For August, 1922 



2i9 



Departments of Foreign Exchange and Book Reviews I 



WISTARIAS 



AMONGST vigorous climbing plants there is notliing more 

 beautiful than a well developed Wistaria in full blossom, 

 particularly when it has been allowed a good deal of freedom, 

 and has rambled over a tree or large building practically un- 

 checked. Wistarias are easily grown and hardy enough for wall 

 cultivation throughout the greater part of the British Isles, while 

 in the warmer parts they succeed admirably in the open, given 

 a large bush or tree over which they may ramble. The genus 

 contains but a few species, and of these two are so superior to the 

 others in general worth that they are almost exclusively chosen. 

 They are amongst the most popular of all climbers for planting 

 on verandas and pergolas, for in these positions the long, drooping 

 racemes of fragrant flowers are seen to the best advantage, 

 whilst they are also suitable for many other positions. Given 

 moderately good and well-drained, loamy soil, their cultivation 

 offers no serious problems, for they grow well from the time they 

 are planted. Soil of a very rich nature may result in too lux- 

 uriant growth and moderate flower production; therefore, it is 

 unwise to manure the ground heavily in which Wistarias are to 

 be planted. Moreover, in places where the root-run is restricted 

 flowers are usually produced more freely than where there is an 

 unlimited area of good soil. Free-growing plants against walls 

 have to be pruned to keep them within bounds, and in such cases 

 it is wise to encourage a system of short, sturdy, spur-like growth, 

 such as may be seen on stunted plants grown in pots for green- 

 house decoration in Spring. Constant cutting back of secondary 

 branches may be expected to result in growth of this description. 

 The same remarks apply to plants grown on pergolas, but when 

 growing freely over trees or large bushes pruning may be left 

 entirely alone. There are several means of propagation. Branches 

 may be layered into sandy soil. Cuttings of ripe shoots a foot 

 long may be inserted out of doors in Autumn, or shoots may be 

 grafted indoors in Spring upon sections of root. 



W. chinensis is the most familiar plant. It is a native of 

 Northern China, and was originally grown in this country about 

 a century ago. It is capable of reaching the top of very high 

 buildings or covering large trees, but by a system of root re- 

 striction it can be grown for many years as a bush a few feet 

 high, and be expected to flower freely each Spring. The flowers 

 are mauve in color, very fragrant, and borne in racemes each 

 8 inches to 12 inches long. 



IV. muttijuga. — Although not so well known as IV. clunciisis. 

 this is an equally desirable plant, and is particularly well adapted 

 for planting on pergolas and other supports, where its recemes 

 can be displayed to the greatest advantage. It is very popular in 

 Japanese gardens, and is introduced in works of art by Japanese 

 artists. It is said to have been introduced to European gardens by 

 way of Belgium soon after the middle of last century, but it has 

 only attained popularity in the British Isles within the last thirty 

 years. It grows almost as large as ff. chiuciisis, and is ratiier 

 similar in leafage, but has much longer and less dense racemes 

 of fragrant mauve flowers. The racemes are often between 3 

 feet and 4 feet in length, and are produced with the greatest 

 freedom. 



IV. hmchyhotrys, W. frutcsccns. and )'V . Japonica are other 

 species that have been described and are occasionally cultivated. 

 They, however, are quite overshadowed by W . chinensis and W. 

 multijuga for general purposes, and can only be recommended for 

 gardens where a collection of species is desired. 



Early in July the shoots produced by the main or leading stems 

 should be pinched back to within a foot or little more of the main 

 stem, in order to check the rampant growth. These shoots will 

 again break into growth from the buds behind where the shoot 

 was stopped, and after these shoots have grown a few inches 

 they should also be stopped. The result of this will be the pro- 

 duction of flower-buds at the formation of the shoots first stopped. 

 Early in the following Spring these shoots should be cut back 

 to within five or six eyes of the main stem, the young growths 

 from these eyes to be treated as those of the previous year. 

 By treating in this way long racemes of flower will be pro- 

 duced. — Gardening Illustrated. 



