Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Betula papyrifera
open-in-new
<h2 id="description">Description</h2> <p><i>Betula papyrifera</i> is a medium-sized <a href="/facts/Deciduous/7jQHVtdd">deciduous</a> <a href="/facts/Tree/HVVn3srN">tree</a> typically reaching 20 metres (66 feet) tall,<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> and exceptionally to 40 m (130 ft) with a trunk up to 75 centimetres (30 inches) in diameter.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Within forests, it often grows with a single trunk but when grown as a landscape tree it may develop multiple trunks or branch close to the ground.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p><p>Paper birch is a typically short-lived species. It handles heat and humidity poorly and may live only 30 years in <a href="/facts/Hardiness_zone/zhPbV4Qb">zones six</a> and up, while trees in colder-climate regions can grow for more than 100 years.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> <i>B. papyrifera</i> will grow in many soil types, from steep rocky outcrops to flat <a href="/facts/Muskeg/gGjxEj3R">muskegs</a> of the boreal forest. Best growth occurs in deeper, well drained to dry soils, depending on the location.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> </p> <ul><li>In older trees, the <a href="/facts/Bark_(botany)/vdL49ec1">bark</a> is white, commonly brightly so, flaking in fine horizontal strips to reveal a pinkish or salmon-colored inner bark.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> It often has small black marks and scars. In individuals younger than five years, the bark appears a brown red color<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> with white <a href="/facts/Lenticel/1Fp6TIRG">lenticels</a>, making the tree much harder to distinguish from other birches. The bark is highly weather-resistant. It has a high oil content and this gives it its waterproof and weather-resistant characteristics.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> Often, the wood of a downed paper birch will rot away, leaving the hollow bark intact.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></li> <li>The <a href="/facts/Leaves/1m6wCNTg">leaves</a> are dark green and smooth on the upper surface; the lower surface is often <a href="/facts/Trichome/tLjKSfvm">pubescent</a> on the veins. They are alternately arranged on the stem, oval to triangular in shape, 4–10 cm (2–4 in) long and about two-thirds as wide. The leaf is rounded at the base and tapering to an acutely pointed tip. The leaves have a doubly serrated <a href="/facts/Leaf_margin/1m6wCNTg">margin</a> with relatively sharp teeth.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a><a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> Each leaf has a <a href="/facts/Petiole_(botany)/pext65Wr">petiole</a> about 2.5 cm (1 in) long that connects it to the stems.</li> <li>The fall color is a bright yellow color that contributes to the bright colors within the northern <a href="/facts/Deciduous_forest/7jQHVtdd">deciduous forest</a>.</li> <li>The leaf <a href="/facts/Bud/USYHoQv8">buds</a> are conical and small and green-colored with brown edges.</li> <li>The stems are a reddish-brown color and may be somewhat hairy when young.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a></li> <li>The <a href="/facts/Flower/7gI5Kefw">flowers</a> are wind-pollinated <a href="/facts/Catkin/PPE9klav">catkins</a>; the female flowers are greenish and 3.8 cm (1+1⁄2 in) long growing from the tips of twigs. The male (<a href="/facts/Staminate/MzNPVK3D">staminate</a>) flowers are 5–10 cm (2–4 in) long and a brownish color. The tree flowers from mid-April to June depending on location. Paper birch is <a href="/facts/Monoecious/Up20kQT3">monoecious</a>, meaning that one plant has both male and female flowers.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></li> <li>The <a href="/facts/Fruit/PBpuzk60">fruit</a> matures in the fall. The mature fruit is composed of numerous tiny winged <a href="/facts/Seed/a4xGSLxJ">seeds</a> packed between the catkin bracts. They drop between September and spring. At 15 years of age, the tree will start producing seeds but will be in peak seed production between 40 and 70 years.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> The seed production is irregular, with a heavy seed crop produced typically every other year and with at least some seeds being produced every year.