716 



GARDENERS' MAGAZINE. 



November 5, 1 g 98 



Plant Roots and Plant Food. 



Th 



B 



Blech 



In the interesting controversy going on in the Gardenkrs' Magazine I have headed this article in the plural, despite the fact that a 

 between our esteemed friends "Lux" and Mr. J. Riddell, " Lux " states only one British species, because the varieties of that sDer s 

 that " roots do not create food, but food creates roots," while Mr. Riddell marked in character that, if found abroad, some of them would 655 S0 



— .i. mntQ rr«i e f nn A K„f f««J — 4. be regarded as specific forms. Considering the tough textur e f tainl >' 



green nature of the fronds, and the pretty contrast afforded^ " 



e species is not more freduemiu 

 seen under culture, that is, in moist, shady nooks and corners SI 

 drought, its greatest enemy, cannot penetrate. 



maintains the reverse order " that roots create food, but food does not 

 create roots." My own opinion is that both are right and both are wrong. 



In the first instance, food creates roots, because if there was no food 

 in the seed sown there would be no growth of roots. But roots having 

 once been established, go on accumulating plant food from the stores 

 within he soil or from the atmosphere. If we took a quantity of rocks, 

 such as we find in various parts of the earth's surface — granite, slate, 

 quartz, limestone, &c. — and after grinding them to different degrees of 

 fineness, were to mix them together in different proportions, we could from 

 the known composition of these various rocks produce soils which would 

 contain the most important mineral constituents of plant food in very 

 different proportions. Assuming that we purposely made one soil as 

 rich as we could in this mineral food, one as poor as we could, with two 

 others in intermediate stages, and we left them exposed to the ordinary 

 influences of sun and rain — provided the area was sufficiently large — we 

 should find that the seeds of plants carried by the winds and other 

 agencies would spread and grow upon these soils with very different 

 degrees of rapidity. The character and amount of the vegetation would 

 differ greatly on the different soils, and the largest amount would be 

 found on the soil where the plant could obtain the largest amount of 

 mineral food. 



There being no carbon or combined nitrogen in the soil, the first 

 plants would be entirely dependent upon the food in the seed and what 

 they could obtain of these substances, directly or indirectly from the 

 atmosphere, Rain water always contains ammonia, and the plant and 

 the soil may condense a certain further amount from the atmosphere ; 

 but growth, even in the soil richest in mineral food, would at first be 

 small, as the decomposition of carbonic acid and fixation of carbon would 

 be limited by the amount of combined nitrogen which the plant could 

 obtain from the sources mentioned ; and it would be much greater where 

 the most abundant mineral food existed, as every particle of the available 

 nitrogen would be there used up ; while where there was less mineral food 

 some of the combined nitrogen might pass through the soil and be lost. 



Every year a certain portion of the vegetable growth dies off ; leaves 

 and branches fall, and portions of the roots decay. Part of the organic 

 matter which falls upon the surface of the ground returns again to the 

 atmosphere, but a certain part remains, and, added to that which decays 

 underground, becomes available for future growth. The atmosphere of 

 the soil, which at first differed little from that which exists above it, 

 becomes highly charged with carbonic acid, which decomposes the 



corners, wher» 



