tracheids bụ elongated mkpụrụ ndụ na lignified nke abụọ thickening nke cell mgbidi, pụrụ iche maka conduction nke mmiri, na mbụ pụtara na osisi n'oge ha mgbanwe ka ala na Silurian oge ihe karịrị 425 nde afọ gara aga (lee Cooksonia). The nwere xylem tracheids akọwa vascular osisi ma ọ bụ Tracheophytes. Tracheids na-apụta, elongated xylem mkpụrụ ndụ, ndị kasị mfe cell nke nwere na-aga n'ihu isi mgbidi na lignified nke abụọ mgbidi thickening n'ụdị yiri yiri mgbaaka, hoops, ma ọ bụ reticulate netwọk. More mgbagwoju tracheids na valve-dị ka valves na-akpọ pnosperytes akara akara ókè-ala. The xylem gymnosperytes na ndị ọzọ na-agba ọsọ na mmiri na-dị nnọọ dị ka mgbidi nke osisi.
Tracheophytes