The flavans are

benzopyran Benzopyran is a polycyclic organic compound that results from the fusion of a benzene ring to a heterocyclic pyran ring. According to current IUPAC nomenclature, the name chromene used in previous recommendations is retained; however, systemati ...

derivatives that use the 2-phenyl-3,4-dihydro-2''H''-chromene skeleton. They may be found in plants. These compounds include the

flavan-3-ol Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of comp ...

flavan-4-ols The flavan-4-ols (3-deoxyflavonoids) are flavone-derived alcohols and a family of flavonoids. Flavan-4-ols are colorless precursor compounds that polymerize to form red phlobaphene pigments. They can be found in the sorghum. Glycosides (abacopter ...

and

flavan-3,4-diol Leucoanthocyanidin (flavan-3,4-diols) are colorless chemical compounds related to anthocyanidins and anthocyanins. Leucoanthocyanins can be found in ''Anadenanthera peregrina'' and in several species of ''Nepenthes'' including ''Nepenthes burbidgea ...

s (

leucoanthocyanidin Leucoanthocyanidin (flavan-3,4-diols) are colorless chemical compounds related to anthocyanidins and anthocyanins. Leucoanthocyanins can be found in '' Anadenanthera peregrina'' and in several species of '' Nepenthes'' including '' N. burbidg ...

). A ''C''-glycosidic flavan can be isolated from

cocoa liquor Chocolate liquor (cocoa liquor) is pure cocoa mass (cocoa paste) in solid or semi-solid form. Like the cocoa beans (nibs) from which it is produced, it contains both cocoa solids and cocoa butter in roughly equal proportion. It is produced f ...

. ''

Casuarina glauca ''Casuarina glauca'', commonly known as the swamp she-oak, swamp oak, grey oak, or river oak, is a species of ''Casuarina'' native to the east coast of Australia. It is found from central Queensland south to southern New South Wales. It has becom ...

'' is an

actinorhizal plant Actinorhizal plants are a group of angiosperms characterized by their ability to form a symbiosis with the nitrogen fixing actinomycetota ''Frankia''. This association leads to the formation of nitrogen-fixing root nodules. Classification Actinor ...

producing root nitrogen-fixing nodules infested by ''

Frankia ''Frankia'' is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the ''Rhizobium'' bacteria found in the root nodules of legumes in the family Fabaceae. ''Frankia'' also initiate the forming of root ...

''. There is a regular pattern of cell layers containing flavans.

References

{{Aromatic-stub