AN EXTINCT PLANT OF DOUBTFUL AFFINITY. 431 



Root. — As regards the roots of this genus we have but 

 little information. Renault 1 has figured a small silicified ex- 

 ample from Autun, with a diameter of 2 mm. In the 

 centre there appears to be a diarch primary xylem bundle, 

 surrounded by concentric rows of reticulately pitted trac- 

 heicls. It is possible that two specimens figured by Felix, 2 

 may representadventitiousrootsbeinggiven off from a.Sphc/10- 

 phyllum stem. He speaks of them as examples of lateral 

 branching, but their precise nature is, by no means, very 

 easy to determine. 



Fructification. — The fructification of Sphenophyllum as 

 first described by Williamson and Zeiller, 3 may be 

 thus defined : — An axis traversed by a triangular strand of 

 primary xylem tracheids, bearing at intervals of 1 "5 to 

 2 - 5 mm. similar leaf verticils consisting of a number of 

 linear lanceolate segments, fused in their lower portions 

 into an open funnel-shaped disc. The numerous sporangia 

 occur in 2 to 4 concentric circles on the upper surface of 

 each disc, in radial sections of a cone presenting the appear- 

 ance of a row of 2 to 4 sporangia between each whorl of 

 bracts. Each sporangium is attached to a slender stalk 

 springing from the upper surface of the leaf disc, and 

 terminates in a hooked tip facing the axis of the strobilus, 

 thus resembling the attachment of an anatropous ovule to 

 its funicle. Each sporangiophore possesses a strand contain- 

 ing a few xylem tracheids. At the point where the stalk or 

 sporangiophore passes into the sporangium, the epidermal 

 cells have thicker walls, and appear to represent an annulus, 

 the sporangia dehiscing by a longitudinal slit on the side 

 away from the stalk. The sporangia are isoporous, and the 

 spores have a reticulately marked outer membrane. 



In a recent paper by Count Solms-Laubach 4 an exceed- 

 ingly interesting addition is made to our knowledge of the 

 Sphenophyllum strobilus. While confirming in the main 

 the results arrived at by Zeiller, Williamson, and Scott, he 

 describes a new type of fructification from the neighbour- 



1 Renault (1), pi. viii., fig. 5 ; and (2), pi. xv., fig. 6. 



2 Felix, pi. vi., figs. 2 and 7. 



3 See " Science Progress," vol. i., p. 54. 4 Solms-Laubach. 



