146
WILLIAM MACNAE
I n the Rhizophoraceae, endosperm is unimportant. The radicle
develops rapidly and grows out from the apex of the fruit through the
tip of a cotyledonary body. This radicle continues to grow, in shape
like a cigar, until it reaches a considerable length, up to 40 cm in
R. mucronata (Fig. 42, 2). I n species of Rhizophora and of Ceriops the
cotyledonary body emerges from the fruit around the radicle, and its
appearance indicates that the seedling is almost ready to drop. This
body does not emerge in species of Bruguiera (Fig. 42, 1 and 3). Its
function is to absorb nutrients from the fruit. The seedling alone is
dropped in species of Rhizophora and of Ceriops but in Bruguiera the
PIG. 42. Seedlings of viviparous species of mangrove. ( 1 ) Bruguiera yymnorhiza; ( 2 )
Rhizophora mucronata; (3) Bruguiera parvi$ora with plumule emorging through
calyx; (4) Avicennia marina (a) newly germinated, (b) plumule elongating; ( 5 )
Aegiceras corniculatum (a) bunch of fruits, (b) young fruit and (c) germinating fruit.