The flowers produce only a tiny amount of nectar. The nectar is rich in hexose sugars. It contains a relatively small concentration of amino acids among which there is an especially high amount of the glutamic acid, tyrosine and proline, the last of which can be tasted by, and is favoured by, many insects. It also contains (four) alkaloids, in relatively high concentration compared to the flowers of other species, among them the toxins harmalol and harmine. The proportions and concentrations of the alkaloids in the nectar are different than in the other organs of the plant, indicating an adaptive reason for their presence.
