A CAROTENOIDS IN PLANTS 67 



presence of carotenoids may be assumed in the materials examined. Definite 

 conclusions regarding the nature of the individual pigments can only be drawn 

 after repeated chromatographic analysis. For this reason no attempt has been 

 made to identify the pigments reported in these older investigations. 



A. CAROTENOIDS IN PLANTS*' ** 



I. PHANEROGAMS 



a) Carotenoids in unexposed parts of plants 

 TABLE 16 (References see p. 99-107) 



CAROTENOIDS IN ROOTS 



Beta vulgaris''-. Escobedia scabrifolia^: Azafrin. 



Brassica campestris^. Ipomoea Batatas': a-Carotene, /5-caro- 

 Brassica Rapa^. tene. 



Cetastrus scandens^: ^-Carotene {}). Jaundiced potatoes^: Taraxanthin or 

 Daucus Carota^: a-Carotene, /3-carotene, violaxanthin, xanthophyll, a-caro- 



y-carotene, a hydrocarbon of un- tene(?). 



known constitution (absorption maxi- Sweet potatoes^: Carotene. 



ma in CSgi 482, 453 m/^), a second Pastinaca sativa^'^. 



hydrocarbon of unknown constitution 



(absorption maxima in CSg: 499, 



469 mix), xanthophyll. 



b) Carotenoids in exposed parts of plants 

 Green parts of plants 



It has long been known that besides chlorophyll, all green parts of plants 

 contain carotenoids^. These are mainly /9-carotene, xanthophyll and, according 

 to the most recent investigations^, xanthophyll epoxide. Small amounts of 

 a-carotene are also usually present. The carotenoids are found together with 

 chlorophyll in the chromatophores and are present in either an amorphous or 

 crystalline state. 



The ratio of carotene to xanthophyll in green leaves has been investigated 

 by WiLLSTATTER and Stoll^ and by Karrer and co-workers*. Whereas the 

 former found a ratio of 1.7, the latter obtained values tending to unity. In all 

 the older investigations the fact that the so-called xanthophyll fraction consists 



* The following abreviations are employed in the tables in this chapter : 

 ■*" = isolated in the crystalline state ; 

 ■*"■*" = definitely present; 

 "^+"'" = probably present. 

 ** The literature references for the tables in this chapter will be found at the end of 

 the general part (p. 99-107). 



References p. 108. 