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> In average seed years, 2,500,000 seeds per hectare (1,000,000 per acre) are produced, but in bumper years 86,000,000/ha (35,000,000/acre) may be produced. The seeds are light and blow in the wind to new areas; they also may blow along the surface of snow.</li> <li>The roots are generally shallow and occupy the upper 60 cm (24 in) of the soil and do not form taproots. High winds are more likely to break the trunk than to uproot the tree.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a></li></ul> <h2 id="genetics-and-taxonomy">Genetics and taxonomy</h2> <p><i>B. papyrifera</i> hybridizes with other species within the genus <i>Betula</i>. </p><p>Several varieties are recognized:<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> </p> <ul><li><i>B. p.</i> var <i>papyrifera</i> the typical paper birch</li> <li><i>B. p.</i> var <i>cordifolia</i> the eastern paper birch (now a separate species); see <a href="/facts/Betula_cordifolia/PA5fE8u4">Betula cordifolia</a></li> <li><i>B. p.</i> var <i>kenaica</i> Alaskan paper birch (also treated as a separate species by some authors); see <a href="/facts/Betula_kenaica/ALHTxGeW">Betula kenaica</a></li> <li><i>B. p.</i> var <i>subcordata</i> Northwestern paper birch</li> <li><i>B. p</i>. var. <i>neoalaskana</i> Alaska paper birch (although this is often treated as a separate species); see <a href="/facts/Betula_neoalaskana/9LEwuvIo">Betula neoalaskana</a></li></ul> <h2 id="distribution">Distribution</h2> <p><i>Betula papyrifera</i> is mostly confined to Canada and the far northern United States. It is found in interior (var. <i>humilus</i>) and south-central (var. <i>kenaica</i>) <a href="/facts/Alaska/LlDNr2uR">Alaska</a> and in all <a href="/facts/Provinces_and_territories_of_Canada/k3o89TLx">provinces and territories of Canada</a>, except <a href="/facts/Nunavut/aFaAad0W">Nunavut</a>, as well as the far northern continental <a href="/facts/United_States/P0sCdLe5">United States</a>. Isolated patches are found as far south as the Hudson Valley of <a href="/facts/New_York_(state)/mnl67G1G">New York</a> and <a href="/facts/Pennsylvania/HGqC5bBm">Pennsylvania</a>, northern <a href="/facts/Connecticut/LeDhYdJG">Connecticut</a>, and <a href="/facts/Washington_(state)/7tCrTFnN">Washington</a>. High elevation <a href="/facts/Forest_stand/WW0KQy8m">stands</a> are also in mountains to <a href="/facts/North_Carolina/VhKNTULI">North Carolina</a>, <a href="/facts/New_Mexico/wosJCGaW">New Mexico</a>, and <a href="/facts/Colorado/IgIHrJI5">Colorado</a>. The most southerly stand in the Western United States is located in Long Canyon in the <a href="/facts/Boulder%2c_Colorado/nlzuFHN2">City of Boulder Open Space and Mountain Parks</a>.<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> This is an isolated Pleistocene <a href="/facts/Relict_(biology)/eH1gkAg3">relict</a> that most likely reflects the southern reach of boreal vegetation into the area during the last Ice Age. </p> <h2 id="ecology">Ecology</h2> <p>In Alaska, paper birch often naturally grows in pure stands by itself or with <a href="/facts/Black_spruce/3QLJzeU5">black</a> or <a href="/facts/White_spruce/UGT4jv4c">white spruce</a>. In the eastern and central regions of its range, it is often associated with <a href="/facts/Red_spruce/Il201UUr">red spruce</a> and <a href="/facts/Balsam_fir/oa7QFoVY">balsam fir</a>.<a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a> It may also be associated with <a href="/facts/Big-Toothed_Aspen/aTmDS7AJ">big-toothed aspen</a>, <a href="/facts/Yellow_birch/HonSgav7">yellow birch</a>, <i><a href="/facts/Betula_populifolia/v3RRGWgm">Betula populifolia</a></i>, and <a href="/facts/Acer_(plant)/xCgQIY4z">maples</a>. </p><p>Shrubs often associated with paper birch in the eastern part of its range include beaked hazel (<i><a href="/facts/Corylus_cornuta/YwPMA2UJ">Corylus cornuta</a></i>), common bearberry (<i><a href="/facts/Arctostaphylos_uva-ursi/tL8rIPMu">Arctostaphylos uva-ursi</a></i>), dwarf bush-honeysuckle (<i><a href="/facts/Diervilla_lonicera/z6TzJtAW">Diervilla lonicera</a></i>), wintergreen (<i><a href="/facts/Gaultheria_procumbens/ot2U1XXS">Gaultheria procumbens</a></i>), wild sarsaparilla (<i><a href="/facts/Aralia_nudicaulis/mPILVsUj">Aralia nudicaulis</a></i>), blueberries (<i><a href="/facts/Vaccinium/SAMRbcfc">Vaccinium</a> spp.</i>), raspberries and blackberries (<i><a href="/facts/Rubus/GQhtfDfa">Rubus</a> spp.</i>), elderberry (<i><a href="/facts/Sambucus/ABVfL9zn">Sambucus</a> spp.</i>), and hobblebush (<i><a href="/facts/Viburnum_alnifolium/QmK9neNX">Viburnum alnifolium</a></i>).