Notes on the Structure of Ophioglossuin. 193 



O. macrorhizu)n, Kze, has a diarch bundle, like that of O. 

 Bergianum. 



B. — Rhizome. 



The epidermis is present in limited places. Holle found 

 none in vulgatum. No cork was present in pedunculosuin or 

 vulgatum. Russow found it abundant, and Holle found some 

 in vulgatum. There is a vascular net work in the rhizome, and 

 the vascular bundle from leaf or root incorporates itself in 

 this network. I could not demonstrate a direct connection be- 

 tween each leaf and a corresponding root, as Holle was able 

 to do. Indeed, I could find no comparison in number or 

 position between the leaves and roots, and was unable to draw 

 Holle's conclusion from his own drawings from nature. Reticu- 

 lated vessels were present in the rhizome. The rhizomes of 

 lusitanicum, Bergianum^ macrorhizum, and pendulum had the 

 structure of that of pedunculosum. 



C. — Leaf. 



The structure in pedunculosum., lusitanicum, reticulatum, and 

 7nacror/iizum, was like that of vulgatum. In Bergianum the ex- 

 ternal wall of the epidermal cells is much thickened. The 

 edges of the leaf are thick, the structure compact, and the 

 stomata small. The whole structure of the leaf suggests its 

 habitat; viz., the dry climate of S. Africa. 



In pendulum the phloem has very thick walls and surrounds 

 the xylem. The latter is in a zone running through the cen- 

 ter of the circle formed by the phloem and abutting on it at 

 each end. The space on each of the xylem, between it and 

 the phloem, is filled with parenchyma. This arrangement is 

 replaced by the ordinary one in the lower part of the leaf and 

 in the petiole. 



D. — Spike. 



In pedunculosum, a special preparation is made in the tissue 

 for the dehiscence of the sporangium. \n pedunculosum, lusitani- 

 cinn, Bergianum, macrorhizum, palmatum, Surinamense, rcticula- 

 turn, and bulbosum, the sporangia show no trace of a division 

 into two compartments. 



In vulgatum there is an incomplete wall extending from the 

 axial side of the sporangium, parallel to the axis of the spike. 

 It presents a bow-shaped edge toward the exterior, being far- 

 ther extended at the upper and lower ends than in the middle. 

 In pendulum this division wall is usually nearly complete, and 



