Abstract
1. The flower types found in Cosmos bipinnatus CAV. can be classified into the following four main groups: single-fiowered types, double-fiower.ed types, malform-flowered types and malformdouble mixed types (see Fig. 1). 2. The single-flowerd type, when inbred, does not segregate any of the other types. 3. The non-petalous type (Np type), when inbred, always produces the non-petalous only, while the other malform-flowered or the doubleflowered, when inbred or crossed to one another, segregate into all types, including single, double and malform-flowered types. 4. The crossing of the non-petalous to the normal single-flowered produces every kind of flower types in F2, which means that the non-petalous involves the factors for doubleness or malformiity. Many slightly-doubled plants appear in F2, which segregate a few highly-doubled plarts in the following generation.
