975 



QL\)t €rea£ttrg nf 23fltang. 



[ehod 



niacece, but still more to Lytliracece. It 

 consists of tropical trees or shrubs, with 

 opposite entire leaves, and axillary flowers, 

 either solitary or in cymes or clusters. 

 The calyx is often superior, with the lobes 

 always valvate ; the petals inserted on the 

 calyx are often fringed or divided ; and the 

 stamens as many or twice as many as the 

 petals, rarely more, inserted within them 

 with erect anthers. The ovary has two or 

 more cells ; and the fruit, either inferior 

 or enclosed in the calyx, has one or few 

 seeds. The order contains about fourteen 

 genera and is divided into two distinct 

 tribes : Rhizophoreo? proper consisting of 

 the genus Rliizophora, and a few small ones 

 separated from it, all maritime trees known 

 as mangroves, whose seeds are without 

 albumen and almost always germinate 

 before falling off; and Legnotidece (which 

 see), trees or shrubs not strictly maritime, 

 with usually smaller flowers, and albumi- 

 nous seeds not germinating before they 

 fall. The chief genera of this tribe are Ca- 

 rallia, Gynotroches, and AnstrutTieria in Asia 

 and Africa, and Cassipourea in America and 

 Africa. 



RHIZOPHORA. This genus gives its 

 name to the family Rhizophoracece, and is 

 more familiarly known by that of Man- 

 grove. The species are trees, inhabiting 

 the muddy swamps close to the sea-shore 

 in tropical climates. Botanically they are 

 distinguished from neighboming genera 

 by their four-parted calyx, four sharply- 

 pointed petals, eight to twelve stamens, 

 with short filaments and anthers contain- 

 ing several little pits filled with pollen, and 

 a partially adherent ovary, the adherent 

 portion containing two cavities each con- 

 taining two ovules, and the free portion 

 solid fleshy and gradually tapering into a 

 style. 



Theirchief interest, however, arises from 

 their peculiar mode of growth and of ger- 

 mination. Dr. William Hamilton has pub- 

 lished an interesting account of them in 

 the Pharmaceutical Journal, from which we 

 extract the following : ' In the economy of 

 Nature the Mangrove performs a most 

 important part, wresting annually fresh 

 portions of the land from the dominion of 

 the ocean, and adding them to the domain 

 of man. This is effected in a twofold man- 

 ner: by the progressive advance of their 

 roots, and by the aerial germination of 

 their seeds, which do not quit their lofty 

 cradle till they have assumed the form of 

 actual trees, and drop into the water with 

 their roots ready prepared to take posses- 

 sion of the mud, in advance of theirparent 

 stems. The progression by means of the 

 roots is effected by fresh roots, which 

 issue from the trunk at some distance 

 above the surface of the water, and arching 

 downwards penetrate the mud, establish- 

 ing themselves as the pioneers of fresh 

 invasions of the retiring element. In this 

 manner the plants, after their descent 

 from the parent trees, continue during 

 their early years to advance steadily for- 

 ward, till they have attained a height of 



about fifteen feet, and gained a position 

 considerably in advance of their parent 

 trunks. After this, fewer additions are 

 made to the roots, but the head begins to 

 expand in every direction, spreading its 

 branches on all sides. These branches in 

 their turn send down long slender roots, 

 like those of the banyan-tree (Ficusindica), 

 which rapidly elongating descend from 

 I all varieties of height, and reaching the 

 water penetrate the mud, becoming in 

 ; time independent trees: thus a complicated 



labyrinth is at length formed.' 



I These mangrove-bogs are the certain 



! indicators of a malarious locality, inasmuch 



I as they prevent the escape of the unhealthy 



miasma. The natives scramble along from 



root to root, without ever trusting their 



weight to the boggy soil below. To these 



I roots the oysters and other molluscs ad- 



| here, and are brought into view as the tide j 



goes down, thus verifying the statement of j 



old travellers that oysters grew on trees. 



All parts of these trees contain an abun- 

 dance of tannin, and hence they are very ! 

 serviceable to tanners. The bark is like- ! 

 wise employed by dyers, yielding with salts 

 of copper and iron, olive, brown, rust and 

 slate-coloured tints. The bark has also 

 been used medicinally as an astringent 

 remedy. In the West Indies and the Mau- 

 ritius the leaves and roots of some of them 

 are employed by the fishermen as poultices 

 for wounds caused by certain fish and ve- 

 nomous animals. 



The fruit of R. Mangle is said to be sweet 

 and edible, and the fermented juice to be 

 made into a kind of light wine. In Borneo 

 mangroves furnish the best firewood, and 

 a coarse bitter salt is extracted from their 

 aerial roots. In the Philippines, and also 

 in the West Indies, the bark of some of 

 the species is used as a febrifuge. The 

 genus well deserves its technical name of 

 ' root-bearer,' [M. T. M.J 



RHIZOPHYLLUM. A name proposed by 

 Newman for the Polypodies referred to 

 Phleb'odium and Pleopeltis. 



RHIZOPOD, or RHIZOPODIUM. The 

 mycelium or spawn of fungals. 



RHIZOPOGON. A genus of hypogynous 

 Fungi, agreeing with Melanogaster in hav- 

 ing root-like fibres running over the sur- 

 face, though not moist within, but dry like 

 a piece of porous bread-crumb. We are not 

 aware that the British species are eaten, 

 though sometimes produced in abundance. 

 R. pmvincialis is greedily devoured by the 

 peasants in Provence. One species is found 

 in the United States, and the genus occurs 

 also at the Swan River. [M. J. B.] 



RHIZOS. In Greek compounds = root. 



RHIZOSPERMA. Azolla. 



RHIZULA. The young root of mosses 

 and lichens. 



RHODACTINTA. The well-known Bar- 

 nadesia rosea has been separated from the 

 others of that genus under this name. It 

 differs from Barnadesiain having straight 



