570 
THE GARDENING WORLD. 
May 8, 1886. 
garden for additional funds, and in a short time nearly 
£4,000 was forthcoming. In July, 1885, a large portion 
of the old structure was pulled down, and an extensive 
block of new glass houses was built (see illustration on 
p. 565). At the present time, the collection of plants 
in these gardens cannot be surpassed, excepting at 
Kew. Orchids receive marked attention, and visitors 
to the gardens next week, on the occasion of the first 
Orchid show held in Birmingham, will there see an 
extensive and well-grown collection. Mr. Latham 
deserves more than passing praise for the good work he 
is doing, and for the admirable cultural condition of 
the vast collection of plants under his care. He has 
troops of friends in Birmingham and the surrounding 
districts, and few men are held in higher estimation 
or more kindly regard by all who know him. 
- ■—***« - 
ON THE ROOT-STRUCTURE OP 
PRIMU L ACEiE. * * 
By Dr. M. T. Masters, F.K.S. 
For practical purposes it is very serviceable to 
consider a living plant in the light of a piece of 
mechanism, constructed and put together to do certain 
■work as efficiently and as economically as circumstances 
permit. The comparison may serve our purpose with¬ 
out it being necessary to point out where it fails, and 
wherein lies the great difference between a machine 
begotten of its predecessors, and who had the like 
structure and endowments with irself, self-sustaining, 
supplying its own power from sun, air, and water, 
built up and adapted by its own energy, and one 
constructed by the art of man, dependent on artificial 
means for its support and its power, and with no innate 
faculty of self-adjustment to varying circumstances. 
Availing ourselves, therefore, of the comparison we may 
proceed to discuss what it is our machine is called 
on to do, how it is enabled by its conformation to do 
what is required of it, and, incidentally, how we may 
help or mar its action. The Primulaceae will afford us 
as good illustrations of these matters as any other family 
of plants. It is the group which is expressly selected to 
furnish a text for these remarks, and which, moreover, are, 
as prescribed, to be limited to a part only of the machine 
—the root. It is permissible, however, on such an 
occasion to use the term root in the broad sense in 
which it is usually employed by gardeners, and notin the 
more accurate and strictly limited sense in which it is 
made use of by r physiologists. 
The Requirements. 
‘VVhat, then, is our machine—the root—called on to 
do ? In all cases to lay hold of the soil and secure the 
plant mechanically. How it does this will be 
sufficiently though incidentally illustrated later on, and 
is not a subject on which we as cultivators need linger 
long. The plants w^e have now to deal with may be 
lifted out of the ground by frost, but they are hardly 
likely to be washed away by floods or uprooted by 
winds. To pot firmly and press the crown firmly into 
the soil in transplanting are lessons which common 
experience teaches, lessons which the conformation of 
the root to be presently noted, do but accentuate. 
Another universal duty imposed on the root is to 
feed the plant. This is soil-food and there is air- 
food. The leaves, stimulated by light and heat, 
collect and transform the one ; the roots, influenced 
by heat, absorb and digest the other. How they do 
these things is beyond the purpose of this paper to 
explain, but reference to any modern botanical text¬ 
book, and in particular to the truly marvellous revel¬ 
ations contained in the chapters on root movements in 
Darwin’s The Power of Movement in Plants, will 
supply the information and afford indications of the 
processes of absorption, of solution, of fermentation, 
of transformation, which, with or without the agency 
of minute Bracterian organisms, constitute each root- 
tip, each root-hair, a laboratory and a workshop. 
Each root-tip, each root-hair, moreover, is as sensitive 
as a nerve, not only responding to a touch, but trans¬ 
mitting impressions from the spot touched to adjoin¬ 
ing cells. It is as mobile as a muscle, turning towards 
what is useful to it, bending away from what is noxious 
or obstructive, threading its way through the soil, and 
-adapting itself to circumstances as if it really possessed 
intelligence. It acts like the brain, says Darwin ; 
*For tlie communication of numerous specimens illustrative 
of these notes I am specially indebted to Mr. Dewar, of the 
Royal Gardens, Kew ; Mr. Barron, of Chiswick ; Mr. Correvon, 
of Geneva ; Mr. Douglas, and other friends. For some of the 
drawings I have to thank Mr. Sandgren, of Kew. 
and truly as a sentient organ, receiving and transmit¬ 
ting impressions and directing the course of growth 
and movement, it wrnuld be hard to say wherein its 
inferiority to the nervous system of the lower animals 
consists. 
