Pine nuts. They are borne on the scales of
pine cones, and like the coconut, are mainly
endosperm tissue rather than cotyledons.
Like its cousins the pecan and hickories,
the walnut is the stone of a thin-walled fruit,
the edible portion being two lobed, wrinkled
cotyledons. Walnuts are exceptionally rich in
the omega-3 polyunsaturated linolenic acid,
which makes them nutritionally valuable but
also especially liable to become rancid; they
should be kept in the cold and dark. The
aroma of walnuts is created by a complex
mixture of molecules derived from the oil
(aldehydes, alcohols, and ketones).
Walnut Relatives A North American relative
of the Persian walnut, the black walnut (J.
nigra) is smaller, with a harder shell and a
stronger, distinctive flavor. It was once