drought, its greatest enemy, cannot penetrate. The fronds as I hi 

 said, are of two forms, one set, the barren ones, being shaped lik* 

 double, broadly toothed comb, the teeth of which are blunt and se^ 

 closely together on the midrib, and tapering in length towards both ends 

 m the shape of long slender lances. These barren fronds spread out 

 into a circle, and are sometimes considerably over a foot in length. Their 

 colour is a dark and shining green, and texture so hard and tough that 

 the popular name of the Hard Fern is fully justified. The fertile fronds 

 on the other hand, grow perfectly erect, are longer than the barren ones 

 and much more slender, the comb teeth being reduced to almost midrib 

 This difference persists through all varieties save one, called Blechnum 

 spicant anomalum, in which all the fronds are slightly fertile and 

 narrowed. ^ The fructification is very peculiar, apart from its confinement 

 to a special set of fronds. On examination it is seen that the spore 

 heaps extend the entire length of the pinnae, or comblike teeth, in two 

 lines, one on each side of the midrib, and that a thin, skinlike cover 

 springs from each side of each line, so that the spore cases or pods lie in 

 a deep furrow. This independent cover or indusium distinguishes 

 Blechnum from its near relative Lomaria, in which the edges of the 

 comblike teeth are turned over to form the cover, while in Blechnum they 

 are placed as an independent margin all round. This being so, it is 

 curious that some of our most popular authorities call our native species 

 Lomaria, ignoring altogether the clear specific character which has 

 determined the separation of the families. 



Blechnum spicant is a very widely spread fern in the British Isles, and 

 frequents hedgebanks, moorlands, glens, and forests, and indeed may be 

 found everywhere where plenty of moisture and leaf-mould and an 

 absence of lime (its special aversion) and 



vandal (its particular foe) 



fair 



the peripatetic fern 

 chance of existence. 



give it a 



Under culture it does well in many soils, if they be free from lime, and 

 soft water alone be supplied. A fine yellow friable loam, with a liberal 

 admixture of leaf-mould or peat, and some silver sand to keep it open, 

 suits the fern well, and once so installed it will thrive for many years with- 

 out a shift. Its habit is to spread by short stolens or offsets, so that in 

 time a clump is formed, and when well established there are few decora- 

 tive plants to surpass a good cleanly grown Blechnum spicant, with a 



K f ,^Ll°i!^ nd ! hUS y *" h l y £ ar ?l° re and . 1 m 1 °re of the nkrogen cr0 p 0 f decumbent barren fronds spreading round in a large rosette, and 

 „ — - — * c i - -«---«- r - ^ a dozen or so tall spikes of the fertile ones to set them off by contrast. 



The species, as I have said, has been by no means chary in afford- 

 ing good sports or varieties, some beautifully tasselled, some branched as 

 well, some beautifully cut, the combteeth being combs themselves ; and 

 others contracted, congested, or varied in other ways. In every case, 

 with the one exception above cited, these peculiarities present themselves 

 associated with the two forms of fronds, and are often so exaggerated in 

 the fertile ones, owing to the contraction. As usual, nearly all the 

 varieties have been found wild, though we owe the most beautiful of all, 

 known as Airey's plumosum, to a sowing from a merely saw-toothed find, 

 B. s. serratum. This, if well grown, is one of the grandest British ferns 

 we have, displaying wide, triply-cut fronds two feet long in profusion. A 

 plant I exhibited some years ago at the R.H.S. Fern Conference was so 

 beautiful that competent judges could hardly be persuaded it was ot so 

 normally simple a species. One of my own finds, B. S. concinnum 



collected by each generation of plants becomes available for the genera- 

 tion that succeeds it. 



The nitrogenous capital of a soil, which represents to a considerable 

 extent its fertility, thus depends, as a rule, on the bulk of the previous 

 crop residues. The present fertility of a soil is, therefore, in great 

 measure a consequence of its past root growth. The organic matter in 

 a fertile soil, say in a pasture turf, derived chiefly from root growth, is 

 continually undergoing oxidation by various agents in the soil, the 

 general result being its conversion into the simple substances, water, 

 carbonic acid, and nitric acid. The vegetable root residues left by 

 previous crops are thus reconverted into plant food, and made fit to 

 support the life of a new generation of plants. It is consequently true 

 that when rootlets come in contact with soil in which there is an abund- 

 ance of plant food they will be developed with far greater rapidity than 

 in neighbouring portions of earth in which less food is to be found. 



To test this point Nobbe took some heavy clay, and divided it into 

 two equal portions. One of these was left without manure, to the other 



was added a full supply of manure, 

 with the following results : — 



Red clover was planted in each, 



Unmanured 

 Fully manured 



• • • 



■ ■ • 



• • • 



• • • 



Weight of ] 

 Grains. 



