for November, l')20 



ill 



article of faith among many professional gardeners tliat old melon 

 seed — of conrse, provided it is not too old to germinate — produces 

 more pistillate tlovvers and therefore more fruit than is produced 

 by plants grown from new seed, and with the idea of artificially 

 aging seed they sometimes carry it about in their pockets for 

 some time previously to sowing. So far as I know, this theory 

 has not been subjected to any scientilic test, although such test 

 would be simple to carry out provided the a,ge of the seed ex- 

 perimented with was definitely known. 



Among diiecious plants, those more commonly seen in gardens 

 are the various species of Ilex (Holly); also, as a pot plant in 

 the Xorth. the Acuba japonka. sometimes called the .\cuba Lau- 

 rel, but it bebjngs to the Dogw^ood family. These plants are more 

 ornamental in their berried state, for which purpose pistillate 

 plants are the first necessity, and these must also have some 

 staminate plants growing near them for the production of pollen. 

 In growing the Acuba under glass it is necessary to shake a flow- 

 ering staminate plant over the flowers of the others. If the 

 former produces flowers much before the latter, then the pollen 

 may be collected and kept in a dry state until the pistillate flowers 

 are ready. The pollen will not. however, keep lunger than a few- 

 weeks. 



In the animal kingdom, spontaneous movement, either volun- 

 tary or involuntary, is an attribute of life, generally looked upon 

 as a matter of course. In the animal, the brain is conceded to be 

 the motor which puts into motion the power or force which is at 

 the back of all movement. While plants have no brains, yet 

 much evidence of brain power is to be foiuid in connection with 

 them by reason of the fact — amongst others — that they exhibit 

 the faculty of being able to move voluntarily in various ways and 

 directions. 



This power of volinitary movemeiu can be c>liser\ed in co.inec- 

 tion with the germination of pollen .grains. 



When pollen grains come into contact with the outward end 

 (stigma) of a pistil, which in a ripe state exudes a sticky, 

 sugary substance, germination takes place in the form of the 

 growing out from them of a tube, which tube grows down the 

 pistil into the ovary and by this means the setting of good seed 

 is b.rought about. 



If pollen grains are placed upon a suitable medium cm the slide 

 of a microscope the tubes will be seen to grow out in all direc- 

 tions, Init if a piece of ripe stigma is placed among them upon 

 the slide the tubes will soon deviate from their indifferent paths 

 and will grow tow'ards the stigma. Similar phenomena — in prin- 

 ciple — is sometimes to be seen in connection with the germination 

 of seed when the root, if it emerges towards the surface of the 

 ground, will turn round and grow downwards; also, in the way 

 in which roots, of trees and shrubs especially, will grow tow-ards 

 and invade rich soil, and towards water. This power of growing 

 towards congenial media is very widespread among plants and is 

 kr.own as ehemiotaxis. Ihe idea being that the pollen tubes and 

 roots are attracted by the chemical nature of the medium to 

 which they respectively grow. Without disputing the possible 

 correctness of this idea, it does not appear to be improbable that 

 some other force, namely, brain power, may be behind this power 

 of movement, especially when taken in connection with other 

 evidence which cannot be gone into now. 



The transfer of the pollen from the stamens to the pistil is 

 termed pollination and is to the gardener of the greatest im- 

 portance in connection with fruit production. Botanically, the 

 term fruit is applied to all ovaries, or seed cases, wdiatever form 

 they may assume : popularly, the word fruit is used only in con- 

 nection with those ovaries wdiich become enlarged, fleshy and 

 edible, like the apple. 



In the case of some perfect flowers, the stamens and pistils are 

 so arranged that the pollen falls directly upon the pistils, but in 

 numerous instances the arrangement is such that self-pollination 

 is impossible and the introduction of pollen from outside is neces- 

 sary, which is known as cross-pollination. This cross-pollination 

 is brought aliont mainly in two ways : by wind and by insects. 

 Certain iilants. such as the grasses and conifers, are always wind- 

 p()llinated. The flowers of these are generally inconspicuous, 

 without nectar or fragrance, and they produce a great abniKlance 

 of liglit, dry ])ollen, which is sometimes carried many miles by a 

 strong wind. The pistils of these plants are comparatively long 

 in the case of corn — in which case what we call the silk is the 

 pistils — very much so: also, in many instances thev are very 

 feathery and arc thus adapted to catch the flying pollen. 



On the ober band, flowers of insect-pollinated plants are more 

 or less showy, and have either nectar or fragrance, or both, which 

 attracts the insects and. in going from one flower to another, they 

 carry pollen with them and cross-pollination is accomplished. 



Cross-pollination is known to be beuelicial even in tlie ease of 

 those plants bearing self-fertile flowers; that is, flowers in which 

 the ovule can bc_ fertilized by the pollen produced in its own 

 flower. The benefits noticed by the cross-pollination of self-fertile 

 flowers are larger and more numerous seeds, producing more 

 vigorous plants, and in the case of fruits, they are invariably 

 larger, Xature favors cross-pollination in perfect-flowered plants 



by numerous adaptations which prevent self-pollination; as by so 

 locating the st:inieiis that the |)ollen is not readily deposited on 

 the stigma of ilvj same flower, or by maturing the pollen either 

 before or after the receptive stage of the stigma. In some cases 

 pollen is infert'le upon the stigma of the same flower or plant 

 which is ciuite fertile on stigmas of other jilants of the same 

 species. 



