The Nature and Origin of Stipules. 45 



show how small is the real difference between the various stipular 

 forms. Not all stipules possess supporting tissues but, just as is 

 the case in the ligule of most grasses, msxy be without any fibro- 

 vascular bundles whatever. This is the case in Vitis, in Partheno- 

 cissus and Hydrocotyle. Vitis Labrusca L. (fig. 73) shows a 

 somewhat thickened central streak at the base of the membranous 

 stipule, but in Hydrocotyle Americana L. (fig. 74), the thickness 

 is uniform and the stipule very thin. These facts give some au- 

 thority to the supposition that the pectinate interpetiolar appen- 

 dages which occur in the Composite Willoughbya scandens (L.) 

 Kuntze (fig. 75) are true stipules. They are hyaline in texture, 

 without supporting tissue, and may possibly be merely of epider- 

 mal origin. To determine this point requires opportunity to ex- 

 amine their development. 



It is of importance to state that the tendril of the Cucurbita- 

 ceae, regarded by many as a stipule, has been determined by ana- 

 tomical examination to represent the first leaf of the axillary 

 bud.* The spines of Xanthium spinosum L., simulating stipules 

 in position, are degenerate pistillate flowers. As proof of this, 

 they often bear a greater or less number of hooked prickles like 

 those of the flowers, and there may be a spine on one side and a 

 flower on the other, showing them to be of the same significance. f 



The stipules of Gomptonia peregrina (L.) Coulter (fig. 76) de- 

 nied by some to be properly so-called, do not differ anatomical^ 

 from other stipules notwithstanding their peculiar morphology, 

 and are to be included under the term. One of the chief reasons 

 for their exclusion seems to have been the absence of stipules in 

 Myrica. This is doubtless a case parallel with that of Viburnum, 

 of which most of the species have lost their stipules by degener- 

 ation. 



While it is not a generally accepted view, there is no good reason 

 why stipules should not sometimes be distinguishable in floral 

 parts. They are clearly present in the sepals of Rosa and Rhodo- 

 typus, and the smaller intermediate lobes of the calyx of Potentilla 

 probably represent pairs of united stipules, one from each neigh- 

 boring calyx-lobe in the manner of interpetiolar stipules. \ The 

 teeth of the filament in Deutzia are very suggestive of stipules in 



*See Lestiboudois, Bull. Soc. Bot. Fr. 4: 746-747. 1857. Cited on p. 6. 

 t See also Clos. Mem. Acad. Sci. Toulouse, (IV), 6: 66-75. 1875. 

 % See Engler and Prantl. Pflanzen Familien. 3: Abt. 3, 6. 1894. 