431 

 592 



Weight of I 

 Grains. 



• • • 



• • • 



• • • 



30 

 60 



The two boxes of the experiment were found to be filled throughout 

 with vigorous roots, though, naturally enough, the roots were more 

 abundant in the fertilised earth, and weighed twice as much as the roots 

 in the unmanured soil. Further, it may be mentioned that Professor 

 Corenwinder planted a number of beets in a circle two feet in diameter, 

 and pushed down a bit of oilcake an inch or so into the soil at the centre 

 of the circle. Some months afterwards he found that several of the beets 

 bad ^ent out horizontal rootlets as far as the oilcake, which was covered 

 with a complete mat of capillary rootlets. One or two of these side rootlets 

 had passed through a course of sixteen inches before reaching the oilcake. 



Professor M. C. Potter, M.A., in his work on "Agricultural Botany," 

 says, "Tae root in many cases forms an excellent repository for the 

 various reserve materials which are manufactured by plants for use on a 

 future occasion. This is especially the case among herbaceous biennial 

 or perennial plants, which live in countries where either warm and cold, 

 or else wet and dry, seasons alternate with each other, and whose stems 

 die down during the period unfavourable to growth. 



in these plants the leaves manufacture during the period advantageous 

 to plant life more material than is required for immediate use. This excess 

 01 material is in many instances stored up in the roots, and forms the re- 

 serve fund from which stem and leaves are constructed in the next spring. 



10 sum up the matter in a few words : (i) Plant roots will not grow 

 m sterilised soil unless food be added from external sources ; (2) Roots 

 navmg once established themselves in a soil increase the store of available 

 plant food by their excretions, their root sap, and even in their death by 

 decay and the nitrification of their products 



Harpendetu v r t WILLIS. 



Druery, is a small grower, but has the comb transformed into an even 

 string of tiny green scallop shells, the fronds being ribbon shaped, ana 

 only a quarter of an inch wide. Mr. Barnes found one, B.s. lineare, inwnicri 

 the fronds are scarcely divided at all, being narrow and strap-shapea , 

 while another find of his has sharply-pointed, slender teeth, ana a 

 radiating, spiky crest at the frond tip— B. s. multifurcatum Barnes \m 



B. s. trinervis coronans). . . . , , , „ u n *tnm 



Mr. Phillips, of Belfast, found a curious form, in which the two bottom 

 teeth of each frond are transformed into smaller fronds, making a so 

 of trident. This variety covers a large area in the Mourne Mountains 

 Dr. Kinahan's Irish find of B. s. ramocristatum is finely branched ana 

 tasselled, and several finely tasselled varieties have been louna d> . • 

 G. B. Wollaston and others. I have two very good W^g^^T 

 crested character, one found by a quarryman (Sinclair) jS^bS 

 and another by a lady friend in Devonshire, both thor ^"; etie * 

 B. s. Aithinianum and B. s. cladophorum are curiously brantheuj. 

 but do not rank amon^ the gems. There have also been finds ot mo 

 leafy character. B. s. imbricatum is one, Hartley's crisp.ss.mum anot 

 -a veritable dwarf, even the hard little fertile fronds not exceeding 

 three inches in height, springing from a rosette of the same aiamei ^ s ^ 

 All those named are well worthy of culture, and, if my "JgfSoty 

 attended to as regards the aversions and needs of the plants, in ^ 

 will well repay the little care required. B. spicant « J s £~ heatf 

 winter as any other time, and that is an advantage ; it neeu> 

 and, given only congenial harbourage, will always pay its rem. 



CHARLES T. DRUERV, KLb, 



sight 



summer, 

 mark in 



-------- «•« w* w 



of orange scarlet 



ours make an effective 



or 



wo at a time for weeding, the intensity of the ^f.^^ there » 

 We should hardly consider a ™ sight * of this description delightful, w 

 no accounting for taste. 



