Pine Bread

I'm currently reading "Origin" by Stephen Baxter. I never bought it as a "survival read" but it does mention PSK's and the story revolves round a survival situation.
I was curious about a paragragh that mentioned making bread from pine trees. Here's the quote, has anybody heard of this or tried it?

"You could make rope for instance, from birch bark, pine roots or willow. Women baked pine bread made from phloem, the soft white flesh just inside the trees bark. You could drink the sap of birch if you had to."

EDIT
Heres the book and a few reviews:
http://tinyurl.com/2h9vo

Yes you can. There are countless plants which are edible and can be processed into flours. One of the great dangers of commercial agriculture is the ever shrinking reliance on a few staples such as wheat and rice, and only a few varieties of those. Native plants and heirloom cultivated varieties are a treasure of nutrition, adaptability and alternate resources.

Reminds me of old TV commercial for Grape-nuts cereal -- Euell Gibbons asking viewers if they had ever eaten a pine tree "most parts are edible".

Yeah, know what you mean.
Its a strange rambling sort of book with a very distinctive style and subject matter. If you read some of the reviews its not exactly to everyones taste, but I'm quite enjoying it - I've certainly read worse.