502 
THE GARDENING WORLD. 
April 6,1895. 
DO PLANTS EAT SOIL? 
It is a well-known fact that has come within the 
personal observation of every practical gardener, 
who is called upon in the ordinary course of his 
professional experience to deal with plants that have 
to stay in comparatively small pots for protracted 
periods, that as the pots become filled with roots 
there is a corresponding diminution in the bulk of 
the soil placed there in the first instance. We sup¬ 
pose that this has caused more than one gardener to 
wonder what has become of the soil of which the 
pot contained so large a quantity a year or so before. 
Accordingly, the question raised by “ C. B. G." on 
p. 440 of a recent issue of The Gardening World, 
viz., as to whether plants eat soil, is one that may 
well receive a few moments’ attention. On the face 
of it, this would seem to be a natural way of 
accounting lor the disappearance of such a large 
proportion of the compost. 
The idea that the plants eat the soil, that is to say 
that it passes into the system of the plant in a raw 
or solid state, cannot for a moment be entertained. 
Although Sir J D Hooker’s statement " that the 
food of plants is liquid and gaseous, and never 
solid” was made, as ” C. B. G.” states, twenty years 
ago, it may be still accepted as being correct and to 
the point. That it is impossible for plants to take in 
solids, except they being of a soluble nature are 
first dissolved in water, is an incontrovertible fact. 
A fact, moreover, that may easily be substantiated by 
a careful study of root absorption. In this all- 
important work it is the root hairs which act as the 
primary absorbing and conveying medium. A few 
moments’ careful consideration of what a root hair 
really is, as well as a few details concerning its 
structure, may, therefore, serve to throw a little 
light upon the subject. 
Root hairs are usually unicellular outgrowths 
from a single epidermal cell, the cell walls being ex¬ 
tremely thin, and the growth itself of very short 
duration. If young roots are carefully examined it 
will be seen that these hairs are most numerous a 
little way behind the growing points, but that they 
have entirely disappeared from those roots of older 
formation, thus limiting these to the function of 
acting as channels, whereby the crude material 
collected by the root hairs borne by the younger 
roots may be conveyed to the green parts of the 
plant there to be elaborated. With regard to the 
manner in which the root hairs perform the 
all-necessary work of absorption, Mr. Joseph W. 
Oliver, in his text book on ” Elementary Botany,” 
says that "the root hairs come into close contact with 
the particles of the soil, adhering to them very 
very firmly, so firmly that if the plant is carefully 
removed from the soil in which it is growing the 
roots will be seen to be covered with the adjacent 
particles. By this adhesion the root hairs are 
brought into close contact with the films of water, 
and the water, together with the dissolved food 
materials, gradually diffuses through the wall of the 
root hair and the lining layer of protoplasm into the 
vacuole or cell cavity.” 
From this it will be seen that the various elements 
contained in the various chemical compounds which 
the plant needs as food cannot enter the plant except 
in a state of solution, and that the water really acts 
as the vehicle, which after dissolving these substances 
serves to convey them to the green parts of the plant, 
where by the aid of the chlorophyll they are con¬ 
verted into starch, sugar, fats, and proteids, out of 
which are manufactured the complicated compounds 
cellulose protoplasm, etc. This, of course, does not 
refer to the absorption of carbon with which the root 
hairs have nothing to do, this being aborbed by the 
leaves as carbon diocide (C O a ) or carbonic acid gas, 
as it is familiarly called, and decomposed by the 
action of light, the carbon remaining fixed and the 
oxygen expelled. 
With regard to the ash of plants which always 
remains in a greater or less quantity after the 
dissipation of the more volatile constituents of the 
plant, viz., carbon, hydrogen, oxygen and nitrogen 
by fire. This always contains the elements potassium, 
calcium, magnesium, iron, and phosphorus, besides 
a quantity of sodium, manganese, silicon, and 
cnlorine, which may or may not be present. Now 
the student of plant life needs not to be told that 
each and all of these elements, carbons excepted, are 
supplied to the plant in the soluble form, water as 
before stated serving as the vehicle by which they 
are conveyed. As, therefore, all kinds of plant food 
must be dissolved in water before it is possible for 
them to pass through the closed membrane of the 
cell wall of the root hair it cannot be allowed that 
plants are capable of assimilating particles of solid 
matter. 
