Try: openplotmat() pos <- coordinates(c(2,4),hor=FALSE) Parr<- treearrow(from=pos[1:2,],to=pos[3:6,],arr.side=1:2,path="V") text(Parr,"hello") dr. Karline Soetaert NIOO - CEME PO box 140 4400 AC Yerseke the Netherlands Phone: ++ 31 113 577487 fax: ++ 31 113 573616 e-mail: k.Soetaert at nioo.knaw.nl http://www.nioo.knaw.nl/users/ksoetaert