152 CHAEACTEEISTICS OF THE MANGROVE-TREE. 



slightly to the soil ; the advancing and retreating waves move the little plant 

 up and down until it works a hole in the sand, and having thus established 

 itself more firmly — steadied itself, as it were — it now stands upright." 



The mangrove has a low, branching stem, and is thus pretty much all 

 head; you cannot see anything as you approach but a compact mass of 

 brightly green, thick, shining leaves, trailing to the ground. A nearer 

 view discloses another very curious feature. From the main trunk, near 

 the ground, extend out on all sides, and at varying height, some branches 

 which do not go upward and bear leaves, but turn downward, enter the 

 ground, and become roots. There are dozens of these stays surrounding 

 every stem, and holding it, like so many cables, against the fury of the 

 storms which sometimes hurl both wind and waves against the groves. 

 But this is not all. Every low branch produces a considerable number of 

 thick, leafless, straight twigs, which elongate straight downward through 

 air and water until they penetrate the soil and become rooted. The man- 

 grove is not only braced upon a score of roots, therefore, but anchored 

 from every one of its lower and larger arms. A perfect tangle and net- 

 work of these roots and rooted stems thus surrounds each tree and every 

 islet with an abatis often several rods in width. 



Such a net-work speedily verifies its likeness to a basket by catching 

 outside matter. Along the solid edges of the key itself, and everywhere 

 in the neighborhood, are living oysters which annually send forth a cloud 

 of young to seek new quarters. The mangrove stems afford capital rest- 

 ing-places, and, therefore, speedily become incased in infant oysters which 

 increase in size and number very rapidly. This suspended kind is known 

 as the " mangrove oyster ;" but I do not see that they are anything differ- 

 ent from the progeny of the 'coon bars. Barnacles, too, in vast numbers, 

 mussels, bryozoa, and forty forms of minute water animals cling to these 

 half-submerged branches or flourish under their shelter, where the hard 

 sand and bare angles of oyster-rock are slowly buried beneath a coating 

 of mud and decayed vegetation, which the basket-work of mangrove roots 

 and salt-grass has caught and confined, so that henceforth it is in small 

 danger of washing away. 



An especially noteworthy member of such a colony is a marine worm 

 of small size, which forms about itself a tubular, twisted case of lime very 

 like that of the Serpula. Along certain portions of the coast, south of 

 Tampa Bay, these worms are extremely numerous; and they build up 

 their cases so closely together that they join one another, and so cover 

 the foundation on which they grow with vertical calcareous tubes some- 

 what larger than a darning-needle. 