<a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a> </p> <h3>Successional relationships</h3> <p><i>Betula papyrifera</i> is a <a href="/facts/Pioneer_species/SAqbmqeE">pioneer species</a>, meaning it is often one of the first trees to grow in an area after other trees are removed by some sort of disturbance. Typical disturbances colonized by paper birch are <a href="/facts/Wildfire/LU3797A0">wildfire</a>, <a href="/facts/Avalanche/xm5qLRSC">avalanche</a>, or <a href="/facts/Windthrow/z0XYXtVd">windthrow</a> areas where the wind has blown down all trees. When it grows in these pioneer, or early <a href="/facts/Secondary_succession/yXPLtgkN">successional</a>, woodlands, it often forms stands of trees where it is the only species.<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> </p><p>Paper birch is considered well adapted to fires because it recovers quickly by means of reseeding the area or regrowth from the burned tree. The lightweight seeds are easily carried by the wind to burned areas, where they quickly germinate and grow into new trees. Paper birch is adapted to ecosystems where fires occur every 50 to 150 years<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> For example, it is frequently an early invader after fire in <a href="/facts/Black_spruce/3QLJzeU5">black spruce</a> <a href="/facts/Boreal_forest/xjkPQRJs">boreal forests</a>.<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a> As paper birch is a pioneer species, finding it within mature or climax forests is rare because it will be overcome by trees that are more <a href="/facts/Shade-tolerant/JKkK4J9e">shade-tolerant</a> as secondary succession progresses.<a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a> </p><p>For example, in Alaskan boreal forests, a paper birch stand 20 years after a fire may have 3,000–6,000 trees per acre (7,400–14,800/ha), but after 60 to 90 years, the number of trees will decrease to 500–800 trees per acre (1,200–2,000/ha) as spruce replaces the birch.<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a> After approximately 75 years, the birch will start dying and by 125 years, most paper birch will have disappeared unless another fire burns the area. </p><p>Paper birch trees themselves have varied reactions to wildfire. A group, or stand, of paper birch is not particularly flammable. The canopy often has a high moisture content and the understory is often lush green.<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a> As such, conifer crown fires often stop once they reach a stand of paper birch or become slower-moving ground fires. Since these stands are fire-resistant, they may become seed trees to reseed the area around them that was burned. However, in dry periods, paper birch is flammable and will burn rapidly.<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a> As the bark is flammable, it often will burn and may <a href="/facts/Girdling/9l6gdvjd">girdle</a> the tree. </p> <h3>Wildlife</h3> <p>Birch bark is a winter staple food for <a href="/facts/Moose/JDlB909Q">moose</a>. The nutritional quality is poor because of the large quantities of <a href="/facts/Lignin/CdaxpB3b">lignin</a>, which make digestion difficult, but is important to wintering moose because of its sheer abundance.<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a> Moose prefer paper birch over <a href="/facts/Aspen/jHmCqNtR">aspen</a>, <a href="/facts/Alder/KbD9YG8w">alder</a>, and <a href="/facts/Balsam_poplar/3cX803uP">balsam poplar</a>, but they prefer willow (<i><a href="/facts/Salix/F66Xvslm">Salix</a></i> spp.) over birch and the other species listed. Although moose consume large amounts of paper birch in the winter, if they were to eat only paper birch, they may starve.<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a> </p><p>Although <a href="/facts/White-tailed_deer/Y8FXTnhj">white-tailed deer</a> consider birch a "secondary-choice food," it is an important dietary component. In Minnesota, white-tailed deer eat considerable amounts of paper birch leaves in the fall. <a href="/facts/Snowshoe_hare/uWDsuFWM">Snowshoe hares</a> browse paper birch seedlings,<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a> and grouse eat the buds. <a href="/facts/North_American_porcupine/4vfC6DDV">Porcupines</a> and beavers feed on the inner bark.<a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a> The seeds of paper birch are an important part of the diet of many birds and small mammals, including <a href="/facts/Chickadee/qcxRbQTc">chickadees</a>, <a href="/facts/Redpoll/htKA50kG">redpolls</a>, <a href="/facts/Vole/yPC6PvYk">voles</a>, and <a href="/facts/Ruffed_grouse/YE8F6aKj">ruffed grouse</a>. <a href="/facts/Yellow_bellied_sapsucker/l1ytBmuQ">Yellow bellied sapsuckers</a> drill holes in the bark of paper birch to get at the sap; this is one of their favorite trees for feeding on.