Variations in floral development in Peperomia (Piperaceae) and their taxonomic implications

Abstract

The floral development of two species of Peperomia, Peperomia reflexa A. Dietr. (P. tetraphylla (G. Forst.) Hook. et Arn.) and P. serpens C. DC., is described. The initiation order is in an acropetal succession and resembles that in P. metallica L. Lind. et Rod., P. pellucida (L.) Kunth and Il rubella Hook., although many more bracts are produced in these two species than in P. metallica. The arrangement of bracts and floral primordia is orthostichous in P. reflexa: but parastichous in P. serpens. The floral apices in P. reflexa are transversely ellipsoidal protuberances at first, then become saddle-shaped when they begin to produce simultaneously staminal primordia. They are similar to those of P. metallica, P. pellucida and P. rubella. However, their initiation of floral primordia is much delayed compared to the size of the bracts. The triangular ol transversely cuneate ridges then become L-shaped in P. serpens; this shape is related to the parastichous phyllotaxy of the bracts. So, the staminal primordia are successively initiated and develop at different rates. Therefore, they are not always the same size. The staminal primordia are initiated above the level of the floral apex in P. reflexa and P. serpens but below it in P. metallica, P. pellucida and P. rubella. The abaxial position of the carpel primordium on the apex and the closure of the ovary in 19 reflexa and 19 serpens are also similar to those in P. metallica, P. pellucida and P. rubella. The shape of the upper part of the ovary, stigmas and indumentum vary between the species. In P. reflexa, the upper part of the ovary becomes ovoid and acclivous, or leaning acropetally, to the axis of inflorescence. In P. serpens, it becomes helmet-shaped. The flowers of P. serpens are surrounded by the outgrowth of the axis of the inflorescence. The ontogenetical features of ovaries in Peperomia indicate that the fruit characters are useful in the taxonomy of the genus. (C) 1999 The Linnean Society of London.