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The Loom

October 18, 2004

In The Papers

I have an article in tomorrow's New York Times about the mystery of autumn leaves. Insect warning? Sunscreen? The debate rages. The one thing I was sad to see get cut for space was the statement by one of the scientists that the answer might be "all of the above." This sort of multitasking is the cool--and sometimes maddening--thing about living things. Very important, and very hard to sort out.

Posted by Carl at 8:27 PM
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I had always noticed that if a healthy tree limb is cut off with healthy leaves, the leaves will not go through the usual autumn color transitions. Instead the leaves brown and wither away, calling into question, as your elucidating article does, the commonly held notion of the fall "dying leaves." I have also noticed that the dead leaves from a severed tree limb will often remain firmly attached to the tree limb for a considerable amount of time longer than their autumn counterparts. Perhaps the trees have also evolved an adaptation for dislodging the leaves from the limbs in the autumn to allow new growth in the spring?

Posted by Jed Askari on October 19, 2004 02:16 PM | Permalink to Comment

The trees use abscisic acid to dislodge the leaves.

Best,

D

Posted by Dano on October 21, 2004 03:17 PM | Permalink to Comment
Le bronzage automnal des érables

Excerpt: Les cours d'écologie du secondaire nous ont appris que la coloration automnale des arbres vient du fait que la diminution de la période d'ensoleillement cause la dégradation de la chlorophylle (un pigment vert) à l'intérieur des feuilles et que les...

Read the rest...

Trackback from Tension superficielle, Oct 23, 2004 8:42 PM

Jed: Leaf abscission is an active cellular process--on a severed branch the process does not happen and the leaves won't fall off in the normal, living way. If you mutate certain proteins involved in abscission, the leaves won't fall off at all; if you sever the branch it follows that the abscission process is aborted. The breakdown of chlorophyll is also an active process involving many cellular proteins and trafficking pathways.

Posted by lalitree on October 27, 2004 08:31 PM | Permalink to Comment

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