148 



PRINCIPLES OF PLANT-TERATOLOGY. 



Schauer and Moquin-Tandon observed in Aconitum 

 Stoerkeanum that all the petals (in the normal flower 

 very small, fiat structures) were provided with spur- 

 nectaries, this being evidently correlated with the 

 complete absence of a spur in the calyx. The normal 

 flower of the columbine- (Aquilegia) may be compared 

 with these cases of spur-pelory. 



Spurless Pelori/. — As the increase of spurred petals 

 constitutes one type of pelory, so the loss of the spurs 

 in the one or more petals which possess' them consti- 

 tutes a second type, just as we saw also occurred 

 with the calyx. 



This type has been seen in the violet (PI. XLII, 

 fig. 4), and in Linaria vulgaris. In orchids the 

 labellum sometimes becomes replaced by a petal in 

 all respects resembling the lateral petals. In Gymna- 

 clenia and the marsh-orchis {Orchis latifolia), however, 

 the labellum, although losing its spur, has become 

 different in form from the other petals. The peloric 

 condition in abnormal orchid-flowers, in which all the 

 petals are alike, producing a " regular " corolla, is, 

 of course, a reversion to the primitive condition which 

 actually occurs normally in the most ancestral group 

 of all, viz., the Apostasiese, in which Apostasia has a 

 perfectly regular perianth and Neuiviedia a sub-regular 

 one. 



In Delphinium the two posterior petals, which are 

 normally spurred, with their spurs inserted in that of 

 the posterior sepal, completely lose them in peloric 

 flowers. 



Miscellaneous PeJlory. — Leaving the spurred flowers, 

 we come to another type of zygomorphic flower in 

 which there is a greater amount of differentiation 

 among the petals, as in the group Papilionacese of the 

 Leguminosa3, where three kinds occur in each flower, 

 viz., the " standard," " wings," and " keel." In such a 

 flower pelory or actinomorphy may arise in two 

 ways: (1) the " wing "- and " keel "-petals become 

 developed exactly like the " standard," giving rise to 



