The ascidiform early development of free carpels, a S.E.M.-investigation

Carpels develop centripetally as oblique slightly ascidiform structures provided with a seat-like support. The terminal mouth of the ascidiform primordium becomes the lateral cleft of the carpel. Solitary terminal carpels develop as lateral structures. The sections Tasmannia and Drimys of the genus Drimys differ by the varying degree of ascidiform development. Austrobaileya is like Drimys. The structure of the carpel margins with submarginal placentation may have evolved from a slit like that in Winteraceae. Allometric development of an oblique ascidiform structure may have formed a large basal ovary, and may thus have moved the stigmatic part apically. A possible cupular origin of carpels is discussed.