Floral Ontogeny and Morphology inGillenia(“Spiraeoideae”) and Subfamily Maloideae C. Weber (Rosaceae)

Abstract

A comparison of floral development in Gillenia (Rosaceae subfamily “Spiraeoideae”) with that in seven genera in subfamily Maloideae was undertaken to ascertain similarities between Maloideae and Gillenia floral development, as well as to ascertain the developmental basis for variation in mature Maloideae floral morphology. The analysis also sought information regarding the initiation and development of the syncarpous hypanthial ovary that is encountered in the majority of Maloideae taxa. While most taxa in this study initiated 20 stamens in three pentamerous whorls, flowers of Chaenomeles and Mespilus each initiated more than three whorls of stamens. Development of the gynoecium in all taxa was preceded by a ring primordium in the Maloideae and a flat‐topped primordium in Gillenia. Individual gynoecial units formed on these primordia and in all taxa except Cotoneaster remained connate throughout development. Except in Gillenia, intercalary growth beneath the common insertion point of the gynoecial primord...