According to The Celtic Connection at Wicca.com, The Reed tree also known as Ngetal, is the sacred tree from 0ct 28-November 24.
Ngetal- as an Ogham means Harmony, unity and wisdom. The symbol for this is 3 diagonal parralel lines with a straight line through the center
For those curious as to what an Ogham is it is the Celtic alphabet of one of the Irish runic languages. It was the alphabet used prior to the ninth century by ancient Irish and other Celtic nations.
“The oghams seem to have been merely tree-runes. The Irish regarded the oghams as a forest, the individual characters being trees (feada), while each cross-stroke is called a twig (fleasg).” —Isaac Taylor: The Alphabet, vol. ii. chap. viii. p. 226. Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
The ancient Druids were said to be able to talk to eachother with their hands using the Ogham to keep their conversations secret from outsiders.
For me being of Celtic descent I find these little historical snypets to be fascinating.