatomi sometimes use the Ojibwe name for this “asa'dis” [rabbit food]. The Prairie Potawatomi call it “mîtwi”. The Forest Potawatomi burn the bark of the Quaking Aspen and save the ashes to mix with lard which forms a salve to apply to sores upon horses. Among the whites282 the bark is valued for its tonic, stomachic, febrifuge and aperient properties. Another authority283 records the use of the bark and leaves in acute rheumatism, to lower the temperature in fevers, to relieve pain and to reduce arterial swellings, to treat coryza, hay-fever, influenza, neuralgia and diabetes. Among eclectic practitioners, it has been used externally as a wash for gangrenous wounds, eczema, cancer, burns, fetid perspiration and as a wash. When it is used as a wash, borax is added to the bark extract." [HuronSmith Zuni]
- "Bella Coola: A quantity of bark from the roots boiled, and the decoction taken internally from seven to ten times a day for gonorrhoea with hemorrhage from the urethra. A very bitter decoction, said to be a good remedy that stopped the hemorrhage" [Smith(1927)]
- "Southern Carrier: Bark used instead of tideland spruce bark to make a decoction for pain in the stomach. Considered inferior to the spruce bark" [Smith(1927)]
- "Sikani : Bark pulverized by pounding, moistened with water, and applied as a paste to wounds" [Smith(1927)]
- "Bark scraped, scrapings steeped in hot water, and the decoction taken internally for worms. Caused a stool immediately" [Smith(1927)]
- "Gitksan : Bark of roots chewed or mashed and put on cuts. Bark alone boiled, and the decoction taken internally as a purgative. Not an emetic." [Smith(1927)]
Lore
- Gender: Masculine [EMH Cunninghamn]
- Planet: Mercury [EMH Cunninghamn]
- Element: Air [EMH Cunninghamn]
- Powers: Eloquence, Anti-Theft [EMH Cunninghamn]
Phytochemicals
- Glycosides Salicin (about 2.4%), salicortin, salireposide and various benzoate derivatives including populin (salicin-6-benzoate), tremuloidin (salicin-2-benzoate) and tremulacin (salicortin-2- benzoate).[HerbalMed3]
- Other constituents Tannins (unspecified), triterpenes including a-amyrin and b-amyrin, carbohydrates including glucose, fructose and various trisaccharides, fats, waxes.[HerbalMed3]
Cultivation and Propagation
"A fast-growing tree, it rapidly invades bare areas such as logged woodland and soon establishes dense stands of young trees by sending up suckers[226, 229]. It provides excellent conditions for other species of trees to become established and these will eventually out-compete the poplar[229].
… Unlike most members of the genus, this species is drought tolerant once it is established[226]. It is fairly wind tolerant, though it does not do well in exposed upland sites[11]. It dislikes shade and is intolerant of root or branch competition[200]. A fast-growing species that is quite short-lived, though occasional specimens live to almost 200 years[229]. Poplars have very extensive and aggressive root systems that can invade and damage drainage systems. Especially when grown on clay soils, they should not be planted within 12 metres of buildings since the root system can damage the building's foundations by drying out the soil[11]. Dioecious. Male and female plants must be grown if seed is required."[PFAF]
"Seed - must be sown as soon as it is ripe in spring[113]. Poplar seed has an extremely short period of viability and needs to be sown within a few days of ripening[200]. ... This species is rather difficult from cuttings[11, 113]. Suckers in early spring[78]. Root cuttings in the winter[200]. Layering[200]."[PFAF]
Mycological Associations
"Parasitic mushrooms found on the living tree are Armellaria mellia, Pholiota squarrosoides and P. squarrosa. The delectable oyster mushroom, Pleurotus is often found on dead aspen. A symbiotic associate of aspen is the interesting and poisonous hallucinogenic Amanita musscaria. The sweetened broth of this fungus is a potent fly-killer. The root-like structure of A. muscaria and the terminal rootlets of aspen together form a joint structure called a mvchorrhiza. The fungus derives some of its nutrition from the structure, but what the tree derives from it is not clearly understood. Young aspen will die in the absence of this fungus." [Northern Bushcraft]
References
- [1]http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Populus tremuloides&redblue=Both&lifeform=2, [Accessed: 1/11/2015] [E-flora]http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Populus balsamifera&redblue=Both&lifeform=2, Accessed Jan 12, 2015
- [Holloway] Ethnobotany of the Fort Yukon Region, Alaska, PATRICIA S. HOLLOWAY2 AND GINNV ALEXANDER, Economic Botany, 44(2), 1990
- [Jepson2012] John O. Sawyer, Jr., 2012. Populus, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=39452, accessed on Mar 6 2014
- [Northern Bushcraft] Northern Bushcraft, Mors L. kochanski.
- [PFAF] http://www.pfaf.org/user/Plant.aspx?LatinName=Populus+tremuloides Plants for a future, Accessed Jan 12, 2015
- [PFAF]http://www.pfaf.org/user/Plant.aspx?LatinName=Populus+trichocarpa, Accessed Jan 12, 2015
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