tree, leaves may hang on the stem for just a few days or remain for
several weeks.
This biological process, of abscising leaves for winter survival
and to prepare for the spring's new foliage, is the reason we enjoy
fall foliage color. With the absence of water, the leaf stops
photosynthesizing and loses its green color from chlorophyll and
instead reveals hidden chemical colors. Xanthophyll, a bright-yellow
pigment, becomes clearly visible. Another substance called carotene
(carrots contain this chemical in quantity) is brilliant with red or
orange hues. Deep reds and purples are created by anthocyanin , a
chemical that is newly formed upon the departure of chlorophyll.
The fall color of a tree depends on which of the three compounds
it has in the greatest abundance within its leaves. Birch, ginkgo and
elm turn yellow with xanthophyll. The Sugar Maple turns golden,
bright orange, or red with carotene. Liquidambar and ash turn deep
red or purplish from anthocyanin production. Frequently, multiple
presences of these chemicals will yield combinations of colors within
the leaf.
* * *
Sadly, I wasn't able to have that conversation with Fritz. He had
passed away a week earlier. Angry with myself, I thought about him as
I spotted a liquidambar leaf fall slowly, first end over end, then in
a spiral as it flipped lazily toward the ground. It joined its
brothers and sisters that already carpeted half of the sidewalk with
a brilliant yellow. I know that Fritz would have hoped that the city
gardeners wouldn't tidy up too soon. See you next time.
* STEVE KAWARATANI is the owner of Landscapes by Laguna Nursery,
1540 S. Coast Highway in Laguna Beach. He is married to local artist,
Catharine Cooper, and has three cats. He can be reached at 949 497
2438, or E-mail to plantm@lagunanursery.com.