This condition of self-sterility is not usually due to a deficiency 

 in either the (|nantity or the quality of the pollen, or to defective 

 pistils. The pcdlen grains often germinate upon the sti.gma, but 

 tertili/alion does iku take place. \\ by this is so is not clearly 

 understood. It canr.ot be degeneration of the pollen, because two 

 self-sterile varieties arc invariably fruitful when planted together. 



Self-steril'ty is very important in connection with the produc- 

 tion of certain fruits, h is common in varieties of apples, pears, 

 plums and grapes, but is uncommon or unknown in cherries, 

 peaches, currants, ,go(iseberries, strawberries, rasplierries or other 

 like lierries. Regarding strawberries, soine of the most produc- 

 tive varieties yield little or no pollen and are even without 

 statnens ; they are. therefore, unproductive unless growing near 

 varieties producing plenty of pollen. 



Self-sterility does not appear to be a constant factor in any 

 variety, as those wdiich are self-sterile in one locality are fre- 

 quently self- fertile in another not very. far away. In reviewing 

 the evidence in this connection from various authorities, Fletcher 

 .says: "It is quite evident that the degree of adaptation of a 

 \ariety to its environment has much to do with its ability to fruit 

 abundantly from its ow'u pollen." It is not,_ therefore, possible 

 to make a complete list of fruit varieties under the headings of 

 self-fertile and self-sterile respectively which w'ould be applicable 

 to all localities. There are. however, a few varieties which are 

 generally quite dependable as being self-fertile. .Among apples 

 these are, Ben Davis, Baldwin, Rhode Island Greening, Oldenburg, 

 ^'ellow Transjiarent and Yellow .Vewtown. 



While there does not seem to be so much positive self-sterility 

 among pears, many are uncertain, and the only kinds usually 

 considered reliably self-fertile are .\ngouleme (Duchess). Bosc, 

 Flemish and Seckel. 



Practically all varieties of Japanese and native plums are self- 

 sterile, but while most European varieties are self-sterile in Eng- 

 land, the^e varieties when grown here are generally self-fertile. 



Many \arieties of grapes are self-sterile, the most strongly slf- 

 fertile ones being Concord, Delaware, Diamond, Niagara, Winchel 

 and Worden. 



Quinces and peaches are always self-fertile. 



With the possible exception under some conditions of the apple, 

 all pcUination of fruits is done liy insects and almost entirely by 

 bees. Hooper estimates that e-ghty per cent of cross-pollination 

 of fruits is done by tlie hive bee. fifteen per cent by various wild 

 bees, especially the Bumlile Bee. and five per cent by miscellaneous 

 insects. The importance of bee-keepin,g in connection with fruit 

 production cannot be overestimated, and it is worth while to 

 keep bees for this purpose alone, irrespective of the surplus honey 

 they may give. To avo'd destruction of bees, spraying for the 

 larvre of the codlin n:oih should only be done just before the 

 flower'; open and soo:i after the petals have dropped, never when 

 the trees are in full flower. 



\\ bile cross-pollinatio 1 appears in most cases to cause a self- 

 fertile variety to produce larger fruit than when it is fertilized 

 by its own jwlleii, there does not appear to be any other influence 

 exerted by it so far as the fruit itself is concerned. For cross- 

 pollination to take place between two varieties it is. of course, 

 necessary that the bloom at about the same time. 



The flowers of some plants can only be pollinated through the 

 agency of a special insect. This is the case, for example, with 

 Red Clover (Trifoliuiii pnih'iisc), which never produces seed in 

 countries or districts wdiere the Bumble Bee is absent. In Xew 

 Zealand, for nistance. this bee had to be imported and naturalized 

 before Red Clover seed could be produced. 



In Xature an absolutely seedless spccirs is unknown : seedles 

 varieties are not. however, uncommon, although there are not 

 many plants upon which edible fruit develops" without the fer- 

 tilization of the ovule resulting in the formation of a seed with 

 a living embryo. 



Seedle'^s varieties of fruit have generally in the first instance 

 resulted from a sport, and when seedless fruits of any kind have 

 a greater economic value, such as is the case with bananas, citrous 

 fruits and the grape from which the .seedless raisins are ob- 

 tained, the sport has to be increased by suckers, grafts, or buds. 



Seed production exhausts the plant more than any other of its 

 life processes, as the plant must store up in the seed prepared 

 and highly concentrated rich material for the food supply of the 

 embryo. 



Many plants die immediately after they have produced seed, 

 and nearly all annuals and biennials do so after flowering, whether 

 they have been allowed to produce seed or not : perennials are 

 always more or less weakened by seed production. 



The flowering .season of most plants can be greatly prolongc'l 

 (Cniiliiiiicd on page 379) 



