1903 9 63 It thus appears that 33.3 per cent of the N[orth] A[merican] Coniferæ (genera) are wholly devoid of ray tracheids.
1956 F. W. Jane v. 91 Ray tracheids often form the marginal cells of the rays.
2001 11 193/2 The presence or absence of fusiform rays, spiral thickenings, and ray tracheids were used to determine the species of otherwise indistinguishable woods.