186 TRANSACTIONS OF THE [Sess. lxxvii. 



Embryo of Laguncularia racemosa, Gaertn. 

 By Professor Bayley Balfour, F.R.S. (Plate VIb.) 



Laguncularia racemosa, Gaertn., is a combretaceous 

 bush of the Western Mangrove spread over the shores of 

 West Tropical Africa and of West and East Tropical 

 America. Its life-history and construction are less known 

 than those of most of the other mangrove plants. I have 

 found no published record of its germination or of the form 

 of the seedling — a feature to which the peculiar environ- 

 ment of mangroves gives particular interest. 



I have had occasion to look at the fruit and embryo of 

 the species in an excellent herbarium specimen from 

 Florida, and whilst such material does not give evidence 

 that enables one to depict with accuracy either embryogeny 

 or germination, it has supplied in this case data sufficient 

 to supplement published descriptions of the construction of 

 the embryo. 



The sessile fruits of Laguncularia are produced in 

 profusion on the long branches of the inflorescence-axis. 

 They are not pendent and are easily detached from the 

 axis — characters all of which do not suggest vivipary. 



The dry, one-seeded, one-celled fruit is derived from an 

 inferior ovary and has a spongy, leathery pericarp. 

 Crowning the fruit is a turbinate, leathery calyx, within 

 which lies the hardened flower-disk with the style in the 

 centre, and this intercalycine mass forms a stopper which 

 ultimately separates by a circumscissile slit. The fruit is 

 therefore technically a dehiscent one, but the dehiscence is 

 certainly not active. The club-shaped or elongated pyrif orm 

 seed has a thin resinous seed-coat and hangs from the roof 

 of the fruit cavity with the micropyle upwards. 



The embryo is green within the seed, as frequently 

 happens amongst the Combretaceae. It fills up the whole 

 seed-cavity. There is no food store in the seed outside the 

 embryo. As it lies in the seed the embryo is a somewhat 

 cylindric, fat, and fleshy body about 1*5 cm. long, 2'5 mm. 

 broad, rounded at the basal end, and running out to a 

 narrower apical end. It consists of a central axis which is 

 enwrapped by two cotyledonary folds. 



In technical language the embryo has convolute coty- 



