ucr, J, idm.j 



THB TROPICAL AGRICULTURIST, 



^i 



2. We should not expect plants having a very 

 thick or hard epidermis to root, as the necessary 

 absorption through thin-walled cells could not take 

 place. Nor would the root branches be well able 

 to pierce the epidermis did they commence to bud. 



3. We should not expect portions of the stem in 

 which there was a great amount of woody or thick- 

 ened tissue (in addition to little outer absorbing 

 tissue) to callus readily enough to allow much change 

 of growth before the cutting decayed. 



Naturally we ask ourselves, Can we formulate any 

 rules which will be fairly correct in regard to the 

 chances of cuttings of roots " striking " ? 



We require the formation of leaf-buds here in addi- 

 tion to the formation of feeding roots. The giving 

 off of fibrous roots we may consider even more likely 

 as were they in a slightly undeveloped state I believe 

 they might grow without callusing of the cutting. 



But it will be considerably more difficult for stems 

 or leaves to be given off. 



1. A stem requires a pith or central medullixry 

 tissue as well as woody tissue. This we have seen is 

 generally absent from roots. 



Could the stem-buds, if pre.sent or dormant, find 

 enough woody tissue, and also obtain pith perhaps 

 from the outer layer, as they do when branching off 

 from a root-stock, as in Lysimachia, we might fairly 

 consider that our root cuttings would generally suc- 

 ceed. That they sometimes callus without producing 

 leaves is a known fact. 



Leaf Buds from Roots. 



An examination of Primula cashmiriaua and Drosera 

 ha? led me to think that the reason why these roots 

 [stocks] give off leaves so readily, is because there 

 is no central pith required ; the growths are " stemless." 



Dodecatheon will produce little rosettes of leaves 

 from every root stock if once the crown has decayed 

 away after flowering. This may not be a fair ex- 

 ample of root-propagation, as it may be thought 

 that some portion of a very slightly developed stem 

 would be attached to the upper part of each root 

 and Irom this leaves were given off. 



Ehizomes. 



Wherever there are dormant leaf-buds, as on the 

 rhizomes of Helleborus and Draciena, there is no 

 difficulty in getting plants from small cuttings, but 

 these are not true " root-cuttings." There are cases, 

 as in Ipecacuanha, where stems are produced from 

 annotated root-cuttings, where also there is no pith. 

 It seems rather that we may take it as a fairly correct 

 rule, that where stems are required from our root- 

 cuttings there must be pith. In Dandelion and Dock 

 when cut accross wc know there is the power to 

 give off leaves. 



We might consider here how universal in the 

 vegetable kingdom is the readiness of certiiiu tissues 

 to emit roots. There nKist be a trace of a harder 

 tissue than that which exists as an absorbing agent at 

 the exterior of all roots. They are given otf: — 1, 

 from scales, as in the Lilium auratum, Pinguicula 

 caudata, and many others; 2, from bulbils borne 

 among the flowers (in allium) or from the axils of the 

 leaves, iu Lily or Banunculus Ficaria ; 3, from soft 

 leaves, us Begonia or Kyophyllum : from succulent 

 leaves, as in some species of Echeveria, &c.; i, from 

 almost any part of the stems and branches if treateil 

 carefully, from the end of Fern fronds, as in Adiantum 

 Edgeworthi ; these organs, developed especially to 

 feed the plant, are very freely given off from the 

 other orgaus of vegetable growth. 



Places from whence Koots grow out. 



We are not surprised to see, then, that from many 

 lower parts of stems roots and stems (the latter either 

 ascending or creeping) are gi^■en off one above the 

 other very indiscriminately. This can be seen in 

 hosts of examples, from palm (Phwuix) to bog-loviug 

 creeper. 



Roots prefer to grow out from places as in the 

 swollen norles iu stem?;, where there is more tibro- 

 vascular tissue, and as in the Philodendrou, where, 

 though having most of its bundles scattered through 

 the softer tissue of the istem, there is yet a conceutric 



layer below the epidermis of more substance, there- 

 fore more reaily giving off roots. 



1 may mention that Lysimachia verticillata is au 

 excellent example, showing the roots growing from 

 the dense woody ring iu the lower part of the stem if 

 cut across, whilt the branching stems have a growth 

 from the seemingly much-coloured pith (re.'in in the 

 pith y) passing into them in the centre of the woody 

 tissue. 



The DisTiNt iions between Stem and Roots, 



La.stly, before pas.sing ou to consider the bearing 

 of these facts upon cultivation, we will roughly try 

 and note whether we find any distinction between 

 stem and root, so nearly, as we have seen, do they 

 resemble each other. 



1. The growth of the stem upwards away from 

 the more damp eai'th towards the light, stands out 

 in great contra.st with the tendency in all roots to 

 grow towards moisture, and as a necessary cousef|uence 

 towards shady or dark| places. 



This growth i)i different directions is in direct 

 relation to the differing functions of the two organs — 

 stem and root. The one bears flowers and leaves 

 spread out to all the influences of air and light — 

 the other as a general thing chiefly developed to 

 absorb water and food which may pass into the 

 whole plant. 



2. As to whether there is any difference in exter- 

 nal or internal structure I belit-.ve is au undecided 

 point. Internally the cells are, to all less thorough 

 investigation at least, just the same. We certainly 

 find that p.th is oftenest present in stems and absent 

 from almost all roots, except as in some trees where 

 they branch from the trunk, the pith being present 

 because growing as continuation of that in stem. 

 This pith (though useful in giving more bulk to the 

 stem, from which the leaves may more readily pass 

 off) is needless to the root. 



We can all see that the root is colourless generally 

 though when growing in the air at times, as in Chio 

 rophyton, it becomes green, or hard, brown, and stem- 

 like, with bark on it. The epidermis in many stems 

 whilst green has also breathing places, or " stomata." 

 It is sufficiently evident that there would be no need 

 for these in terrestrial roots, although botanists point 

 out among aerial roots, as in some Orchids and iu 

 Mangrove, the marks of similar stomata. 



3. As to the power in stems, and the absence of 

 this power among roots, to give off leaf-buds, which 

 we have already referred to somewhat fully, I may 

 ad<l that according to the functions of a root we do 

 not need the presence of leaf-buds, and they are never 

 present in true absorbing roots as we should perhaps 

 restrict the term though whether present iu storage 

 roots at all frequently I cannot yet make out. 



It is certainly difficult to draw a hard and fast line 

 between these two organs, especially when in so many 

 of our best text-books of systematic botany we read 

 of '• roots," and find such able to produce leaf-buds 

 plentifully under certain favourable conditions. I think, 

 however, that the greater number of botanists will 

 look upon roots and stems both as complex structures 

 having similar rudimentary structures (in the thin- 

 walled celH, although these may be developed differ- 

 ently according to their functions. — Gcvrdenera' 

 Chronicle. 



EuBBER IN Brazil. — The Para statistics not 

 having come to hand, onjy those for Amazonas 

 are published, viz. : — 



weight. value. 



188-2-83 .... 718,137 kilos. 2,253,369* 



1883-84 .... 1,040,358 „ 2,564,431 



1884-85.... 1,412,407 „ 2,505,580 



The minister suggests that the municipalities 

 and provincial legislatures should take steps to 

 replant the tree, in the proper situations, near 

 villages, not only to prevent the destruction of 

 this source of wealth, but also by reducing thf' 

 cost of harvesting to place the article on a belter 

 iooting as regardij foreign rubber,--i?/o Neivs, 



