Nectar secretion in the flowers of comfrey (Symphytum officinale L.) and nectar chemistry

Abstract

Nectar secretion and nectar chemistry in the flowers of comfrey (<i>Symphytum officinale</i> L.) were examined in the four stages of anthesis: large buds, before pollen exposure: II - freshy opened flowers with the beginning of anther dehiscence: III- completely opened flowers in the maximum of pollen exposure: lV- flowers at the final stage of anthesis, without pollen in the anthers. Individual flower stays fresh 2,5-3 days, on average. Disc-shaped nectaries of S.officinale are located at the base of the four-lobbed ovary. Nectar is released through the modified stomata. Start of nectar secretion was noted at the bud stage. Nectar volume, mass of nectar and sugars differed in the examined stages of anthesis and the biggest values were noted at the final stages. Dominant sugar in nectar was sucrose with smaller amounts of fructose and glucose. The presence of amino acids was also recorded.