Aril development in Celastraceae

To learn more about the evolution of secondarily intercalated seed envelopes, a series of developmental studies of arillate seeds in gymnosperms and angiosperms was undertaken. The goal was to test whether the second (outer) integument could be derived from an aril of gymnospermous ancestors. In our developmental studies of three species of Celastraceae, however, it turned out that the structure termed aril in this family does not originate from the funiculus or the hilum but from the exostomatic micropyle. As a consequence, the micropyle is not inside the aril but at the base of the fleshy structure which is thus better referred to as a caruncula. The fleshy part in seeds of Celastraceae differs thus markedly from those seed appendages usually referred to as an aril. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)