Floral structure in Licuala peltata (Arecaceae: Coryphoideae) with special reference to the architecture of the unusual labyrinthine nectary

Abstract

The structure and late development of the flowers of the South-East Asian bee-pollinated palm Licuala peltata are described with special focus on the architecture of the unusual labyrinthine nectaries. The nectaries are derived from septal nectaries by extensive convolution of the carpel flank surfaces below the ovary throughout the inner floral base, thus also encompassing the inner surface of the corolla–androecium tube. A comparison with septal nectaries elsewhere in Arecaceae and with labyrinthine nectaries in other monocots shows that labyrinthine nectaries situated below the ovary, as described here, are not known from any other palms, but are similar to those of a few Bromeliaceae and, less strongly convoluted, some Haemodoraceae and Xanthorrhoeaceae. In addition, the substantial participation of parts other than the gynoecium in the nectary architecture of Licuala appears unique at the level of monocots.