In the case of annual plants which live their life 
within the compass of a few weeks or months, there is 
little else for the root to do than to secure the plant 
in the ground and to go in search of food and turn it 
to account when found. 
But in the case of perennial plants such as most of 
our Primulaceae, another duty becomes incumbent—- 
that of providing a store-place for water and for food. 
The food so stored, principally starch and allied sub¬ 
stances, is not absorbed directly by the root and 
packed away, but partly by root-action and soil-food, 
partly by leaf-action and air-food, is manufactured in 
the leaves and afterwards transferred and deposited in 
the root or in the root-stock. 
A similar formation of starch takes place in annual 
plants, but it is used up in process of growth, or 
stored in the seed to be turned to use by the seedling 
plant when it begins life on its own account. In any 
case the storage requirements of an annual are small 
in comparison with those of a perennial. To ascer¬ 
tain how and in what manner the food is obtained, 
transformed, stored, and employed is surely to put 
ourselves in possession of information, of any that 
could be named, the most important for cultural 
purposes. 
Another phase of work which falls to the lot of 
the root (sensu latiori) to achieve is that of jrropaga- 
tion, and by observing how this is effected spon¬ 
taneously we may surely obtain some useful hints 
for our own artificial procedures. 
Such, then, in very general terms, is the nature of 
the work to be done ; such, in merest outline, are the 
requirements of the case. 
ThE Mechanism. 
In the following remarks it is proposed to give a 
few illustrations of the machinery by means of which 
the work just alluded to is done, for while the work is 
in all cases the same, the machinery by which that 
work is accomplished is manifold in detail. 
Annuals. 
Very few cultivated Primulacese come under this 
head. Some of the Androsaces and Anagallis are 
annuals; but speaking from a cultivator’s point 
of view, they might be passed over if it were not 
for one circumstance, frequently ignored or over¬ 
looked, though one of great importance—the fact 
that seedling plants even of those species destined to 
be perennial are, to all practical intents, annuals. 
Barring the slender resources stored up in the seed, 
the seedling plants have a little store to draw upon, 
and thus, like the annuals, they must have good food 
within easy reach, and be provided with rapid means 
of utilizing it else they wither away.* 
Centunculus minimus .—A weed no cultivator would 
bestow a thought upon, unless it were to compass its 
destruction, may, nevertheless, serve as a useful illus¬ 
tration. It sends down into the soil a slender tap¬ 
root, which speedily ramifies just below the surface, 
branches and branches again till it, as it were, invades 
a considerable area of soil. There are no great “hold¬ 
fast” roots—none are needed, but, on the other hand, 
there is a great multiplication of small fibres, and a 
consequent extension of absorbent surface. Notice, too, 
that there is no caulicle ; in other words, the radicle 
comes straight away from beneath the two cotyledons, 
without there being any perceptible internode (stalk) 
between the base of the seed-leaves and the top of the 
root, In a seedling Primrose may generally be observed 
the radicle, giving off branches, then an erect cylin¬ 
drical portion bearing the cotyledons or seed-leaves, 
but sometimes reduced to very small dimensions ; this 
is the caulicle or tigellum. Above the two seed-leaves 
is the plumule, consisting of the first leaf or leaves 
above the cotyledons. In these seedlings it is curious 
to see how, whilst the primary roots descend vertically, 
the secondary ones pass off horizontally. 
It is quite clear that the seed in Centunculus was not 
buried deeply, for the caulicle is a minus quantity. It 
is clear also the soil for such a plant should be light, 
5 “Some [seed] fell upon stony places, where they had not 
much earth : and forthwith they sprung up, because they had 
no deepness of earth : and when the sun was up they were 
scorched : and because they had not root, they withered away.” 
