Functional interpretations of the morphology and anatomy of septal nectaries

This review synthesizes personal observations on the septal nectaries (hereafter “SNs”) of 40 species, 32 genera, and 17 families (families sensu Airy Shaw 1973) with the extensive old literature (much of it pre-1900) and especially with Daumann’s (1970) landmark study of the SNs of 202 species, 107 genera, and 21 families. Daumann examined a total of 427 species, 197 genera, and 34 families of monocotyledons, whereas my sample is, respectively, 112,84, and 35. “Septal nectary” is defined as follows: a nectariferous, that is sugar- or nectarsecreting, cavity resulting from lack of intercarpellary postgenital fusion and lying in a septal radius (“septum” here is too restrictive because a few taxa with SNs have parietal placentation, eg, Burmanniaceae). The SN may be strictly external (“outer SN”), internal with a non-nectariferous opening to the exterior (“inner SN”), or a combination (“confluent SN”, eg, Daumann’s fig. 7-9).