Vol. XVI. No. 6— Botanical Gazette — June, 1891. 



Abnormal phyllotactie conditions as shown by the leaves 



or flowers of certain plants. 



AUG. F. FOERSTE. 



(with PLATE XIV.) 



Sanguinaria Canadensis. — Baillon interpreted the flowers 

 of the blood-root so .as to make the petals form two decus- 

 sating dimerous whorls, which by dedoublement have become 

 whorls of four petals each. The petals of the inner whorl 

 should therefore be directly superposed to those of the outer 

 whorl, and the two sepals should occupy a position interme- 

 diate between two petals of the outer whorl in each case. 

 Eichler, in his important work "Bliithendiagramme," copies 

 this view. Unfortunately this interpretation is incorrect, as 

 may be seen at any locality where the blood-root is at all 

 common. For the purpose of the following notes many hun- 

 dreds of flowers were examined, and the accompanying dia- 

 grams illustrate all the cases found. 



It is not a rare occurrence in some, perhaps isolated, local- 

 ities to find a single scale about half way up the flower 

 peduncle, subtending a second flower. In this case the sepals 

 of the subtended flower seem to occupy a position transverse 

 to that of the scale. The outer set of four petals is inter- 

 preted as consisting of two dimerous whorls, the lower pair 

 of petals decussating with the sepals, and the other pair of petals 

 taking a position directly above the sepals. The inner set of 

 lour petals alternates with the outer set taken as a whole, and 

 may be interpreted either as a dimerous whorl decussating 

 With the second pair of petals, and numbering four in con i- 

 quence of dedoublement, or as a whorl of four petals, showing 

 the usual arrangement of whorls consisting > four members 

 preceding or following dimerous whorls. The latter inter- 

 pretation is shown to be the correct one by such cases as are 

 represented by fig. 3, in which the inner whorl of petals is 

 reduced to three, but the odd petal never occupies a median 

 position above one of the outer petals, as it should if it rep- 

 resented the undivided petal of a dimerous whorl. The 

 pistil consists of two leaves, which typically decussate with 



