Aspects of Floral Morphology and Development in the Seagrass Syringodium filiforme (Cymodoceaceae)

Abstract

Inflorescences in Syringodium filiforme are initially racemose and subsequently extensively cymose, with terminal units referred to as "flowers." The species is dioecious. Each unit is normally enclosed by a pair of bracts which may subtend renewal shoots. The male flower consists of four pairs of microsporangia which arise by equal subdivision of two lobes of the floral apex. Each pair of microsporangia is associated with a late-developing protuberance, which collectively fuse to form a "perianth ridge," soon obscured by the enlarging microsporangia. The female flower is naked and consists of two carpels which arise separately on the floral apex. The carpel is initially peltate but matures as a closed structure with a single pendulous ovule and two styles. The homology of these structures with the parts of a normal flower is discussed and compared with several related genera for which similar information is available.