Eastern Cottonwood 东部三角叶杨

Eastern Cottonwood Populus deltoides
Family: Salicaceae (Willow)
Branching: Alternate

东方三叶杨 Populus deltoides
科：杨柳科（柳树）
分枝：交替

Eastern Cottonwood is quite common in extreme southwestern Ontario.  It is often a huge tree, much larger than the other poplars.  In fact they are often the most massive trees around.  They also grow extremely fast and are very short lived.  Middle-aged trees of Balsam Poplar and Eastern Cottonwood are often difficult to distinguish (they also hybridize naturally).  Very brown-red buds (Balsam) as opposed to very yellow (Cottonwood) may help, as will the presence of noticeable ridges running down the tips of the twigs (Cottonwood).  If there are any leaves clinging to the tree, the leaf stalk will help; round leaf stalks are Balsam Poplar and flattened leaf stalks are Cottonwood.  On mature trees, the enormous trunk is often enough to identify it, along with the deeply furrowed bark.  The twigs and buds tend to be much larger than other poplars (though Balsam Poplar can be large as well).  They probably share the "largest bud" distinction with Horsechestnut.  

东部三角叶杨树在安大略省的西南部很常见。它通常是一棵巨大的树，比其他杨树大得多。事实上，它们通常是它周围最大的树木。它们的生长速度也非常快，而且寿命很短。中年的香脂杨和东部三角叶杨通常很难区分（它们之间也自然地杂交）。香脂杨有非常棕红色的芽，而东部三角叶杨有非常黄色的芽。另外，三角叶杨的小枝从尖端开始有明显的脊。如果树上有叶子，香脂杨是圆叶柄，三角叶杨是扁平叶柄。这些都有助于我们区分它们。在成熟的树上，巨大的树干以及深深的皱纹树皮通常足以识别它。三角叶杨的枝条和芽往往比其他杨树大得多（尽管香脂杨树也可能很大）。他们可能与马栗子树都享有共享“最大芽”的特色。

全文看这里。

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今天去 Rouge National Urban Park, Bob Hunter Memorial Park 剪了一些东部三角叶杨的插枝。有一棵的枝条都很长，脊特别明显，这样的枝条都特别软，很容易就剪下来了，枝条也特别轻。它们与上文中图片完全一样。

我回家后又去 Parkview Public School，仔细看了那里的有一定年头的三角叶杨树， 只有从枝条的尖端下来有一些不明显的脊。那里的一棵幼树也是如此。

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香脂杨在加拿大的分布范围比东部三角叶杨要大得多。他们之间还杂交，因此两棵杨树可能有些不同的特征。