44 



THE OPHIOGLOSSALES 



The second root arises quite independently of the stem apex, being developed 

 below the insertion of the primary root, and its vascular bundle joins that of the 

 first root near its base. 



A rudimentary vascular bundle is developed within the cotyledon, and also 

 joins the bundle of the main root near its base, but no bundle at all is developed 

 within the stem. The cotyledon reaches only a very small size, but the second leaf 

 soon appears nearly opposite the cotyledon. 



The second leaf also develops at an early period a vascular bundle, which 

 connects with the vascular bundle of the primary root near its point of junction with 

 the second root, and this exactly resembles the arrangement of the bundles in the 

 bud formed upon the root in O. moluccanum. It is evident that in the young sporo- 

 phyte of 0. vulgatum, as in 0. moluccanum, the vascular system is made up entirely 

 of the bundles of the roots and leaves, the stem itself having no proper stele. 



The second leaf finally emerges and appears above ground as the first sterile 

 green leaf of the young sporophyte. Bruchmann states that the second leaf does not 

 appear above ground until five years after it is first formed, and he believes that the 

 sporophyte, at the time its first leaf appears above ground, is nine to ten years of age. 



The third leaf may be fertile, but this is not always the case. 



THE ANATOMY OF THE YOUNG SPOROPHYTE OF OPHIOGLOSSUM. 



In Ophioglossum pendulum the young primary root soon breaks through the 

 prothallium and elongates rapidly, but owing to its brittleness it is easily broken 

 off, and it is impossible to state here just how far it develops before the bud is 

 formed upon it. The development of the second root varies a good deal. The first 

 root may reach a length of 3 or 4 centimeters before the second root can be seen 

 at all. The growth of these earlier roots is in all respects similar to that of the later 

 ones. There is a large tetrahedral apical cell whose divisions are quite regular, 



and there is soon visible the axial vascular 

 bundle which extends for some distance 

 into the foot, where it ends blindly. The 

 vascular bundle of the second root joins 

 the first at the junction of the latter with 

 the foot (fig. 21, D). 



The first tracheary tissue appears at 

 the point of junction, and is made up of 

 short, somewhat irregular, pointed tra- 

 cheids with reticulate thickenings. From 

 this point the development of the tracheary 

 tissue proceeds toward the apex of the roots. 

 The bundle is diarch, as is plainly seen in 

 cross-sections (fig. 27, £) . The endodermis 

 is very clearly defined and the characteristic 

 radial markings are extraordinarily clear, 

 especially in sections treated with a double 

 stain of safranine and gentian violet. The 

 tracheary tissue is also beautifully differen- 

 tiated by this stain. The bundle is slightly 

 elliptical in form and the protoxylem ele- 

 ments appear at the foci of the elliptical 

 section. The first appearance of the tracheary tissue is some distance back of the 

 apex and the development proceeds rather slowly. In thg oldest part of the roots 



Fig. 26. 



A. Longitudinal section of an older bud of Ophioglossum 



moluccanum. X50. i/,stem apex;/' first leaf of 

 bud; r', first root of the bud. 



B. Stem apex of same. X90. 