COMMON-SENSE PRUNING 



IT is decidedly encouraging to see signs appearing of more com- 

 mon-sense methods of pruning amongst our modern horticul- 

 turists. I have been pleading for more reasonable and more 

 scientific methods for many years, and I was particularly pleased 



to see that your correspondent. ".\ Scottish Gardener,'" describes 

 the old methods as barbarous. He is quite right ; and it is rather 

 strange that many intelligent gardeners do not discover for them- 

 selves that the pruning of fruit trees on the same plan as the 

 trimming of a garden hedge is not the way to produce abundant 

 crops of good fruit. I am sorry, however, to see that "A Scottish 

 Gardener" falls into the common error of stating that if a shoot 

 is pinched back, "the sap would be diverted to other portions 

 of the tree where it would be of more service." Such an idea 

 is entirely erroneous, and until some of the old fashioned ideas 

 about "sap" are got rid of progress with scientific pruning and 

 treatment of fruit trees will be slow. 



.\s a matter of fact, sap cannot be so diverted. It is quite 

 rue. of course, that if any of the branches of a tree are removed 

 while the roots are untouched, the root system is then larger 

 in proportion to the branches than it was before, and is therefore 

 capable of supplying more water and dissolved soil food to the 

 tree — if it requires it, or if it can use it. But this is the crux of 

 the whole matter. A plant cannot make any use of the sap — 

 that is, of the soil food — unless it has leaves in which to use it — 

 and the very fact of removing the leaves by cutting off a shoot 

 prevents the sap being utilized. 



The sap taken up by the roots consists of a very watery 

 solution of chemicals — that is, of various salts of phosphoric acid, 

 potash, lime, magnesium, etc.. some of which are in the form of 

 nitrates, and these salts are dissolved in at least 1,000 times their 

 weight of water. Before these salts can be of any use to the 

 plant they must be carried up to the leaves or other green 

 parts of the plant, where, first of all, the surplus w-ater is got rid 

 of by evaporation, and the salts are then built up by the living 

 cells of the leaves into proteids and other materials used by 

 the plant in its growth. At the same time the leaves and other 

 green parts are manufacturing starch and sugar from the car- 

 bonic acid of the air, and some of the water ; and this, along with 

 the materials elaborated from the salts brought up from the 

 roots, is then carried, mostly downwards in the bark, to where 

 it is required for the formation cf new shoots, leaves, buds, 

 fruit, wood, and roots. If the plant is strong and vigorous, 

 more of this elaborated material is made than is necessary for 

 the daily requirements of the plant, and this surplus is stored 

 up for future use in the bark and in the medullary rays of 

 the wood. 



It is from this stored- up material that the plant starts to swell 

 its buds and produce new leaves and roots in the Spring, and 

 not from any flow'ing of the root sap. as is commonly supposed. 

 I was very pleased to see this fact recognized by one of our 

 well-known horticultural w'riters the other day, who seemed to 

 have been convinced of the truth of it by observing that a 

 cut-off branch can produce new leaves, and even flowers, without 

 any connection with the soil at all, and therefore without any 

 flow of sap. 



These things are worth thinking about, and any practical 

 gardener who thinks them over must see how they bear upon 

 pruning. If the leaf-bearing area of the plant is too much re- 

 duced, it stands to reason that the plant is unable to make enough 

 starch and sugar, or to get rid of the surplus water in the sap, 

 and to build up enough proteids and other materials that it 

 requires. It therefore has none to spare for storing up. or even 

 for making fruit buds, well-ripened shoots, new wood, and new 

 roots. It may not have sugar and other materials to put into 

 the fruit it happens to be bearing. It is true that a plant may 

 be producing too much growth ; but this is generally due to the 

 soil containing too much nitrogenous plant food, and the plant, 

 with that eye to the future which it always has strongly devel- 

 oped, is bent on making all the growth it can while the favor- 

 able conditions last. But the gardener is after fruit, not luxuriant 

 growth, so he checks this by curtailing the supply of stimulating 

 food by root pruning. He is working at the wrong end if he lets 

 the tree take up all the soil food it can, and then atternpts to 

 check it by removing the foliage, so that it cannot manufacture 

 the necessary starch, sugar, proteid, etc., that it needs for the 

 production of healthy wood, new fruit buds, and ultimately 

 fine fruits. — Gardening Illustrated. 



LARGE-FLOWERING PANSIES 



MUCH has been written concerning the culture of Pansies, 

 but this has been mainly concerned with Spring sowing and 

 Summer and Autumn flowering. A few observations should now 



