40 



THE OPHIOGLOSSALES 



developed at an early period. The stele of the second root joins that of the first 

 where the latter joins the foot (fig. 2i, D). The primary root in 0. pendulum is, 

 usually at least, diarch. 



DEVELOPMENT OF THE PRIMARY BUD IN OPHIOGLOSSUM MOLUCCANUM. 



The several terrestrial species of Ophioglossum growing at Buitenzorg and 

 associated under the name 0. moluccanum differ strikingly from 0. vulgatum in the 

 further history of the young sporophyte as well as in the early development of the 

 first functional leaf. This difference is also found in the young sporophyte of 0. 

 reticulatum (t) collected at Hakgala in Ceylon. All of these tropical species agree 

 with O. pedunculosum, which was correctly described by Mettenius (Mettenius 1), 

 in the origin of the definitive axis which arises as an adventitious bud from the 

 primary root of the young sporophyte. A similar condition of things probably is 

 true also in O. pendulum, although in the latter no leaf is at first developed from the 

 young sporophyte, which is composed exclusively of one or two roots in addition to 

 the foot, so that the first leaf in O. pendulum is also an adventitious structure. 

 Whether or not the primary leaf in O. pendulum, and probably at the same time the 

 stem apex, arises as a bud from the primary root, or whether (which seems more 

 likely) it is developed from a secondary root, can not be stated, as no young leafy 

 buds were found in connection with the gametophyte. 



Fig. 24. — Ophioglossum moluccanum. 



A. Tangential section of primary root, showing young, endogenous bud, b. X about 50. 



B. C. Two sections of the same bud. B, the first leaf; C, stem apex. Xico. 



D. Two transverse sections of a young bud; i passes through stem apex st; 2, through leaf. 



Mettenius gives no detailed study of the development of the bud upon the root, 

 nor does he state whether he recognized its endogenous origin. The bud arises 

 much in the same way that a secondary root does, and is not visible upon the out- 

 side of the root until it is far advanced in its development, the young leaf breaking 

 through the overlying tissues in much the same way that a young root emerges. In 

 two instances the rudiment of the young bud could be seen close to the apical 

 meristem of the root, in a position which is exactly the same as that described for the 

 leafy buds formed at the apex of the root in O. vulgatum. More commonly, the 

 bud originated nearer the base of the root, but it may arise at any point between 

 the base and the apex. Figure 24 shows sections of the youngest buds that were 

 found, y^ is a tangential section of the primary root, in which the young bud has 

 formed at a pomt not very far back from the root apex, r. The first leaf of the young 



