80 



PRINCIPLES OF PLANT-TERATOLOGY. 



illegitimate position. It is not at all infrequent in Iris 

 for this inner whorl, in the form of stamens, staminodes, 

 or petals, to reappear in abnormal flowers ; in such 

 cases it may be complete or incomplete. Heinricher, 

 dealing with Iris pallida, has written excellent treatises 

 on ^ this subject. It is an interesting fact that in 

 Tritonia bracteata the three stamens of the inner whorl 

 are present in the form of staminodes. 



No one can doubt that the flower of the lady's mantle 

 (Alchemilla) has been reduced from a more richly- 

 furnished type of flower such as occurs in most other 

 members of the Rosacea?. It has only four stamens, 

 alternating with the four sepals. Hence we may regard 

 it as a case of reversion when a flower, such as that 

 mentioned by Eichler, produces an inner episepalous 

 whorl of from one to three members. 



In some of the Caryophyllaceas three or four whorls 

 of stamens, in place of the normal two, are sometimes 

 found, probably also a case of reversion. 



In the flowering rush (Butomus umbellatus) the six 

 stamens are arranged in pairs opposite the sepals. 

 Buchenau found in 10- to 11-androus flowers that the 

 one or two extra stamens were inserted below the 

 whorl of six, and exactly opposite the sepals. To ex- 

 plain their presence Eichler supposed that the original 

 three rudiments split into three instead of two, and the 

 middle of each three became pushed outwards ; for if 

 the extra stamens constituted a separate outer whorl, 

 as Buchenau supposed, being opposite to the pairs of 

 stamens of the normal whorl, they would violate the 

 law of alternation. Celakovsky, as usual, saves the 

 situation by finding that the presence of these extra 

 stamens is a partial reversion to the ancestral condition 

 in which two extra outer whorls were present ; that 

 these stamens belong to the outermost episepalous 

 whorl, and that the epipetalous whorl is suppressed 

 (PI. XXXVII, fig. 4, and fig. 93 in text). For in the 

 frogbit (Hydrocharis) these two outer whorls are actually 

 present in the normal flower as staminodes. Thus, once 



