101 
Rhi'zula — The roots emitted by the sporulea 
of Mosses, &c. 
Rhodo-lex:'cus— A combination of red and 
white. 
Rhombifo'lius— Where the leaf is ihoin- 
boiclai. Rhom'boiu, Rhomboi'dal, 
RHOMBE'US, RhOMBU-’OK'MIvS, Rhom- 
BOi'DEt^a, Rhomboida'ijh— Rudely ap- 
proximating to the form of a rhomboid ; 
that is to say, to a quadrangular figure 
(not a sqtiare) whose sides are equal. 
(See the foliage of a strong healthy 
plant of the Sida weed.) 
Rhtnchos'porus— Where a fruit termi- 
nates in an elongated projection. (See 
nuts of Rliyncho»pm\i auim^ a common 
sedge.) 
Right-hakdeo— 8ee “ Dextrorsum.” 
Ric'tls ( a grinning)— Synonym for “Faux” 
in i)ersoiiate flowers. 
Rig'id, Ki'gidus— Stiff, with slight or no 
flexibility, as the American Aloe 
leaves. 
Ri'ma — A cleft ; an ostiolum which has the 
appearance of u small cleft or chink. 
RiJtA'Tiis, Rimo'sus— F ull of clefts ; 
where the surface is covered with 
cracks or Assures. 
Ri'MiFORit — Having a longitudinal chink or 
furrow. 
Rin'ge5t, Rix'gens — G rinning. A bila- 
biate corolla whose lips Are widely 
separated. 
Rjpa'rius (Belonging to banks) — A plant 
whose natural station is the sides or 
banks or watercour.ses. 
Ri'pis, or Riti'pis, Rhi'pidos— A fan. 
(See PolijporMn rhipidium.) 
Rivcla'ris — E ither growing in water- 
courses or on their banks. 
Robcsta — R obust, as GreviHea rok<5fa, 
the Silky Oak, 
Root— The root, or descending axis, is that 
part of a plant which grows down- 
wards from the stein, divides and 
spreads in the earth or water, and ab- 
sorbs food through the extremities of 
its branches. They ordinarily produce \ 
neither buds, loaves, nor flowers. Their ; 
branches, called when slender | 
and long, proceed irregularly from any 
part of their surface. Although roots 
proceed usually from the base of the 
stem or stock, they may also be pro- 
duced from the base of any, especially 
if the bud lie along the ground, or is 
otherwise placed by nature or art in 
circumstances favourable for their 
development, or, indeed, occasionally 
from almost any part of the plant. 
They are then often distinguished 
as adventUiouSi but this tenn is by some 
applied to all roots which are not in 
prolongation of the original radicle. 
Roots are fibrous when they consist 
chiefly of slender fibresj tultrons^ when 
either the main root or its branches are 
thickened into one or more short fleshy 
or woody masses called tuOcTs; tap- 
roots^ when the main root descends 
perpendicularly into the earth, emit- 
ting only very small fibroms branches, i 
The stocks of a herbsceous perennial, 
or the lower parts of the stem of an 
annual or perennial, or the lowest 
branches of a plant, are sometimes 
under grtmnd and assume the appear- 
ance of roots ; such, however, arc called 
rhizome^, and may always be distin- 
guished fnuu the true root by the 
presence or production of one or more 
buds, or leaves, or scales. Although 
the root is ciinstructed generally on the 
sanie plan as the stem, yet the regular 
organizatirm, and the difference be- 
tw-een Exogens and Jiindogens is often 
disguised or obliterated by irregu- 
larities of growth oi by the pro- 
duction of large nuantitie.s of cellular 
tissue filled witn starch or other 
substances. There is seldom, if ever, 
any distinct pith ; the concentric circles 
of fibro-vascular tissue in Exogens are 
often very indivStinct or have no re- 
lation to seasons of growth, and the 
epidermis has no stomates. Roots grow 
in length coiistanily and regularly at 
the extremities only of their fibres, in 
proportion as they find the requisite 
nutriment. Their tibies proceed irregu- 
larly from any ])art of their surface 
without i>revious indication, and when 
their growth has been 8topi»ed for a 
time, either wholly by the close of the 
seasem or partially by a deficiency of 
nutriment at any particular spot, it 
will, on the return of favourable cir- 
cumstances, he resumed at the same 
point, if the growing extremitios be un- 
injured. If during the dead season, or 
at any other time, ihegrowingextremity 
is cut off, dried up, orotherwise injured, 
or stopped by a rock or other t»bstacle 
opposing its progress, lateral fibres will 
be formed on the still living portion, 
thus en.T,bling the root as a whole 
to diverge in any direction, and travel 
far and wide when Inred on by appro- 
priate nutriment. This gr(*wth is not, 
however, by the successive formation, 
of terminal cells attaining at once their 
full size. The cells first formed on a 
fibre commencing or renewing its 
growth will often dry up and fonn a 
kind of terminul cap, w’hich is pushed 
on as cells are formed immediately 
under it ; and the new cells, constituting 
a greater or lesser portion of the ends 
of the fibres, remain boine time in a 
growing stale before they have attained 
their full size. The functions of the 
root are— first, to fix the plant in or to 
the soil or other substance on which it 
grows; second, to absorb nourishment 
from the soil, water, or air into which 
the fibres have penetrated (or from 
other plants in the case of parasites), 
and to transmit it rapidly to the stum. 
The absorption takes place through the 
young growing extremitie.s of the fibres, 
and through a peculiar kind of hairs or 
absorbing organa which are formed at 
or near tho.se growing extremities. The 
transmIsaioD to the stem is through the 
