Morphology and Anatomy of the Inflorescence Axis and Flowers in Arenga Porphyrocarpa (Palmae)

E.B. Hidajat,

Data & Software Engineering Research Group
STEI-ITB, Jl. Ganeca No.10, Bandung 40132, Indonesia

In Arenga Porphyrocarpa the vegetative axis is terminalised by the onset of the hapaxanthic flowering axis. This is accompanied by a reduction of leaf size. The part of the axis beyond the last node transforms into a female inflorescence which consists of a system of rachillae on which the individual flowers are attached. Male inflorescences develop afterwards on the remaining nodes but may also develop from the most distal node later on. Additional female inflorescence may develop at lower nodes.

Monopodial branching is not confined to  the reproductive axis only but occurs also in the branching system of  the inflorescence. Although flowers occur solitary at the female rachilla or in pairs generally at the male rachilla, ontogenetic examination shows that the basic pattern is a flower cluster of three. At the female rachilla only the central latest developing flower matures while at the male rachilla only the two marginal flowers develop. Presumably the type of branching in a flower cluster follows a sympodial pattern.

In the female flower, the stipitate gynoecium contains two ovules which not may be of the same size. The stigmatic region leads to a cleft like stylar canal. Three staminodia occur at the female flower. The male flower carries 19-20 stamens each one consisting of a short filament and a long latrorse anther.

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