COHESION AND SUPPRESSION. 



243 



whose older members, as Papaver, are clearly closely 

 allied to, and derived recently from, the Polycarpicae (as 

 Celakovsky points out), and have their parts in threes. 



The corolla of Portulacacese is also 2 + 3-merous, 

 its perianth having three whorls in all, like that of the 

 Papaveraceae and Cruciferge. 



In the lily-flower there were five stamens which did 

 not alternate exactly with the perianth-leaves ; the 

 pentamery here was probably clue to fusion of two 

 stamens ; but this was not particulary noted. Of the 

 normal three carpels two were partly fused together. 

 The formula of this flower was therefore K2| C2^ A 

 2 + 3 (or 3 + 2) G2 ( — 3). A second terminal flower 

 had just the same structure. A third had a perianth of 

 four leaves, of which one was completely external and 

 one completely internal, and two (lateral) ones which 

 were half external and half internal, representing a 

 fusion of two sepals each with a petal ; there were 

 five stamens and three carpels. The floral formula in 

 this case would be K1H ^Hi A3 + 2 G ?>. A fourth 

 flower had the same 5-merous perianth, but andrcecium 

 and gynceceum were normal. Pentamerous flowers of 

 Pancratium and Narcissus Pseudo-narcissus may also 

 be mentioned.* 



Tetramerous flowers replacing the normal 5-merous 

 ones are not infrequent in Dicotyledons, as in examples 

 observed in Pentas, Primula, and Passiflora ; in this last 

 flower there were only two carpels. 



Trimerous flowers were also exhibited by a Pentas. 

 Fuchsia offers another case. Magnin describes a plant 

 of herb-Paris (Paris quadrifolia) which was 3-merous 

 throughout, thus showing a reduction by one member 

 in all its whorls. 



Dimerous flowers, which at the same time naturally 

 become pre-eminently peloric, are common in orchids ; 



* A 5-merous flower of Txdi'pa persica was recently seen in which two 

 perianth -leaves were completely external, two completely internal, while 

 one was half in- and half outside. There were five stamens alternating Avith 

 the perianth-leaves, and two carpels. 



