DICOTYLEDONS. 639 



with the internode. On a vegetative shoot at least one lateral shoot is produced 

 in the axil of each leaf, although only a few of the axillary buds unfold. Sometimes 

 other axillary buds are produced in rows above the original one ; as, for instance, 

 above the axils of the foliage-leaves in Aristolochia Stpho, Glediischia, Lonicera, &c.^, 

 above the axils of the cotyledons in Juglans regia, and that of the larger cotyledon 

 in Trapa. In woody plants the axillary buds destined to live through the winter 

 are not unfrequently so completely surrounded by the base of the leaf-stalk that 

 they are not visible until the leaf has fallen off, as in Rhus typhtnum, Virgilia lutea, 

 Platanus, &c., and are then called Inirapetlolar Buds. Besides the ordinary axillary 

 branching, some cases are known among Dicotyledons of lateral and monopodial 

 but extra-axillary branching. To this description belong the tendrils of Vitis and 

 Ampelopsis which are produced (according to Nageli and Schwendener) beneath the 

 punclum vegetationis of the mother-shoot, opposite to the youngest leaf and somewhat 

 later than it. In Asclepias syriaca and some other plants a lateral vegetative branch 

 stands beneath the terminal inflorescence between the insertions of the foliage-leaves, 

 which themselves also produce shoots in their axils. According to Pringsheim^ 

 lateral shoots arise on the concave side of the long spirally-curved vegetative cone 

 of Utricularia vulgaris which he considers to be extra-axillary branches, while 

 normal shoots are formed in the axils of the leaves which stand in two rows on 

 the convex side of the shoot or by their side. It appears to me however certain 

 that these extra-axillary structures on the concave side of the mother-shoot are leaves 

 of peculiar form ^, since inflorescences are produced in their axils. 



The suppression of the bracts of the inflorescence, which is not uncommon, 

 cannot be placed in the same category as the cases just mentioned of extra-axillary 

 branching, where large leaves in the axils of which buds are also formed exist 

 near the extra-axillary lateral branches. Here, on the contrary, as for instance in 

 Cruciferse and the capitulum of many Compositae, the formation of leaves on the 

 branching axis of the inflorescence is itself entirely suppressed ; there are no leaves 

 in the axils of which the branches could stand. The branches are however produced 

 as if the leaves were actually there. With reference to the changes in the mode of 

 branching met with in passing from the vegetative to the floral region and to the 

 frequent transference of the bract on to the branch axillary to it, the remarks on 

 p. 598 may be consulted. 



Adventitious buds are rare in Dicotyledons, as they are in Phanerogams 

 generally. Those which are commonly formed with an exogenous origin in the 

 indentations of the margins of the leaves of Bryophyllum calycinum are well known, 

 and serve to propagate the plant. They sometimes occur (according to Peter- 

 hausen*) in Begonia coriacea in the form of small bulbs on the peltate surface of 



* See Guillard, Bull. Soc. Bot. de France, vol. IV, 1857, p. 239 (quoted by Duchartre, Elements 

 de Botanique, p. 408). 



^ Zur Morphologie der Utricularien, Monatsber. der konigl. Akab. der Wissench. Feb. 1869. 



3 This of course depends on what is considered leaf and what shoot ; this is not however a 

 matter of simple observation, but rather of conventional conceptions convenient for a special 

 purpose. 



* Beitrage zur Entwickelung der Brutknospen (Hameln 1869), where various examples are also 

 given of axillary buds of Dicotyledons which form deciduous gemmae; as in Polygonum viviparum, 