<a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a> </p> <h2 id="conservation">Conservation</h2> <p>As of 2023, the conservation status of paper birch is considered of least concern according to the International Union for Conservation of Nature (IUCN). However, the species is considered <a href="/facts/Vulnerable_species/79WNk4Gj">vulnerable</a> in <a href="/facts/Indiana/VRnvjXoQ">Indiana</a> and <a href="/facts/Nebraska/g9hHfRFU">Nebraska</a>, <a href="/facts/Conservation_status_(TNC)/3Kyo0LXv">imperiled</a> in <a href="/facts/Illinois/MuPb1Ctn">Illinois</a>, <a href="/facts/Virginia/g2kucGdn">Virginia</a>, and <a href="/facts/West_Virginia/USP8LtCq">West Virginia</a>, and <a href="/facts/Endangered_species/L7cIweSW">critically imperiled</a> in <a href="/facts/Colorado/IgIHrJI5">Colorado</a> and <a href="/facts/Tennessee/A3mLY9bu">Tennessee</a>.<a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a> These areas represent the southerly and southwesterly edge of the paper birch's range. </p> <h2 id="uses">Uses</h2> <p><i>Betula papyrifera</i> has a moderately heavy white wood. It makes excellent high-yielding firewood if seasoned properly. The dried wood has a density of 37.4 lb/cu ft (0.599 g/cm3) and an energy density 20,300,000 BTU/cord (5,900,000 kJ/m3).<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a> Although paper birch does not have a very high overall economic value, it is used in furniture, flooring, popsicle sticks,<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a> <a href="/facts/Pulpwood/bqDx6323">pulpwood</a> (for paper), <a href="/facts/Plywood/eM5WFvER">plywood</a>, and <a href="/facts/Oriented_strand_board/xnD9t0MF">oriented strand board</a>.<a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a> The wood can also be made into spears, bows, arrows, snowshoes, sleds, and other items.<a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a> When used as pulp for paper, the stems and other nontrunk wood are lower in quantity and quality of fibers, and consequently the fibers have less mechanical strength; nonetheless, this wood is still suitable for use in paper. </p><p>The sap is boiled down to produce <a href="/facts/Birch_syrup/urSX3xJz">birch syrup</a>. The raw sap contains 0.9% carbohydrates (<a href="/facts/Glucose/oUSkoLCD">glucose</a>, <a href="/facts/Fructose/pEqWJC2N">fructose</a>, <a href="/facts/Sucrose/7y1ke94L">sucrose</a>)<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a> as compared to 2 percent to 3 percent within <a href="/facts/Sugar_maple/nUscXhLM">sugar maple</a> sap. The sap flows later in the season than maples. Currently, only a few small-scale operations in Alaska and <a href="/facts/Yukon/JAGCCGCW">Yukon</a> produce birch syrup from this species.<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a> </p> <h3>Bark</h3> <p>Its bark is an excellent fire starter; it ignites at high temperatures even when wet. The bark has an energy density of 5,740 cal/g (24,000 J/g) and 3,209 cal/cm3 (220,000 J/cu in), the highest per unit weight of 24 species tested.<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a> </p><p>Birch bark is used in a number of crafts by various Native American tribes (e.g. Ojibwe).<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a> In the Ashinaabe language birch bark is called <i>wiigwaas</i>.<a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a> Panels of bark can be fitted or sewn together to make cartons and boxes. The bark is also used to create a durable waterproof layer in the construction of sod-roofed houses.<a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a> Many indigenous groups (i.e., Wabanaki peoples) use birchbark for making various items, such as canoes, containers,<a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a> and wigwams. It is also used as a backing for porcupine quillwork and moosehair embroidery. Thin sheets can be employed as a medium for the art of <a href="/facts/Birchbark_biting/jD8ky1Kv">birchbark biting</a>.<a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a> </p> <h3>Plantings</h3> <p>Paper birch is planted to reclaim old mines and other disturbed sites, often bare-root or small saplings are planted when this is the goal.<a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a> Since paper birch is an adaptable pioneer species, it is a prime candidate for reforesting drastically disturbed areas. </p><p>Paper birch is frequently planted as an <a href="/facts/Ornamental_plant/ImyCDwMW">ornamental</a> because of its graceful form and attractive bark. The bark changes to the white color at about 3 years of growth.