Matthew, xiii., 5, 6. 
open, rich, and well drained. Contrast this with the 
germination of Primula reticulata, in which not only 
is the tigellum very long, but the two cotyledons are 
also raised on long, erect, or ascending stalks, as if the 
plant grew in the clefts of the rocks, and had a long 
distance to thrust its seed-leaves into the light and air 
The requirements of the seedlings are, it need hardly he 
said, of the same character. We all know the care 
that is requisite to secure the germination and the 
rearing of these delicate organisms. 
“In the morning sow thy seed, and in the evening 
withhold not thine hand.” Eccles., xi., 6. 
The mode of growth of the Androsaces is similar. 
They are, it is true, for the most part not annuals, hut 
in their root-growth some of them (the csespitose species) 
follow the mode of anmrals. The seedling plants have 
roots of the annual character, with a long radicle 
giving off numerous branches. The adult plant has 
little provision for storage, hut consists of a dense tuft 
of leaves, from the axils of some of which proceed long 
slender runners, like those of a Strawberry, and which 
bear at their ends a tuft of leaves like the parent from 
which they sprung. From the under surface of this 
tuft proceed roots like those of the Centunculus, and, 
like them, destined, not for any lengthened use, hut 
only for a temporary purpose ; no long time indeed 
elapses ere the tuft throws out new runners and thus 
repeats in another generation the process of its own 
genesis. It would seem from this peculiar mode of 
growth that the Androsaces speedily exhaust the area 
in which their roots spread, and having done so 
haste— 
“To-morrow to fresh woods and pastures new.” 
Milton, Lycidas, t. 193. 
Whether this is not an indication of value to the 
cultivator I leave to others who have had more experience 
to decide. My own want of success with these plants 
cannot in fairness be attributed only to neglect of the 
indication ! 
Perennials. 
In these, as for annuals, there is need for daily supplies 
during the growing period, and further, there is the 
necessity for replenishing the stores. It is necessary, 
therefore, to consider the root-growth of these plants 
from two points of view—that of food-collecting and 
that of food-storage. 
The actual absorption of water is, of course, effected 
in the same way in the roots of perennials as in those of 
annuals, but the perennial habit allows more time 
wherein to work, and frequently secures a wider root- 
range than is possible in an annual. In a perennial, 
cceteris paribus, the roots can travel further, or penetrate 
deeper in search of food, than in the case of an annual. 
In an annual the roots, as gardeners say, “keep at 
home,” and there is not much necessity for a system of 
conduits to convey the water from its source to the stem; 
but in perennials it often happens that the best food 
supply is at some considerable distance from the stem, 
and the consequence is that the fibrous roots collect the 
liquid from the feeding-ground, and convey it in so 
many conduits to the stem. The thicker root-fibres 
have, as everyone knows, little or no power of absorption, 
that faculty being mostly limited to the thinnest 
extremities of the root-fibies, and to the root-hairs 
(where present). Of course the number, length, and 
degree of branching of the roots depend very greatly' on 
the physical nature of the soil in which the plant 
happens to be growing— 
“Pinguibus hse terris habiles, levioribus illse.” 
But when due allowance is made for these circum¬ 
stances each plant has more or less its own distinct 
character. The roots of most species of Primula, for 
instance, are very different from those of Androsace, 
and indicate different requirements. But even in the 
same genus we get variations in this respect. In the 
common Primrose and Polyanthus, in P. cashmeriana, 
P. capitata, P. amcena, P. auricula, P. denticulata, P. 
nivalis, P. longiflora, P. cortusoides, &c., the roots are 
generally rather thick and fleshy, descending more or 
less vertically for some little distance without branching, 
and then giving off short nearly horizontal branches 
with few root-hairs (except in P. auricula) in which, in 
some cases at least, the roots are covered with a velvety 
coat of hairs. Such roots are not surface-feeders, but 
are capable of penetrating to a considerable depth in 
search of food, while their succulent habit and reserve 
store of water obviate the necessity for that dense net¬ 
work of fibrous roots that other species present. 
Primula rosea, P. Kaufmanniana, P. involucrata, 
