Farinose exudates

See D. M. Smith, 1980, for a study of flavonoid profiles of the varieties.) The overall flavonoid profile of P. triangularis is fully in accord with the uifique status of the species. A detailed discussion of the chemistry of this system, which is beyond the scope of the present treatment, can be found in a paper by Wollenweber and Dietz (1980). An example of the complexity of flavonoid biosynthesis in this species can be found in a description of biflavonoids present in the farinose exudate (linuma et al., 1994). 

Asai, F. et al., Five complex flavonoids in the farinose exudate of Pityrogramma calomelanos. Phytochemistry, 31, 2487, 1992. 

Wollenweber, E., Armbruster, S., and Roitman, J.N., A herbacetin methyl ether from the farinose exudate of a Pentagramma triangularis hybrid, Phytochemistry, 37, 455, 1994. 

The farinose exudate of the frond of the fern Pityrogramma calomelanos (Adiantaceae) has been the source of complex flavonoids characterized by a novel Ce-Cs-Ce-Cs-Ce skeleton (Table 15.7). This group includes four flavanones, calomelanols G (238), H (239), I (240), and J (241) (Figure 15.10). In these compounds, a molecule of p-coumaric or cinnamic acid appears to be fused with the A-ring of the flavanone. Biosynthetic pathways for these complex flavanones and related flavones, chalcones, and dihydrochalcones in P. calomelanos and other Pityrogramma species have been proposed by the authors. 

Farinose Exudates of the Polypodlaceae and Prlmulaceae. Members of the Polypodlaceae produce a yellow or white powdery deposit on the lower surface of their fronds. These deposits are usually referred to as farinose exudates. Farina from species of Pltyrogramma, Chellanthes, Adlantum, and Notholaena have been carefully studied. The farinose coating of these plants Is formed by the terminal cell of small hairs usually found on the lower surface of the frond. 

Many primroses (Primula) also produce a farinose exudate on their stems and leaves. Eighteen species have been investigated... 

Commonly, flavones are present in vacuoles of cells as O- and/or C-glycosides, but some compounds, especially simple and polymethylated flavones, occur in heartwood of Prunus species farinose exudates of Primula spp. and ferns ... 

Flavone aglycones more than 400 kinds Prunus (Rosaceae) (heartwoods), Alnus, Betula, Ostrya (Betulaceae) (bud wax). Primula (Primulaceae) (farinose exudates), Pityrogramma, Cheilanthes, Notholaena (pteridophytes) (farinose exudates), etc. 

Wollenweber E (1978) The distribution and chemical constituents of the farinose exudates in gymnogrammoid ferns. Am Fern J 68 13-28... 

The Occurrence of Flavanones in the Farinose Exudate of the Fern Onychium sili-culosum. Phytochem. 21, 1462 (1982). 

WoLLENWEBER, E. The Distribution and Chemical Constituents of the Farinose Exudates in Gymnogrammoid Ferns. Amer. Fern J. 68, 13 (1978). 

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