POSIT I VK DEDOITBLEMENT. 



93 



In the section Prunese of the Rosaceas there is 

 normally but a single carpel; this is one of the most 

 extreme cases of reduction that we know of, for the 

 stamens are indefinite in number, and in other sections 

 of the order the carpels are also indefinite. In double 

 flowers of the cherry two carpels are almost invariably 

 present (PI. XXXVIII, fig. 1), and in this genus 

 (Prunvs) and Amygdalus so many as five are sometimes 

 found. 



In Spilanthes, one of the Composite, in which order 

 two carpels are the rule, there have been observed 

 indications of so many as five carpels. 



It was mentioned on a previous page that the flower 

 from which the modern Cruciferous bloom has been 

 directly derived may be regarded as one having two 

 whorls of stamens of four members each ; in that 

 ancestral flower there must also have been a whorl of 

 four carpels present, for in certain abnormal cases four 

 carpels, or indications of the missing two median ones, 

 are found. There is a permanent "sport" of the 

 marsh yellow-cress {Nasturtium palustre), placed by 

 some authors in a separate genus and termed Tetra- 

 porna barbaresefdia , which usually possesses four 

 carpels all equally developed. This must be regarded 

 as a reversion to the older condition. This plant, how- 

 ever, sometimes produces 2- and 3-carpellary fruits. 

 Nasturtium globvsum and A 7 , amjphibium also have been 

 found with 3-carpellary fruits. Holargidium normally 

 possesses four carpels. 



Cleome spinosa., of the Capparidacese, normally has 

 two carpels, like the Cruciferae. Abnormal flowers 

 (see p. 86, fig. 96 c) have four carpels, two extra smaller 

 ones being present in the median plane. This plant 

 obviously constitutes an interesting link between the 

 two orders. 



The sycamore {Acer PseudopJatanus) sometimes has 

 extra winged carpels present (PI. XXXVIII, fig. 3). 

 Turpin figures a heath with one or two extra whorls 

 of carpels present (fig. 103). 



