From: G&P
Message: 62912
Date: 2009-02-08
Pokorny (the big book on all this) lists cognates in Greek, Latin (culmus), Germanic, Baltic and Slavic. He says that the Old Irish kaláma- (a reed or quill for writing?) and the Welsh calaf are borrowed. He does suggest a possible connection with words for “spear”: mid Irish cail, celtair, Greek ke:lon.
Calaf is probably borrowed.
Peter