

BULBILS OF LYCOPODIUM LUCIDULUM 



■ 



R. Wilson Smith 



(with TWENTY-ONE figures) 



It is well known that certain species of Lycopodium belonging 

 to that subdivision of the genus which is characterized by the non- 

 strobilar arrangement and slight differentiation of the sporophylls 

 produce organs of vegetative reproduction known as bulbils or 

 gemmae. These organs are of a peculiar type, so unlike anything 

 else in the plant kingdom that the question of their morphological 

 nature is a very puzzling one. Various opinions have been held. 

 They have been interpreted as equivalent to sporangia, to lateral 

 branches in the axils of leaves, to lateral branches without support- 

 ing leaves, to reduced branches resulting from dichotomy of the 

 stem apex and gradually displaced, and to the bulblets of certain 

 ferns and monocotyledons. 



We owe the first accurate account of the development of the 

 bulbils to Hegelmaier (4). He corrected the view previously 

 held that they originate in the axils of preexisting leaves, and 

 showed that they take the place of leaves in the phyllotactic 

 spiral. He could find no means of distinguishing very young 

 leaves and bulbils in longitudinal sections; and a view of the apex 

 of the plant showed a difference only when the larger size indicated 

 that a bulbil was beginning to develop. 



Strasburger (10) gave a short description of the bulbils, 

 differing from Hegelmaier's in some respects. In the following 

 year, after further investigation (n), he confirmed the interpreta- 

 tion of Hegelmaier in every detail but one; he thought leaves 

 and bulbils differ somewhat in their mode of development. By 

 special manipulation of the stem tips, he selected for study those 

 tips on which young bulbils were present. In these young bulbils, 

 when viewed in longitudinal section, he thought he could detect 

 a middle apical group of two cells in the dermatogen. This account 

 does not contradict that of Hegelmaier, for Strasburger really 

 found no difference between leaves and bulbils until the latter 



Botanical Gazette, vol. 69] 



[426 



