COHESION AND SUPPRESSION. 



255 



in Cucurbitacese. As a normal feature union of the 

 stamens is not at all infrequent : e. g. monadelphy in 

 Malvaceae and Leguminosas, diadelphy in Leguminosae, 

 polyadelphy in Hypericaceae, etc. 



In an otherwise normal andrcecium it sometimes 

 happens that two or more stamens become fused, as in 

 the 5-merous ones seen in the daffodil (Narcissus Pseudo- 

 narcissus), Lilium, etc., this condition being due to 

 fusion between two of the members, probably one from 

 each whorl. Celakovsky describes a very interesting 

 case of this phenomenon in the flowering-rush (Butomus 

 umbellatus) ; in the normal flower there are nine 

 stamens, six in the outer whorl, grouped in pairs 

 opposite the sepals, and three in the inner whorl oppo- 

 site the petals. This arrangement is obvious during 

 the first stage of development ; at a later stage, how- 

 ever, the inner whorl becomes intercalated in the outer. 

 In the abnormal flower it has happened, during the 

 later developmental stage, that two stamens of the inner 

 whorl have each become fused (for the whole or greater 

 part of the length of the filament, but not in the 

 anther-region) with a stamen of the outer whorl. 

 There would thus appear in this instance to be two 

 distinct steps in the blending of the two whorls into one. 

 Normal cases of the same kind occur in the Fumariaeese 

 and in Monsonia. 



The abnormally 4-merous flowers of Pentas, Primula, 

 Passiflora, etc., as also many normal cases of 4-mery 

 in Dicotyledons, may be attributed to fusion between 

 two members of the whorl of five, this fusion being so 

 profound as to leave no visible trace. 



Kirschleger observed in some virescent flowers of 

 the bleeding-heart (Dielytra spectabilis) two lateral 

 stamens of the outer whorl, and in the second whorl 

 two deeply-split filaments; the two branches of each 

 filament bore monothecal anthers. So that in this case 

 the monothecal stamens, instead of fusing, as in the 

 normal flower, with the stamens of the outer whorl, had 

 become united in pairs in the median plane. Hence a 



