n] OF ANTHOCYANINS 27 



Alopecurus, Cynosurus, Dactylis). Pollen grains may also be coloured 

 with anthocyanin (Campanula). 



12. Many fruits form abundant anthocyanin. The pigment may 

 be temporary in some stages of development of capsules which eventually 

 become dry and dead (many of the Leguminosae, Hypericum, Sedum) 

 and schizocarps (Umbelliferae). The more obvious cases are the drupes 

 and berries, and of these, two types stand out, i.e. those in which the 

 pigment is limited to the epicarp (Prunus. Vitis), and those in which 

 it is present in both epicarp and mesocarp (Rubus, Ribes, Ligustrum, 

 V actinium, Atropa, Solanum, Sambucus, Viburnum, Lonicera). It may be 

 formed also in the tissues of 'false fruits' (Fragaria, Pyrus). From other 

 fruits (Cucurbita, Solanum, Lycopersicum, Citrus 1 ) it is entirely absent. 



13. Anthocyanin is sometimes developed in the cells of the testa 

 of seeds (Abrus, Phaseolus, Pisum). Further instances are the seeds 

 of Adenanthera, Erythrina, Lepeirosia (Potonie, 56), Trifolium pratense 

 (Preyer, 66) and many Podalyrieae (Lindinger, 76). More frequently 

 pigmentation in the seed-coat is due to impregnation of the cell-wall 

 by pigments which cannot be classified as anthocyanins, and of which 

 very little is known. 



14. Roots and underground stems often form anthocyanin in 

 considerable quantity. Three cases of this type of pigmentation may 

 be differentiated : 



(a) The pigment develops under ground apart from the influence 

 of any outside factors. Well-known examples for roots are Beta 

 vulgaris and Raphanus sativus, and for underground stems, Solanum 

 tuberosum; in the latter species the pigment may be confined to the 

 epidermal layers or may be present in the inner tissues (Salaman, 544). 

 To the above may be added other cases such as : 



Root-tips of species of Saxifragaceae and Crassulaceae (Irmisch, 27). 



Roots of Parietaria diffusa and Gesneria sp. (Zopf, 48). 



Roots of species of Pontederiaceae, Haemodoraceae and Cyperaceae 

 in the ground (Ascherson, 43). 



Roots of Wachendorfia in the ground (Hildebrand, 44). 



(6) The pigment develops in roots normally exposed. 



Aerial roots of Ficus indica (Mobius, 68). 



Floating roots of Pontederiaceae (Hildebrand, 44 ; Ascherson, 43). 



Aerial roots of Aroideae (van Tieghem, 33; Lierau, 51). 



Aerial roots of Orchidaceae (Leitgeb) 2 . 



1 Except in the red-fleshed variety, the so-called 'Blood Orange.' 



2 Leitgeb, H., 'Die Luftwurzeln der Orchideen,' Denkschr. Ak. Wiss., Wien, 1865, 

 xxrv, p. 179 (p. 204). 



