168 ALTERATION OF POSITION. 



escence is made up of collections of scales or bracts 

 with no trace of floral structure. Fig. 79 shows this 

 in a species of WiUde7iaviaf and a very good example is 

 figured in a bamboo, Pseudostachyum polymorphumy by 

 General Munro.^ 



" Rose willows" (fig. 80) owe their peculiar appear- 

 ance to a similar cause, the scales of the catkin being here 

 replaced by closely crowded leaves. These aggregations 

 of scales or leaves are not confined to the inflorescence, 

 but may be found in other parts of the plant, and may 

 be frequently met with in the willow, birch, oak, &c., 

 generally as the result of insect puncture. On the 

 other hand, the production of leaves or leaf-buds in 

 place of flowers is, as is well kno^vn, generally the 

 consequence of an excess of nutrition, and of the con- 

 tinuance rather than of the arrest of vegetative develop- 

 ment.^ It has even been asserted that a flower-bud 

 may be transformed into a leaf-bud by removing the 

 pistil at a very early stage of development, but this 

 statement requires fiirther confirmation.^ 



Viviparous plants. The spikelets of certain grasses are 

 frequently found with some of their constituent parts 

 completely replaced by leaves, like those of the stem, 

 while the true flowers are usually entirely absent. A 

 shoot, in fact, is formed in place of a series of flowers. 

 In these cases it generally happens that the outermost 

 glumes are changed, sometimes, however, even the 

 outer and inner paleee are wholly unchanged, while 

 there is no trace of squamulse or of stamens and pistils 

 within them, but in their place is a small shoot with 

 miniature leaves arranged in the ordinary manner. 



' Trans. Linn. Soc.,' xxvi, p. 142, tab. iv, B. 



^ " Si arbusculam, quae in oWh antea posita, quotannis floruit et 

 finictus protulit, deinde deponamus in uberiori terra calidi caldarii, 

 proferet ilia per plures annos multos ac frondosos ramos, sine ullo 

 n-uctu. Id quod argument est, folia inde crescere, unde prius enati 

 sunt flores; quemadmodum vicissim, quod in folia nunc succrescit, id, 

 natura ita moderante, in flores mutatur, si cadom ai-bor itcrum in oM 

 Beritur." Linnaius, ' Prolepsis,* iii. 



! ' Bev. Hortic,' May, 1868, ' Gardeners' Chronicle,' 1868, pp. 572, 737. 



