LEAVES. 437 



of flowers, becomes a raceme from the elongation of 

 the pedicels. In Umbelliferce a similar change occurs, 

 by virtue of which sometimes the umbels themselves, 

 and at other times the florets, are raised on unusually 

 long stalks, as in Angelica llazoulzii, Carum Carul, 

 Thysselinum palustre} In Gompositce, when affected 

 by an analogous change, the capitulum assumes the 

 appearance of a simple umbel, as in Hypochwris radicata, 

 Senecio vulgaris , and other plants. 



In some of the double-flowered apples which have 

 been previously alluded to, the flower-stalk is inordi- 

 nately long when compared with the adjacent ones. 

 Possibly in some of these cases the absence of the 

 usual swelling of the upper part of the peduncle may 

 be connected with its increased length. One of the 

 most striking instances of lengthened flower-stalk 

 occurred in an apple flower, wherein there was no 

 swelling beneath the calyx, while the latter was repre- 

 sented by five perfect stalked leaves. 



Elongation of the leaves. In the case of water plants 

 this change keeps pace with the corresponding growth 

 of the stem, e. g. Banunculus Jluitans, and in terrestrial 

 plants there are varieties termed longifohar, from the 

 unusual length of the leaves. A similar lengthening 

 occurs in the involucral leaves of Umbelliferce and Com- 

 positce^ changing very materially the general aspect of 

 the inflorescence. Occasionally, also, the leaf-lobes of 

 parsley {Apmm Petroselinum) and other crested-leaved 

 plants may be observed to lose their ordinary wavy 

 form, and to be lengthened into flat riband-like seg- 

 ments, as shown in fig. 207. 



The only further illustrations that it is requisite to 

 give of such changes in this place are those occurring 

 in lobed or compounded leaves, which, from a lengthen- 

 ing of the midrib or central stalk, convert a digitate 

 or palmate leaf into a pinnate one. In these instances 



' See Cramer, ' Bildnngsabweich,' pp. 62 79, and Fleischer, ' Missbild. 

 der Cultxirpflanzen.' 