But if we look at the question in another light we 
may say that plants consume soil to some degree, 
inasmuch as they live upon the elements composing 
it to a large extent. The soils in which plants exist 
is necessarily formed by the decomposition of the 
various strata of rocks underlying them, these being 
usually broken up by the disintegrating influences of 
the atmosphere, such as rain, frost, etc., also with 
the addition of a quantity of humus furnished by the 
decomposition of animal and vegetable matter. Now 
if a plant is to thrive in the soil in which it is placed, 
either when that soil is contained in a pot or when 
the roots of the plant are free to ramble in the open 
ground, it is manifest that that soil must contain all 
the elements necessary to the life of that plant or 
failure will ensue ; in other words, the plant if it does 
not die will at best eke out a miserable and stunted 
existence. 
Thus when we pot plants which have to remain 
in the same state for some time we usually make the 
soil as good as possible, and as soon as the pot has 
become filled with roots and the plant food it contains 
more or less exhausted we have to assist the plant 
by the application of various manures, that is, if we 
wish to keep it in a healthy and vigorous state of 
growth. But we have already noted that certain 
constituents of the soil have been absorbed by the 
plant and their abstraction must, of course, involve 
a certain diminution in the bulk of the soil, although 
this may not be apparent or appreciable. There can 
be no doubt, however, that the most fruitful cause of 
the disappearance of the soil in cases of pot-bound 
plants is due to the washing of water during a long 
season, and in a less degree to compression. 
Worms, too, play a very important part, carrying 
as they do the soil either to the surface where 
it is removed in the form of worm casts or else con¬ 
veying it to the drainage where it is washed 
through. 
It must also be remembered that in pots where the 
roots form a perfect network, any water given sinks 
much more rapidly through the ball than it does 
when such a state of the roots does not exist, and 
sinking thus rapidly it exercises a correspondingly 
greater rinsing influence upon the soil in the pot. If 
anyone will examine the shingle upon which plants 
have been standing for a time his mind will soon be 
set at rest as to the probable cause of the disappear¬ 
ance of the soil, for every practical gardener knows 
from experience that if he wishes to keep shingle of 
this kind clean and free from soil it must be washed 
every now and again.—G. 
_ ,-»T - 
♦ - 
ORCHID DOTES ADD GLEADIDGS, 
By John Fraser, F.L.S., Kew. 
The Orchids described below were awarded Certifi¬ 
cates according to merit by the Royal Horticultural 
Society on the 26th ult. 
Bollea Schroderiana. Nov. sp .—According to 
the more modern system of classification, the Bolleas 
are now included under Zygopetalum, but whether 
the species under notice is included under that name, 
or kept separate, there can be no question it is a 
plant with flowers of large size and great beauty. 
The flowers are borne singly on peduncles arising 
from amongst a dense mass of roots, and have broad, 
obovate sepals and similar but smaller petals, all 
incurved, fleshy, waxy-looking, and pure white. In 
contrast to the concave appearance produced by the 
other segments, the lip is erect at the base, then 
spreads horizontally, with the lamina revolute at the 
sides and pale violet; a large ridged crest at the 
bend of the lip lies against the large, fleshy, white 
column. First-class Certificate. A large plant in a 
basket was exhibited by Messrs. F. Sander & Co., 
St. Albans. 
Batemannia peruviana Nov. sp .—Here again 
we have a representative of a group of Orchids form¬ 
ing a section of Zygopetalum. Several of the 
members of the group are of curious structure but 
beautiful, though comparatively uncommon in culti¬ 
vation. The tetragonal pseudobulbs are 2 in. long 
and bear a pair of lanceolate leaves at the apex as 
well as smaller ones or leaf sheaths at the case. The 
narrowly obovate sepal is brownish-purple with a 
circular stripe and a greenish tip, while the lateral 
ones are deeply concave and approaching one 
another, project in front of the flower. The ovate 
petals are similar in colour but have two circular 
streaks upon them as well as the apical green blotch, 
giving them a variegated appearance. The three- 
lobed lip is white, finely spotted with purple on the 
side lobes, and has some purple markings at the 
base of the revolute lamina. Though pretty it is not 
conspicuous. Botanical Certificate. Exhibited by 
Messrs. F. Sander & Co. 
