THE YOUNG SPOROPHYTE 



57 



the first three or four leaves were sterile and practically like the cotyledon, and it 

 is not certain which leaf, under ordinary circumstances, first gives rise to the spore- 

 bearing spike. In O. moluccanum and the other tropical species of Ophioglossum 

 growth is continuous, and it is evident that the development of the leaves does not 

 take the long period required in O. vulgatum and other species of temperate regions, 

 where growth is interrupted each year and where only one leaf is developed in the 



v^SSv 



Fig. 38. 



Six of a snirs nl transverse sections of a young sporophyte of Ophioglossum moluccanum, etill attached to primary 

 root, r. Section B passes through the stem apex. X35. 



season. Mettenius states that O. pedunculosum, which, as we have seen, may per- 

 haps be identical with 0. moluccanum, develops three leaves each season. This 

 was in'^the Botanical Garden at Leipzig, and it is highly probable, under the 

 much more favorable conditions of its native tropical habitat, that this number 

 would be exceeded. There was not time to make investigations in regard to this 

 r point, but it is very certain 



that several leaves are de- 

 veloped in the course of each 

 year and that the develop- 

 ment of the individual leaf 

 does not require the long pe- 

 riod necessary in the species 

 of cold climates. 



Figures 38 and 39 show 

 several transverse sections 

 forming a series taken from 

 a young sporophyte with 

 three fully developed leaves 

 and two younger ones. This 

 bud was developed from a 

 small root, but it was not 

 certain that this was the 

 primary root of the embryo. 

 The spirally arranged leaves 

 show the two-fifths diver- 

 gence. The second and 

 third leaves of this bud 

 were successively larger than the first leaf, but the section of the petiole showed 

 a single centrally placed vascular bundle of the same type as that of the primary 



Fig. 39. 



A. Section of the sporophyte shown in fig. 38, showing arrangement of leaves; 



r is the primary root. X about 60. 



B. Vascular bundle of first leaf, more highly magnified. 



C. Stem apex, showing youngest leaf trace, / s ; st, apical cell of stem. 



