610 BOWMAN— ECOLOGY AND 



furrows are lateral or subintrorse and the pollen sacs are areolate- 

 multilocellate. 



The ovary is half inferior, bi-locular and at the vertex produced 

 into a cone. Style subulate, sometimes rather short, at the apex 

 stigmatose and bidentate. There are two ovules in each cell, placed 

 in a collarterally descending position, the micropyle being extrorsely 

 superior. • 



The fruit is berry-like, coriaceous and indehiscent, surrounded 

 below the middle by the reflexed persistent calyx. Only one ovule 

 matures into a seed. The embryo is exalbuminous with fused coty- 

 ledons. The radicle or hypocotyl perforates the apex of the seed 

 and germinates within the fruit ; at length pushing out through the 

 pericarp, greatly elongates while still on the tree. An absciss layer 

 is finally formed at the junction of the cotyledonary sheath and the 

 shoulder of the hypocotyl, and the seedling drops from the parent 

 tree into the mud or water. 



The Roots. 



The roots of the mangrove, even as mentioned by the ancient 

 Greeks, are a peculiar feature of the genus, being, as Theophrastus 

 says, like " polypi." The primary root put out by the radicular end 

 of the hypocotyl soon stops growth and the root function is given 

 over entirely to secondary roots. The cause of cessation of growth 

 by the primary roots has been suggested by Warming,**^ Johow,''^ 

 Schimper,''^ and others, as due to the bites of crabs, snails or other 

 mechanical injury. At any rate the primary root does not long 

 persist and the plant is soon anchored by a rich mass of secondary 

 roots. The structure of the roots is very interesting. There are 

 really two types of roots, those prop-roots arising from the base of 

 the tree and bending out to form the curved stilts, and the adven- 

 titious roots dropped from the lower branches are one kind and are 

 known as the aerial or aerating or pneumatophore roots, while those 



65 Warming, Eug., " Rhizophora Mangle, Tropisclie Fragmente," Engler's 

 Jahrb. fiir Syst., Bd. 4, p. 520. 



6*^ Johow, Fr., " Veget'ationsbilder aus West Indien und Venezuela, Die 

 Mangrove Siimpfe, Kosmos," Bd. I., pp. 415-426, 1884. 



^" Schimper, A. F. W., " Indo-Malayische Strandflora," Bot. Mithcilnngen 

 aus dcs Tropen, Heft 3, 1891. 



