EHIZ] 



$TI)e Crea^ttrg of 28otan». 



974 



R. Cassytha is a common species in the 

 West Indies, where it grows from one to 

 six. feet long, and hangs from the branches 

 of trees. It has whorls of cylindrical 

 branches with blunt ends, the ultimate 

 branchlets being about three inches in 

 length. R. platycarpa, a native of Brazil, 

 has flat leaf-like brandies resembling those 

 of the genus Phyllocactus, the joints being 

 from four to eight inches long and about 

 one-and-a-half broad, with small distant 

 notches from which the dirty white flowers 

 are produced. [A. S.] 



RHIZANTHErE. One of the five classes 

 into which Lindley divides the vegetable 

 kingdom. It consists of plants destitute 

 of true leaves, but with short amorphous 

 stems parasitical on roots. The flowers, 

 which in some instances are very large, 

 are various in their structure ; and the 

 three orders composing the class, the 

 Balanophoracece, Cytinacece, and Raffle- 

 siacece, are by some botanists placed far 

 from each other in the vegetable system. 



RHIZINA. The young roots of mosses 

 and lichens. 



RHIZOBLASTUS. A term applied to 

 embryos which develope roots. 



RHIZOBOLACE^E. (llhizobols.) A small 

 order of dicotyledons, consisting only of 

 the two genera Caryocar and Anthodiscus, 

 which have been compared with Clusiacere 

 on account of the extraordinary size of the 

 radicle of the embryo with very minute 

 cotyledons, and the opposite leaves of one 

 genus. The leaves are, however, alternate 

 in the other genus, and the structure of 

 the flowers is so nearly that of Ternstrb- 

 miacece, among which there is sometimes 

 an approach to the same disproportion in 

 the parts of the embryo, that the Rhizobo- 

 lacece are now proposed to be considered as 

 a tribe of that order, differing both from 

 it and from Clusiacece in their digitately 

 compound leaves. The few species known 

 are all tropical American trees. 



RHIZOBOLUS. Caryocar. 



RHIZOCARP.E. The same as Marsilea- 

 cece. 



RHIZOCARPOUS, RHIZOCARPICUS. 

 Having a perennial root, but a stem which 

 perishes annually ; as herbaceous plants. 

 The sign of these is %. 



RHIZOGENS. Rhizanthece. 

 RHIZOGLOSSUM. Opliioglossum. 



RHIZOID, or RHIZOIDEOUS. Resem- 

 bling a root. 



RHIZOMA, RHIZOME. A prostrate 



rooting stem, progressively throwing up 



leaves. The name is applied among ferns 



to the creeping stem, which may be either 



superficial or covered with the soil, and in 



such a case must not be confounded with 



the true roots. The fronds are sometimes 



j articulated with the rhizome, and such 



i fern s are called by Smith Eremobrya ; some- 



| times they are permanently attached, and 



the ferns in which this is the case are called 

 Desmobrya. The distinction is, however, 

 not of the same importance as in phaeno- 

 gams; and if this character were adopted 

 as distinctive, closely allied genera would 

 be widely separated. The rhizomes of ferns, 

 like real stems, exhibit very different ar- 

 rangements of their several constituent 

 tissues. When these differences have been 

 more extensively studied, they will very 

 probably afford good characters for sec- 

 tional divisions. For an account of these 

 we refer to Berkeley's Introduction to Cryp- 

 togamic Botany, p. 514. [M. J. B.] 



RHIZOMANIA. An unnatural develop- 

 ment of roots. Many plants, as ivy, screw- 

 pines, figs, &c, without any indication of 

 disease whatever, send out roots from 

 various parts in the same way as trees so 

 commonly produce adventitious buds. In 

 the common garden fig, wherever it is 

 nailed to the wall, roots are sent out within 

 the bandwhich surrounds the stem. Their 

 development, however, as in the vine and 

 common laurel, usually indicates some- 

 thing wrong about the ordinary roots, in 

 consequence of which sufficient moisture 

 is not supplied to the stems and leaves, 

 and rootlets are thrown out from the 

 stem in search of it. In the laurel this 

 generally ends in death. Roots again 

 are frequently developed in little bundles 

 on the stems of apple-trees ; and as they 

 retain moisture amongst them, and their 

 tips in process of time decay, decomposi- 

 tion is setup, extending inwards till canker 

 is produced. [M. J B.j 



RHIZOMORPHA. A spurious genus of 

 Fungi, comprising a great number of root- 

 like productions which are nothing more 

 than particular states of Polypori,Eppoxyla, 

 &c. Many of these owe their peculiar flat- 

 tened character to the circumstance of 

 their growing between the bark and wood 

 of our forest trees, and thus being strongly 

 compressed in the course of their growth. 

 Other matters have been referred to the 

 same genus, which are merely the roots of 

 willows, elms, &c, or even of herbaceous 

 plants filling up drain- tiles or other cavities 

 where there is a constant supply of water. 

 Fries indeed thinks that there is one good 

 species of Rhizomorpha produced in mines, 

 a bad situation for an autonomous plant. 

 One great peculiarity of the supposed spe- 

 cies which grow in mines, or of some of 

 them at least, is their highly luminous 

 character, which is not exceeded by Agari- 

 cus olearius, or any other luminous fungus. 

 In the coal-mines near Dresden the species 

 are described as giving those places the 

 air of an enchanted castle ; the roof, walls, 

 and pillars are entirely covered with them, 

 their beautiful light almost dazzling the 

 eye. The light (which is apparently phos- 

 phorescent) is found to increase with the 

 temperature of the mines. [M. J. B.] 



RHIZOMORPHOUS. Resembling a root. 



RHIZOPHORACE^E. (RMzophorew, Man- 

 groves). An order of polypetalous dicoty- 

 ledons, allied in some respects to Cuno- 



