Summary(1)Aletrisis a liliaceous genus with both American and Asiatic species, all of which possess a rhizome bearing tough, wiry, adventitious roots.(2) The roots are characterized by the peculiar nature of the surface‐layer, all the cells being elongated radially and forming a closely‐set system of papillae.(3) The root endodermis is composed of elongated cells with pointed ends similar to prosenchymatous fibres. These develop extremely heavy thickenings of lignocellulose.(4) There are a few isolated passage‐cells in the young root, but they develop the tertiary condition a short distance behind the root‐tip.(5) In old roots all the tissues external to the endodermis are frequently exfoliated.(6) The metaxylem vessels inAletris farinosapossess scalariform perforations between the vessel segments.(7) There is evidence that in the various species ofAletristhere is a series of transitional stages from the scalariform perforation to the ring type.(8) An examination of herbarium material suggests that the root anatomy may be of value in differentiating between the various