Seed structure in cannaceae: Taxonomic and ecological implications

Abstract

The ovules and seeds of Canna show some striking differences to those in other zingiberalean families. The pachychalazal development of the ovule results in a seed of which only a small part of the testa is of tegumentary origin. A silicified endotesta, characteristic of the order, is lacking. The mechanical layer of the seed is formed by a continuous exotesta of Malpighian cells. The intact seed coat is impermeable. The seed is able to absorb water after the raising of a preformed imbibition lid on the raphe. During imbibition the extotesta loses its hardness, allowing the embryo to emerge. The special structural features of the seed are discussed in relation to records on the extreme longevity of Canna seeds. © 1988 Annals of Botany Company.