PHYSIOLOGY OF THE RED MANGROVE. 609 



King*^^ has this point clear in his Malayan Flora, where he says 

 R. mucronata — R. mangle Roxb. (not Linn.) and also R. macrorhiza 

 Griff, while R. conjugata Lam. — R. candclaria of De Candolle. 



R. mangle Linn, is a purely American species, but has been found 

 by Guppy associated with the Oriental species in some of the islands 



in the South Pacific. 



« 



Morphology and Histology. 



The gross morpholog>^ of Rhizophora mangle is synopsized in 

 any flora or manual of the species of the tropics in which the plants 

 are found. But it is well perhaps to set down the chief features of 

 their structure here. (See Plate IX.) The red mangrove may be 

 a large tree 60 to 80 feet tall, or smaller shrub 6 to 18 feet tall. 

 This varies with the region and has given rise to the two types based 

 on size, i. e., the " Mangle chico " and " Mangle grande." The 

 primary root soon dies out, secondary roots are put out by the 

 seedling. Later adventitious prop-roots are put out from the base 

 of the stem and from a mass of arched stilts about the tree. The 

 branching is opposite and from the lower branches aerating roots 

 are let down to the substratum, these also assist the prop-roots 

 in anchoring the tree. The twigs are stiff, cicatrized and thick, 

 and the wood throughout the tree is very hard and dense. 



The leaves are opposite, clustered on the ends of the twigs and 

 furnished with large inter-petiolate and caducous stipules. They 

 are decussate, petiolate, elliptic, entire, glabrous thick and coriaceous. 



The flowers are yellowish or whitish, coriaceous and axillary ; col- 

 lected into bi- triparous. rarely simple and more generally ramified 

 cymes at the summit of a common peduncle. These flowers are 

 usually pedicellate, articulate and have mostly two connate bracteoles 

 forming a sort of involucre. The flower is regular with a concave 

 obconical receptacle. The sepals are four in number inserted on the 

 margin of the receptacle, coriaceous and valvate ; and the petals are 

 also four, alternate with the sepals and valvate. The stamens are 

 mostly eight, with four larger ones oppositipetalous, and have many 

 short filaments or none at all. The anthers are unique. The anther 



'^^ King, Geo., " Materials for a Flora of the Mala3^an Peninsula," Vol. 3, 

 p. 313, Calcutta, 1902. 