Dendrobium Cordelia. Nov. hyb .—The seed 
parent of this hybrid was D. aureum crossed with 
the pollen of D. euosmum leucopterum, itself a 
hybrid. As is well known, the flowers of both 
parents are fragrant, and this is the case with 
D. Cordelia as might be expected. The sepals are 
of a soft creamy-white tinted with purple at the 
edge; the petals are twice as broad and a shade 
paler in colour. The ovate lip is creamy-yellow 
with a large, crimson-brown, radiating blotch at the 
base and covering about half of it. The terete stems 
are 6 in. to 12 im high. The soft and delicate shades 
of colour are the chief recommendations to this 
choice and charming hybrid. Award of Merit. 
Exhibited by Messrs. J. Veitch & Sons, Chelsea. 
Cypripedium Olenus. Nov. hyb .—This dwarf 
and pretty species was raised from C. bellatulum 
crossed with the pollen of C. ciliolare. The upper 
sepal is nearly orbicular, and rosy-purple with darker 
markings along the principal veins and shaded with 
green along the centre. The petals are broadly 
oblong and of a soft purple, marked all over with 
spots of a much darker hue. The lip is similar in 
shape to that of C. bellatulum, but of a rich dark 
purple and finely pubescent. The leaves are oblong, 
and dark green with paler markings. Award of 
Merit. Exhibited by R. I. Measures, Esq , (gardener, 
Mr. H. Chapman), Cambridge Lodge, FlcddenRoad, 
Camberwell. 
Dendrobium Donnesiae Nov. hyb. nat .— 
Whether it is so or not, the general aspect of this 
Dendrobium would give one the impression that it is 
a natural hybrid between D formosum and D. in¬ 
fundibulum or its variety D.i. JamesiaDum. Thestems 
vary in length from 2 in. to 12 in., the latter being 
the height of the last made growth, are furnished 
with oblong leaves and covered all over with short 
black hairs ; they are very stout and in that respect 
resemble those of D. formosum The sepals and the 
broadly rhomboid petals are white, the latter being 
not much smaller than those of D. formosum. The 
lip resembles that ofD. infundibulum in size and 
shape, and is white with a central band and heavy 
lines on the side lobes, all of a bright orange colour ; 
the edges of the lamina are dentate and undulated. 
The spur is long and decurved at the tip. Aw r ard of 
Merit. Exhibited by J. Bradshaw, Esq. (gardener, 
Mr. H. Whiffen) The Grange, Southgate. 
Dendrobium Schneiderianum —The parents 
of this hybrid were D. Findleyanum and D. aureum, 
the former being the seed-bearer. The stems show 
the influence of the latter in the elongated and 
obconical nodes or joints that are, however, greener 
and less flattened than in the original. The sepals 
are white, washed with pink, and the ovate, wavy 
petals are creamy-white with rosy tips. The lip is 
broadly ovate with an orange-brown blotch at the 
base, succeeded by a narrow white band and a pale 
purple tip. Award of Merit. Exhibited by E. 
Ashworth, Esq. (gardener, Mr. H. Holbrook) Hare- 
field Hall, Wilmslow. 
Bulbophyllum burfordiense. Nov. sp .—The 
flowers of this species are amongst the most 
remarkable in the genus. The upper sepal is oblcDg- 
oval, reflexed at the base then incurved again in the 
middle, of a tawny buff colour tesselated w'th white, 
and 4 in. to 5 in. long by in. wide. The lateral 
sepals are singular looking organs being turned on 
their edges vertically in the lower half while the 
upper half is turned or twisted with its upper surface 
downwards ; they are of a dusky yellowish hue. The 
miniature, movable lip is green, spotted with 
purple. The pseudobulbs are short, square, and 
terminated by one oblong leaf. Botanical Certifi¬ 
cate and a Cultural Commendation. Exhibited 
by Sir Trevor Lawrence, Bart, (grower, Mr. H. 
White), Burford Lodge, Dorking. 