<a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a> Paper birch grows best in USDA zones 2–6,<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a> due to its intolerance of high temperatures. <i><a href="/facts/Betula_nigra/6ksYzBj7">Betula nigra</a></i>, or river birch, is recommended for warm-climate areas warmer than zone 6, where paper birch is rarely successful.<a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a> <i>B. papyrifera</i> is more resistant to the bronze birch borer than <i><a href="/facts/Betula_pendula/xEth6vrV">Betula pendula</a></i>, which is similarly planted as a landscape tree. </p> <h2 id="pests">Pests</h2> <p><a href="/facts/Agrilus_anxius/nETKln8y">Bronze birch borer</a> is a major pest among birch species.<a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a> Under repeated infestation or stress to the tree from other sources, bronze birch borers may kill the tree.<a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a> The insect bores into the sapwood, beginning at the top of the tree and causing death of the tree crown.<a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a> The insect has a D-shaped emergence hole where it chews out of the tree. Healthy trees are resistant to the borer, but when grown in less than ideal conditions, the defense mechanisms of the tree may not function properly. Chemical controls exist.<a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a> </p><p><a href="/facts/Birch_skeletonizer/EToLR1Gs">Birch skeletonizers</a> are moths which lay their eggs on the surfaces of birch leaves.<a class="footnote-ref" id="fnref:60" href="#fn:60"><sup>60</sup></a> Upon hatching, the larvae feed on the undersides of the leaves and cause browning.<a class="footnote-ref" id="fnref:61" href="#fn:61"><sup>61</sup></a> </p><p><a href="/facts/Birch_leafminer/el4vXLBg">Birch leafminer</a> is a species of sawfly and a common pest that feeds from the inside of the leaf and causes the leaf to turn brown.<a class="footnote-ref" id="fnref:62" href="#fn:62"><sup>62</sup></a> It was introduced to the United States in the 1920s.<a class="footnote-ref" id="fnref:63" href="#fn:63"><sup>63</sup></a> The first generation appears in May but there will be several generations per year. Severe infestations may stress the tree and make it more vulnerable to the bronze birch borer.<a class="footnote-ref" id="fnref:64" href="#fn:64"><sup>64</sup></a> </p> <h2 id="external-links">External links</h2> Wikimedia Commons has media related to Betula papyrifera. <ul><li> Data related to Betula papyrifera at Wikispecies</li> <li><a href="http://www.efloras.org/object_page.aspx?object_id=5753&flora_id=1">Flora of North America – Distribution Map: <i>Betula papyrifera</i></a></li> <li><a href="https://pfaf.org/user/Plant.aspx?LatinName=Betula+papyrifera">"Betula papyrifera"</a>. <i><a href="/facts/Plants_for_a_Future/SfIWAPrk">Plants for a Future</a></i>.</li> <li><a href="http://calphotos.berkeley.edu/cgi/img_query?where-taxon=Betula+papyrifera"><i>Betula papyrifera</i></a> in the <a href="/facts/CalPhotos/eCY49YYF">CalPhotos</a> photo database, <a href="/facts/University_of_California%2c_Berkeley/MXVEjklr">University of California, Berkeley</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Betula papyrifera". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 11 December 2017. <a href="https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=7122" target="_blank">https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=7122</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Betula papyrifera". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 11 December 2017. <a href="https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=7122" target="_blank">https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=7122</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Betula papyrifera". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 11 December 2017. <a href="https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=7122" target="_blank">https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=7122</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Stafford, L.O. (1983). Silvicultural Guide for Paper Birch in the Northeast (Revised ed.). United States Department of Agriculture, Forest Service, Northeastern Forest Experiment Station, Research Paper NE-535. p. 8. