The main device (symbol) in the O’Flanagan blazon is the oak tree. The two main tinctures (colors) are vert and argent.
The deep green colour that is so often observed in heraldry is more properly known as vert. According to Wade, the use of this colour signifies “Hope and Joy”, but may also represent, rather delightfully, “Loyalty in Love” 1The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P36. It has other names also, the French call it sinople, perhaps after a town in Asia Minor from where the best green die materials could be found 2A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1894, Entry:Vert. More fanciful heralds liked to associate it with the planet venus and the precious stone emerald 3Boutell’s Heraldry, J.P. Brooke-Little, Warne, (revised Edition) London 1970, P 27. More strangely, there is some evidence that the term prasin was anciently used, being the Greek for the vegetable we call the Leek!
Argent is the heraldic metal Silver and is usually shown as very pure white. It is also known more poetically as pearl, moon (or luna) 4Understanding Signs & Symbols – Heraldry, S. Oliver & G. Croton, Quantum, London, 2013, P53. In a sketch or drawing it is represented by plain, unmarked paper 5A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1847, P11.
Amongst the natural objects depicted on a coat of arms, trees feature frequently, either in whole or as individual branches and leaves. 6A Complete Guide to Heraldry, A.C. Fox-Davies, Bonanza (re-print of 1909 Edition), New York, 1978, P94, 262, 407. Although sometimes described simply as a tree most often the specific species was named, and the oak tree or oak leaf is a typical example that frequently is depicted in arms, sometimes fructed with acorns of a different colour. 7A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1894, Entry:Oak For good reason, Wade assigns the meaning of “antiquity and strength” to this symbol. 8The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P126