C
|
O

_Fisetin_, found in quebracho wood and fiset wood,

O ____OH
HO / \ / \ __/ \OH
| | | \_____/
| | |
\ / \ /
C
|
O

_Quercitrin_, found in oak bark, horse-chestnut flowers, and in the skin of
onions,

O ____OH
HO / \ / \ __/ \OH
| | | \_____/
| | |OH
\ / \ /
HO C
|
O

_Morin_, found in yellow wood (_Morus tinctoria_).

O HO____
HO / \ / \ __/ \OH
| | | \_____/
| | |OH
\ / \ /
HO C
|
O

_Gentisin_, found in yellow gentian (_Gentiana lutea_),

O
CH_{3}O / \ / \ / \
| | | |
| | | |
\ / \ / \ / OH
HO C
|
O

As a rule, the most brilliant of these yellow pigments are found in the
largest quantities in the bark and wood of various species of tropical
plants; although they are also present, in smaller amounts, in the blossoms
of species growing in temperate zones.

The anthoxanthins are easily converted into anthocyanins, and _vice versa_,
by the action of oxidizing and reducing enzymes which are commonly present
in the tissues of the plants which develop the pigments.

THE PRODUCTION OF ORNAMENTAL PIGMENTS IN FLOWERS, ETC.

The breeding of flowering plants having blossoms of almost any desired
color has become a commercial enterprise of large importance. The results
which have been obtained, in many cases, have been made the object of