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"Saskatchewan's Provincial Tree". Archived from the original on 2013-10-31. Retrieved 2013-03-06. <a href="https://web.archive.org/web/20131031141916/http://www.ops.gov.sk.ca/Default.aspx?DN=392f9e7f-7d31-4a9f-81d1-2b95e7fdc8c6" target="_blank">https://web.archive.org/web/20131031141916/http://www.ops.gov.sk.ca/Default.aspx?DN=392f9e7f-7d31-4a9f-81d1-2b95e7fdc8c6</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"Fast New Hampshire Facts". NH.gov. Retrieved August 28, 2012. <a href="http://www.nh.gov/nhinfo/fastfact.html" target="_blank">http://www.nh.gov/nhinfo/fastfact.html</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Furlow, John J. (1997). "Betula papyrifera". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 3. New York and Oxford: Oxford University Press – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA. <a href="http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260" target="_blank">http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Dirr, Michael A (1990). Manual of woody landscape plants (4. ed., rev. ed.). Champaign, Illinois: Stipes Publishing Company. ISBN 0-87563-344-7. <a href="0-87563-344-7" target="_blank">0-87563-344-7</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Dirr, Michael A (1990). Manual of woody landscape plants (4. ed., rev. ed.). Champaign, Illinois: Stipes Publishing Company. ISBN 0-87563-344-7. <a href="0-87563-344-7" target="_blank">0-87563-344-7</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Furlow, John J. (1997). "Betula papyrifera". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 3. New York and Oxford: Oxford University Press – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA. <a href="http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260" target="_blank">http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Furlow, John J. (1997). "Betula papyrifera". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 3. New York and Oxford: Oxford University Press – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA. <a href="http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260" target="_blank">http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Ewing, Susan (April 1, 1996). The Great Alaska Nature Factbook. Portland, Oregon: Alaska Northwest Books. ISBN 978-0-88240-454-7. <a href="978-0-88240-454-7" target="_blank">978-0-88240-454-7</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Furlow, John J. (1997). "Betula papyrifera". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 3. New York and Oxford: Oxford University Press – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA. <a href="http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260" target="_blank">http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500260</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Arno, Stephen F.; Hammerly, Ramona P. (2020) [1977]. Northwest Trees: Identifying & Understanding the Region's Native Trees (field guide ed.). Seattle: Mountaineers Books. pp. 215–219. ISBN 978-1-68051-329-5. OCLC 1141235469. <a href="978-1-68051-329-5" target="_blank">978-1-68051-329-5</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Dirr, Michael A (1990). Manual of woody landscape plants (4. ed., rev. ed.). Champaign, Illinois: Stipes Publishing Company. ISBN 0-87563-344-7. <a href="0-87563-344-7" target="_blank">0-87563-344-7</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Rhoads, Ann; Block, Timothy (5 September 2007). The Plants of Pennsylvania (2 ed.). Philadelphia Pa: University of Pennsylvania press. ISBN 978-0-8122-4003-0. <a href="978-0-8122-4003-0" target="_blank">978-0-8122-4003-0</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>Cooper, David J., ed. (Spring 1984). Ecological Survey of the City of Boulder, Colorado Mountain Parks (PDF) (Report). City of Boulder Parks and Recreation Department. p. 16. Retrieved 7 June 2023. <a href="https://webappsprod.bouldercolorado.gov/openspace/research-reports/docs/249_Cooper_David_Ecological-1-201307091303.pdf" target="_blank">https://webappsprod.bouldercolorado.gov/openspace/research-reports/docs/249_Cooper_David_Ecological-1-201307091303.pdf</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> <li id="fn:26"><p>Safford, L. O.; Bjorkbom, John C.; Zasada, John C. (2023-04-18). "Betula papyrifera Marsh". Forest Service, U.S. Department of Agriculture. Retrieved 2023-04-18. <a href="https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/betula/papyrifera.htm" target="_blank">https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/betula/papyrifera.htm</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></p></li> <li