Elm 28:1 Pine 66:1

Lime 37:1 Douglas fir 77:1

Oak 47:1 Larch 113:1

The protein content of tree leaves is very similar to their ratio of
carbon (C) compared to nitrogen (N)

Sometimes plants store food in the form of oil, the most
concentrated biological energy source. Oil is also constructed from
sugar and is usually found in seeds. Plants also build structural
materials like stem, cell walls, and other woody parts from sugars
converted into cellulose, a substance similar to starch. Very strong
structures are constructed with lignins, a material like cellulose
but much more durable. Cellulose and lignins are permanent. They
cannot be converted back into sugar by plant enzymes. Nor can most
animals or bacteria digest them.

Certain fungi can digest cellulose and lignin, as can the symbiotic
bacteria inhabiting a cow's rumen. In this respect the cow is a very
clever animal running a cellulose digestion factory in the first and
largest of its several stomachs. There, it cultures bacteria that
eat cellulose; then the cow digests the bacteria as they pass out of
one stomach and into another.

Plants also construct proteins, the vital stuff of life itself.
Proteins are mainly found in those parts of the plant involved with
reproduction and photosynthesis. Protein molecules differ from
starches and sugars in that they are larger and amazingly more