The Nature and Origin of Stipules. 7 



From these considerations Agardh concludes that there are two 

 kinds of appendicular organs instead of one, namely stipules and 

 leaves. 



Astaix. — Essai sur la Theorie des stipules, these de l'Ecole de pharmacie 

 de Paris. 1-25. 1841. (Cited by Clos in Bull. Soc. Bot. Fr. 1 : 302. 1854. ) 



The conclusion is reached that the leaf is not a primitive ap- 

 pendage of the stipule and that the stipule is nothing more than 

 an appendage of the leaf. 



Kegel, E. — Beobachtung uber den Ursprung und Zweck der Stipeln. 

 Linnsea, 17: 193-234. 1843. 



Regel has studied the development of stipules in seedlings and 

 in the growth of individual leaves. He believes, but does not 

 feel ready to assert, that stipules are present in all Angiosperms in 

 the earliest stages of growth. He therefore includes in stipular 

 formations the ligule, ochrea, sheathing petiole and the supernu- 

 merary leaves of the Stellatse. He concludes from his observa- 

 tions : 



1. "That all the leafy organs of phanerogamic plants are di- 

 vided into two entirety distinct formations, the stipular and leaf- 

 formations. 



2. " That the stipular formation arises from the base of the 

 meristem tissue of the leafy axis, covering the summit, but always 

 with a longitudinal cleft or one passing transversely across the 

 apex. 



3. " That perfect stipules are formed by the occurrence of two, 

 four or more clefts in the original stipular sheath, giving rise to 

 as many stipular leaflets. 



4. " That the stipules receive their vascular bundles directly 

 from the stem, and are usually parallel veined because of their 

 forming originally a completely encircling sheath. 



'5. " That they serve always for the protection of the growing 

 point and of the true leaves, when these are present, during their 

 development. 



6. " In all plants, organs adapted for protection belong not to 

 the leaf-formation but to the stipule-formation. 



7. " That stipules are to be regarded as a formation preceding 

 the leaf- formation, since they appear before the leaves. 



8. " That they belong primarily to a nodal ring distinct from 

 that producing the leaves and situated either above or below it. 



