12 The Nature and Origin of Stipules. 



branches arise they enter the margins of the petioles or the inter- 

 foliar portions of connate leaves. In Platanus and Liriodendron 

 with alternate leaves, each of which receives seven vascular bun- 

 dles, a similar girdle is shown to pass around the stem posterior 

 to the leaf, and is there joined by another small leaf-trace bundle. 

 From this girdle arise a part of the stipular veins, the others being 

 branches of the sixth and seventh leaf-trace bundles. 



Clos, D.—Sepales Stipulates. Bull. Soc. Bot. Fr. 6: 580-589. 1859. 



It is argued from the similarity of the sepals to the divisions 

 of the involucre (stipulium) and also to the stipules of the fully 

 developed foliage leaves which is frequently observed, that they 

 represent stipules. This is held to be true in many Geraniaceae, 

 Malvaceae, Begoniacese and Cistaceae. In concluding Clos adds 

 the theoretical consideration that " whether or not stipules are 

 admitted to be organs different from the leaf, analogy seems to 

 demand that in some cases at least they should participate in 

 some degree in floral formation." 



Cosson, E.— Note sur la Stipule et la Prefeuille dans le Genre Potamo- 

 geton. Bull. Soc. Bot. Fr. 7: 715-720. 1860. 



u The stipule in Potamogeton is very closely like the first leaf 

 of one of the branches. It is homologous with the ligule of the 

 Granrineae and Cyperaceae and is constituted by a single organ, 

 not by two united by their margins." 



Eicliler, A. W.— Zur Entwicklungsgeschicbte des Blattes. 22-31, 1861 

 (Cited by Martin Franke in Bot. Zeit. 54 :45. 1896.) 



Stipules are said to arise without exception as a product of the 

 leaf base of the primordial leaf. This mode of origin of the 

 stipules is their chief characteristic. Their form, their more or 

 less foliaceous condition and their persistence are secondary. 



In individual leaf development in the Stellatae, the whorl 

 originates in a uniform ring about the growing point. Then arise 

 two opposite prominences in the ring. These develop into the 

 true leaves. After them appear two smaller prominences on each 

 side of the stem between the first. These are the stipules. Ac- 

 cording to the species they develop separately, forming six-leaved 

 whorls, or grow together giving origin to four-leaved whorls.* 



*With this view Gobel agrees (Schenk's Handbucb der Botanik 3 : 230. 

 1884), except that he does not distinguish the time of appearance of the differ- 

 ent parts of the whorl. 