id="fn:27"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></p></li> <li id="fn:28"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></p></li> <li id="fn:29"><p>Hogan, C. Michael (2008). "Black Spruce (Picea mariana)". GlobalTwitcher. Archived from the original on 2011-10-05. Retrieved 2011-09-16. <a href="https://web.archive.org/web/20111005174426/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=44751" target="_blank">https://web.archive.org/web/20111005174426/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=44751</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></p></li> <li id="fn:30"><p>Arno, Stephen F.; Hammerly, Ramona P. (2020) [1977]. Northwest Trees: Identifying & Understanding the Region's Native Trees (field guide ed.). Seattle: Mountaineers Books. pp. 215–219. ISBN 978-1-68051-329-5. OCLC 1141235469. <a href="978-1-68051-329-5" target="_blank">978-1-68051-329-5</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></p></li> <li id="fn:31"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></p></li> <li id="fn:32"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></p></li> <li id="fn:33"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></p></li> <li id="fn:34"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:34" class="footnote-back-ref">↩</a></p></li> <li id="fn:35"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:35" class="footnote-back-ref">↩</a></p></li> <li id="fn:36"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:36" class="footnote-back-ref">↩</a></p></li> <li id="fn:37"><p>Peattie, Donald Culross (1953). A Natural History of Western Trees. New York: Bonanza Books. p. 385. <a href="/wiki/Donald_C._Peattie" target="_blank">/wiki/Donald_C._Peattie</a> <a href="#fnref:37" class="footnote-back-ref">↩</a></p></li> <li id="fn:38"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:38" class="footnote-back-ref">↩</a></p></li> <li id="fn:39"><p>"NatureServe Explorer 2.0". explorer.natureserve.org. Retrieved 2023-02-25. <a href="https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.128519/Betula_papyrifera" target="_blank">https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.128519/Betula_papyrifera</a> <a href="#fnref:39" class="footnote-back-ref">↩</a></p></li> <li id="fn:40"><p>"Wood – Combustion Heat Values". www.engineeringtoolbox.com. Retrieved 5 July 2016. <a href="http://www.engineeringtoolbox.com/wood-combustion-heat-d_372.html" target="_blank">http://www.engineeringtoolbox.com/wood-combustion-heat-d_372.html</a> <a href="#fnref:40" class="footnote-back-ref">↩</a></p></li> <li id="fn:41"><p>Bellis, Mary. "Popsicle – The History of the Popsicle". About.com. Archived from the original on January 2, 2013. Retrieved 2011-09-16. <a href="https://archive.today/20130102004213/http://inventors.about.com/library/inventors/blpopsicle.htm" target="_blank">https://archive.today/20130102004213/http://inventors.about.com/library/inventors/blpopsicle.htm</a> <a href="#fnref:41" class="footnote-back-ref">↩</a></p></li> <li id="fn:42"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:42" class="footnote-back-ref">↩</a></p></li> <li id="fn:43"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:43" class="footnote-back-ref">↩</a></p></li> <li id="fn:44"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:44" class="footnote-back-ref">↩</a></p></li> <li id="fn:45"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:45" class="footnote-back-ref">↩</a></p></li> <li id="fn:46"><p>Burns, Russell M; Honkala, Barbara H. (1990). Sylvics of North America: Hardwoods. Washington: U.S. Dept. of Agriculture, Forest Service u.a. ISBN 0-16-029260-3. Archived from the original on 7 February 2011. Retrieved 14 July 2016. <a href="0-16-029260-3" target="_blank">0-16-029260-3</a> <a href="#fnref:46" class="footnote-back-ref">↩</a></p></li> <li id="fn:47"><p>Emery, M.R.; Wrobel, A.; Hansen, M.H.; Dockry, M.; Moser, W.K.; Stark, K.J.; Gilbert, J.H. (2014). "Using Traditional Ecological Knowledge as a Basis for Targeted Forest Inventories: Paper Birch (Betula papyrifera) in the US Great Lakes Region". Journal of Forestry. 112 (2): 2. doi:10.5849/jof.13-023. <a href="https://doi.org/10.5849%2Fjof.13-023" target="_blank">https://doi.org/10.5849%2Fjof.13-023</a> <a href="#fnref:47" class="footnote-back-ref">↩</a></p></li> <li id="fn:48"><p>Emery, M.R.; Wrobel, A.; Hansen, M.H.; Dockry, M.; Moser, W.K.; Stark, K.J.; Gilbert, J.H. (2014). "Using Traditional Ecological Knowledge as a Basis for Targeted Forest Inventories: Paper Birch (Betula papyrifera) in the US Great Lakes Region". Journal of Forestry. 