The vascular tissue of a _Lyginopteris_ root (fig. 410) consists of from three to eight alternate strands of centripetal xylem and phloem, and with the metaxylem is associated a small amount of conjunctive parenchyma which does not form a central pith. The pericycle, one to several layers broad, is succeeded by an endodermis which occasionally shows the characteristic thickenings on the radial walls. A broad cortex of thin-walled lacunar tissue with numerous secretory cells is bounded externally by a superficial cylinder of two or more layers of comparatively large and thin cells, the outermost of which are radially elongated. This superficial tissue forms a striking feature by which a _Lyginopteris_ root may often be recognised at a glance. The root represented in fig. 410, approximately 2 mm. in diameter, has a heptarch stele divided into seven xylem-groups by crushed bands of parenchyma and a protoxylem strand occupies the apex of each projecting angle (fig. 410, _px_). The superficial cylinder of clear cells is seen at _a_. A very small root is seen at _r_ in fig. 410. [Illustration: Fig. 410. _Lyginopteris oldhamia_, young root. × 30. (Kidston Coll. 403.)] Fig. 415, C, represents part of an older root in which the pentarch primary xylem is enclosed by broad wedge-like groups of secondary xylem and phloem separated by conspicuous medullary rays opposite the protoxylem strands (_px_). Crushed primary phloem arcs, _p_, are often clearly recognisable beyond the cambium. The secondary thickening, as Williamson and Scott state, ‘takes place exactly in the manner typical of roots of Dicotyledons, so that this fossil might very well be used for purposes of demonstration as illustrating the secondary growth of a root with diagrammatic clearness’[201]. The young roots of _Lyginopteris_ resemble in many respects those of Marattiaceous Ferns, though the presence of a single apical cell, if such occurs, is a distinguishing feature; but in the presence of secondary conducting tissue they agree with those of Phanerogams. _Distribution of Lyginopteris._