Lenka Sprtova1 Why are leaves of Quaking Aspen (Populus tremuloides) s - PDF document

Lenka Sprtova1 Why are leaves of Quaking Aspen (Populus tremuloides) shivering? “Quaking aspen earns its name for the distinctive fluttering of its leaves, even in the most gentle breezes. Early French-Canadian trappers called the tree an aspen because of its similarity to Populus tremula, a closely related species in Europe and Asia. Quaking aspen merits a variety of superlatives: It is North America’s most widely distributed native tree species and the second most widely distributed in the world.” (Mitton, Grant, 1996)Leaves of Quaking aspen have unusual ability to tremble without even a breath of wind. There are many explanations. The botanists say that it is due to the flattened leaf stalk, which is set perpendicular to the surface of the leaf, making a combination which renders the foliage so susceptible to the slightest movement of air. It is also an adaptation to strong wind. The flat petiole permits the leaves to twist easily and reconfigure, accounting for the resistance of aspen and other poplars to wind damage. “It is also thought to improve the rate of photosynthesis throughout the tree by reducing the exposure of the outer leaves to extreme sunlight by presenting the leaves at an oblique angle to the sun throughout the day, while at the same time allowing more light through to the lower leaves which are generally over shaded. This would enable leaves throughout the tree to photosynthesize more efficiently. Another theory that has been advanced is that the constant motion aids the tree's growth: the constant movement is thought to increase the intake of air by the leaves, and hence the rate of carbon fixationfrom the air's carbon dioxide.” (Wikipedia, 2009) Another explanation is that leaves shiver in order to deter pests, who would like to lay eggs on the leaf. 2 Quaking aspen appears in different poems. Aspen has been made symbolical of fear or of lamentation. “Still another meaning assigned to it in floral language is scandal, from an old saying which affirmed that its leaves were made from tongues of malicious gossipers, a thought put into rhyme in 1622: The quaking aspen, light and thin, To the air quick passage gives; Resembling still The trembling ill Of tongues of womankind; Which never rest, But still are prest To wave with every wind. – P. Hannay William Browne, in Britannia’s Pastorals, ascribes it to the tree’s having witnessed the pursuit of a nymph by a wolf: An asp, who thought him stout, could not dissemble, But showed his fear, and yet is seen to tremble. Folklore ascribes this habit to the tree’s association with the life of Christ: Once as our Saviour walked with men below, His path of mercy through a forest lay, And mark how all the drooping branches show What homage best a silent tree may pay. Only the aspen stood erect and free, Scorning to join the voiceless worship pure, But see! He casts one look upon the tree, Struck to the heart, she trembles forevermore. – Anon” (Wilbur
1920) One legend informs us that as the Holy Family took their flight, they came into a thickly wooded forest, when, on their approach, all the trees, with exception of the Aspen, paid reverential homage. The disrespectful arrogance of the tree did not escape the notice of the Holy Child, but at His glance 3 its leaves began to tremble and have done so ever since. Another version places the event on the evening of the betrayal: By Kedron I stood, and the bright beaming eye I viewed of the pitying Power; Each tree bowed its head, as the Saviour passed by, But I deigned not my proud head to lower. Then sounded a sigh from the Saviour’s breast, And I quaked, for that sigh through my darted: “Quake so till I come!” said the voice of the Blest; My repose then forever departed. – Bernhard Severin Inglemann, “The Aspen” “The Russian peasants state that the tree trembles with horror and wrath because Judas hanged himself from its branches. They say: “The aspen is an accursed tree, which trembles without even a breath of wind.” The folklore of many different peoples agrees that the aspen is the tree from which the Cross was made, which explains its gloomy shivering recollections: Ah, tremble, tremble, Aspen tree, I need not ask thee why thou shakest, For if, as holy legend saith, On thee the Saviour bled to death, No wonder, Aspen, that thou quakest, And till the judgment all assemble, Thy leaves, accursed, shall wail and tremble. – Anon, “The Legend of the Aspen.” ” (Wilbur
1920)In Syria, this tree is called Khashafa, meaning “to be agitated,” and in Lithuania it is Drebulle, a word intimately connected with English word “tremble,” and which it means. The people of these two countries concur with the general belief that the Cross was made of aspen, and that the trembling of leaves is a proof that the tree was so employed: On the morrow stood she trembling, 4 At the awful weight she bore, When the sun in midnight blackness Darkened on Judea’s shore. – Anon, “The Legend of the Aspen.” Far off in highland wilds ‘tis said, (But truth now laughs at fancy’s lore), That of this tree the Cross was made, Which erst the Lord of glory bore, And of that deed its leaves confess, E’er since a troubled consciousness. – Anon, “The Aspen.” The mystery at the aspen can be accrued to simple biological advantage but needlessly for its mystery will never be resolved in the human imagination. Resources: Aspen [online]. 2009 , 23 September 2009 [cit. 2009-09-24]. Accessible from WWW: http://en.wikipedia.org/wiki/Aspen&#x-1.5;唴. How Wind Affects Trees. The woodland steward [online]. 2001, vol. 10, no. 1 [cit. 2009-09-24]. Accessible from WWW: http://www.fnr.purdue.edu/inwood/past%20issues/windaffe.htm .32;p. GRANT, Michael C., MITTON, Jeffry B. . Genetic Variation and the Natural History of Quaking Aspen. BioScience [online]. 1996, vol. 46, no. 1 [cit. 2009-09-22]. WILBUR, Harriette. The Quaking Aspen Tree. The Catholic world [online]. 1920, vol. 61 [cit. 2009-09-22]. Accessible from WWW: http://books.google.com/books&#x-1.5;嘀.