112 (2): 2. doi:10.5849/jof.13-023. <a href="https://doi.org/10.5849%2Fjof.13-023" target="_blank">https://doi.org/10.5849%2Fjof.13-023</a> <a href="#fnref:48" class="footnote-back-ref">↩</a></p></li> <li id="fn:49"><p>Ewing, Susan (April 1, 1996). The Great Alaska Nature Factbook. Portland, Oregon: Alaska Northwest Books. ISBN 978-0-88240-454-7. <a href="978-0-88240-454-7" target="_blank">978-0-88240-454-7</a> <a href="#fnref:49" class="footnote-back-ref">↩</a></p></li> <li id="fn:50"><p>Arno, Stephen F.; Hammerly, Ramona P. (2020) [1977]. Northwest Trees: Identifying & Understanding the Region's Native Trees (field guide ed.). Seattle: Mountaineers Books. pp. 215–219. ISBN 978-1-68051-329-5. OCLC 1141235469. <a href="978-1-68051-329-5" target="_blank">978-1-68051-329-5</a> <a href="#fnref:50" class="footnote-back-ref">↩</a></p></li> <li id="fn:51"><p>Wakim, Yvonne; Hirschfelder, Arlene; Dennis, Shannon Rothenberger Flynn (2016). Native American Almanac: More Than 50,000 Years of the Cultures and Histories of Indigenous Peoples. Visible Ink Press. p. 1273. <a href="#fnref:51" class="footnote-back-ref">↩</a></p></li> <li id="fn:52"><p>Uchytil, Ronald J. (1991). "Betula papyrifera". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 5 July 2016. <a href="https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html" target="_blank">https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html</a> <a href="#fnref:52" class="footnote-back-ref">↩</a></p></li> <li id="fn:53"><p>Dirr, Michael A (1990). Manual of woody landscape plants (4. ed., rev. ed.). Champaign, Illinois: Stipes Publishing Company. ISBN 0-87563-344-7. <a href="0-87563-344-7" target="_blank">0-87563-344-7</a> <a href="#fnref:53" class="footnote-back-ref">↩</a></p></li> <li id="fn:54"><p>Dirr, Michael A (1990). Manual of woody landscape plants (4. ed., rev. ed.). Champaign, Illinois: Stipes Publishing Company. ISBN 0-87563-344-7. <a href="0-87563-344-7" target="_blank">0-87563-344-7</a> <a href="#fnref:54" class="footnote-back-ref">↩</a></p></li> <li id="fn:55"><p>"Betula papyrifera - Paper Birch" (PDF). Retrieved 5 July 2016. <a href="http://hort.ifas.ufl.edu/trees/BETPAPA.pdf" target="_blank">http://hort.ifas.ufl.edu/trees/BETPAPA.pdf</a> <a href="#fnref:55" class="footnote-back-ref">↩</a></p></li> <li id="fn:56"><p>Rose, A.H.; Lindquist, O.H. (1997). Insects of Eastern Hardwood Trees. Ottawa: Natural Resources Canada, Canadian Forest Service, Forestry Technical Report 29. p. 95. <a href="#fnref:56" class="footnote-back-ref">↩</a></p></li> <li id="fn:57"><p>Rose, A.H.; Lindquist, O.H. (1997). Insects of Eastern Hardwood Trees. Ottawa: Natural Resources Canada, Canadian Forest Service, Forestry Technical Report 29. p. 95. <a href="#fnref:57" class="footnote-back-ref">↩</a></p></li> <li id="fn:58"><p>"Betula papyrifera - Paper Birch" (PDF). Retrieved 5 July 2016. <a href="http://hort.ifas.ufl.edu/trees/BETPAPA.pdf" target="_blank">http://hort.ifas.ufl.edu/trees/BETPAPA.pdf</a> <a href="#fnref:58" class="footnote-back-ref">↩</a></p></li> <li id="fn:59"><p>"Betula papyrifera - Paper Birch" (PDF). Retrieved 5 July 2016. <a href="http://hort.ifas.ufl.edu/trees/BETPAPA.pdf" target="_blank">http://hort.ifas.ufl.edu/trees/BETPAPA.pdf</a> <a href="#fnref:59" class="footnote-back-ref">↩</a></p></li> <li id="fn:60"><p>Rose, A.H.; Lindquist, O.H. (1997). Insects of Eastern Hardwood Trees. Ottawa: Natural Resources Canada, Canadian Forest Service, Forestry Technical Report 29. p. 65. <a href="#fnref:60" class="footnote-back-ref">↩</a></p></li> <li id="fn:61"><p>"Betula papyrifera - Paper Birch" (PDF). Retrieved 5 July 2016. <a href="http://hort.ifas.ufl.edu/trees/BETPAPA.pdf" target="_blank">http://hort.ifas.ufl.edu/trees/BETPAPA.pdf</a> <a href="#fnref:61" class="footnote-back-ref">↩</a></p></li> <li id="fn:62"><p>Rose, A.H.; Lindquist, O.H. (1997). Insects of Eastern Hardwood Trees. Natural Resources Canada, Canadian Forest Service, Forestry Technical Report 29. p. 85. <a href="#fnref:62" class="footnote-back-ref">↩</a></p></li> <li id="fn:63"><p>Rose, A.H.; Lindquist, O.H. (1997). Insects of Eastern Hardwood Trees. Natural Resources Canada, Canadian Forest Service, Forestry Technical Report 29. p. 85. <a href="#fnref:63" class="footnote-back-ref">↩</a></p></li> <li id="fn:64"><p>"Betula papyrifera - Paper Birch" (PDF). Retrieved 5 July 2016. <a href="http://hort.ifas.ufl.edu/trees/BETPAPA.pdf" target="_blank">http://hort.ifas.ufl.edu/trees/BETPAPA.pdf</a> <a href="#fnref:64" class="footnote-back-ref">↩</a></p></li> </ol>