Inflorescence and Flower Development of Globba barthei(Zingiberaceae)

Inflorescence of Globba barthei is a thyrse.Primary bracts are initiated in a spiral phyllotactic pattern on the inflorescence apex.Cincinnus primordia are initiated in the axils of primary bracts.These promordia develop secondary bracts and floral primordia.The floral primordium continues to enlarge and produce a ring primordium.Sepals are initiated sequentially from the rounded corner of the primordium.The ring primordium separates three common primordium surrounding a central cavity.The adaxial common primordium is the first to separate.This primordium divides transversely and produces petal and fertile stamen.The remaining two common primordium transversely separate and produce respectively a petal and a petaloid.As the flower developing,the cavity of the floral cup becomes triangular.The angles of this triangle are the sites of outer androecial primordium.The abaxial androecia forms slightly earlier than the two adaxial ones,and then this primordium ceases growth soon.The two posterior primordia continue growth to produce the lateral petaloid staminodes.During this stage,gynoecia initiate from the floral cup and continue to fuse and develop into style and stigma.In addition,Initiation of the bulbil primordium is observed at base of inflorescence axis during the early floral development.The bulbil primordium initiates in the axil of primary bract.The evolutionary significance of six androecia is discussed.