2006-11-02 13:10:07 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Botany
The pine needles are lacking the pigments, anthocyanin, xanthophyll, and carotene which give the flat leaf trees their fall colors. Pine needles are constructed to prevent them from freezing during the cold winter months. They will eventually lose their chlorophyll and turn brown due to an accumulation of tannic acid.
2006-11-06 07:42:36 · answer #1 · answered by ATP-Man 7 · 0⤊ 0⤋
Leaves changing color is only seen in deciduous trees. There are actually a few deciduous conifers (dawn redwood, larches) whose needles change color (to yellow). The colors you see in fall are actually due to pigments and sugars that are there all along, but masked by the green from all the chlorophyll in active leaves. Once deciduous leaves get ready to fall, they stop producing chlorophyll. Since conifer leaves (needles) photosynthesize until they die, they don't have a period between when they have stopped producing chlorophyll and when they fall.
2006-11-02 23:29:04 · answer #2 · answered by candy2mercy 5 · 0⤊ 0⤋
It has to do with leave size, temperature and sap.
as temp drops, trees moves the sap to the root. Lack of sap (tree blood) cause the leaves to die and fall. Conifers needles are not affected by temp changes so the tree sap stays and the needle are kept alive (green).
2006-11-02 21:19:17 · answer #3 · answered by Manny L 3 · 1⤊ 0⤋
they're conifers or evergreens. They'll turn brown and die.
2006-11-02 21:15:08 · answer #4 · answered by astronomychica 3 · 1⤊ 0⤋
because they stay on the tree all year long
2006-11-02 21:41:47 · answer #5 · answered by J 3 · 0⤊ 0⤋
they're pine needles & they turn brown when dead
2006-11-02 21:11:48 · answer #6 · answered by Anonymous · 0⤊ 0⤋