BETTER FRUIT 



AN ILLUSTRATED MAGAZINE PUBLISHED MONTHLY IN THE INTEREST OF MODERN, PROGRESSIVE FRUIT GROWING AND MARKETING 



Pollination of Plants 



By Dr. A. J. Cooke, State Commissioner of Horticulture, Sacramento, California 



YOU will each and all recall the 

 mechanism of a flower in its best 

 development. As you know, each 

 part of the floral envelope is a modi- 

 fied leaf. The close student often sees 

 positive proof of this in a petal that is 

 also at the same time a stamen. A 

 double flower results from a reversion 

 of stamens in a multistaminate flower 

 like the rose back to petals. The outer 

 circle of floral leaves — the sepals — are 

 still leaflike as they usually retain the 

 green color of the normal leaves. 

 These sepals, except as they enfold and 

 protect the bud, function solely as 

 leaves. The next whirl of the floral 

 envelope just within the calyx forms 

 the corolla, which is made up of three 

 or more variously colored leaves 

 known as petals. These are what give 

 beauty to the flower and are of real 

 service to it in attracting insects to the 

 important work of pollinating the 

 flower, which is our theme at this 

 time. Often the flower is very irregu- 

 lar, the separate petals varying greatly 

 in form. This peculiar conformation, 

 as Darwin explained years ago, has 

 directly to do with pollination and so 

 interests us greatly in this discussion. 

 Within the corolla are the stamens, 

 the male equipment of the flower. 

 These may be the same number as the 

 petals when they are opposite or alter- 

 nate with them. There may be a great 

 number, as in most rosaceous flowers. 

 Each stamen has a stem-like stalk, 

 often thread-like, hence called the 

 filament, and a head knov»n as the 

 anther. The anther bears the male 

 element, the pollen, a fine dust of vary- 

 ing color, though more frequently yel- 

 low. Each pollen grain is a cell and 

 corresponds to the sperm cell in ani- 

 mals. In the very axis of the flower 

 we find the pistil, usually only one 

 but soiuetimes as many as there are 

 petals, and rarely, as in the strawberry, 

 many. The pistil is the female organ 

 of the flower. Its bulbous base is 

 known as the ovary, which bears a 

 slender appendage, the style. The lat- 

 ter is tipped with an unctions enlarge- 

 ment known as the stigma. In the 

 ovary grows the ovules, the plant eggs 

 if we may so speak — the female ele- 

 of the plant. Like the pollen 

 and the egg, these are cells 

 when fecundated by the pollen 

 develop into the seeds. The 

 unctions stigma captures and 

 the pollen grains. From each 

 grain there develops a thread 

 pushes down the entire length 

 of the style and enters an ovule. This 

 is fecundation and is absolutely neces- 

 sary to the formation of a seed. The 



ments 



grain 



which 



grain, 



sticky 



holds 



pollen 



which 



seed is the partially developed plant — 

 an embryo — and as the animal egg can- 

 not develop without the sperm cell, no 

 more can this ovule or plant egg with- 

 out the presence of this pollen thread. 

 We thus see that no fecundation, or in 

 other words no pollination, is the 

 equivalent of no seeding, usually no 

 fruitfulncss. 



Many plants are dioecous; that is, 

 each flower is either male or female, 

 not both. Of such are the oak, the wal- 

 nut and some varieties of strawberries. 

 In some cases, as the pepper tree, the 

 sexes are on different trees or plants. 



Features of this Issue 



POLLINATION OF PLANTS 



FTJNDAMENTAL PRINCIPLES OF 

 CO-OPERATION IN AGRI- 

 CULTURE 



UNFERMENTED APPLE JUICE 



PREVENTION OF WOOD DECAY IN 

 FRUIT TREES 



CORRECT COST OF ORCHARD 



MANAGEMENT 



CONDITIONS AFFECTING BLIGHT 

 AND THEIR CONTROL 



THE EVOLUTION OF THE CIDER 

 INDUSTRY 



TIME TABLE FOR GIRLS WHO 

 PRACTICE CANNING 



In all such cases of course, even though 

 a flower is fertile to the pollen of its 

 own species, there nuist be marriage 

 priests, as Darwin styled the bees, to 

 carry the pollen from flower to flower 

 or from tree to tree. In rare cases, as 

 in some varieties of strawberries, all 

 the plants are pistilate. Here pollen 

 must be brought to them from other 

 staminate plants. 



In many monoecious plants where 

 the flowers are perfect with both 

 stamens and pistil in the same flower, 

 the flowers are infertile, or will fail 

 to fruit, or at least to ijroduce seed un- 

 less cross-pollinated. We say such 

 flowers are self-sterile, or sterile to 

 their own pollen. Our clovers and 

 many, probably most, of our fruits are 

 of this class. Most irregular flowers 

 are so formed as to require cross- 

 pollination. The very conformation 

 of the flowers prohibit self-pollinalinn 

 and insure cross-pollination through 

 the visits of nectar-loving insects. 

 Often plants like the Bartlett pear are 

 self-sterile in one locality and fertile 

 to their own pollen in another. I have 

 reason to believe also that plants may 

 at one time be self-fertile and the same 



plants at another time be self-sterile. 

 It is also interesting to note that the 

 pollen of some varieties is more potent 

 than others of the same species. Thus 

 among cherries the Black Republican, 

 Black Tartarian and seedlings are 

 found, in some sections at least, to 

 be strong pollinizers. The same may 

 be said of Drake's seedling among 

 almonds. The experiments of the Ore- 

 gon station show that the Bing, Lam- 

 bert and Napoleon (Royal Ann) are 

 inter-sterile. Of course in our plant- 

 ing it would be most convenient to set 

 varieties in solid blocks, but it would 

 not be wise or scientific. We should 

 always mix varieties, being careful to 

 select varieties that bloom at the saiue 

 time, also to secure those that are inter- 

 fertile. Suppose the Bing or the Lam- 

 bert or the Napoleon are thought to be 

 the most profitable varieties, then a 

 few sour cherries, or Black Tartarian 

 or other ellicient jjollinizers, should be 

 sparingly intermingled with the more 

 desirable varieties. The same is true 

 of our almonds. If we wish the Ne Plus 

 Ultra and the IXL, we may well mix in 

 liberally here, as the Drake's seedling 

 is a very desirable variety, for it has 

 been found to be an etficient pollinizer. 

 Very likely locality is important in this 

 matter, and it is wise in planting to 

 note what varieties are desirable for 

 market and at the same time are inter- 

 fertile each with the other in each lo- 

 cality. At present we are not suffi- 

 ciently informed as to the potency of 

 pollen from the several varieties of our 

 fruit, but we know enough to make us 

 sure that it is wise in all cases to mix 

 varieties, and it may be wise in some 

 cases to plant sparingly of undesirable 

 varieties to make sure that we provi<le 

 for ellicient pollination. 



From what we have seen above we 

 note that ellicient agents in this w'ork 

 of [lollination nuist be good flyers, must 

 desire and seek often the nectar of 

 flowers and must be very numerous, as 

 the flowers to be ijollinated are multi- 

 tudinous. In such flowers as the straw- 

 berr>- each blossom has several ovules 

 to pollinate, and if any are missed the 

 berry may be deformed. Of course all 

 free-llying, sweet-loving insects are 

 valuable to the horticulturist or agri- 

 cidtiirist as collaborators in the pol- 

 lination end of seed and cro]) produc- 

 tion. All bees, honey, bumble and 

 other wild bees, most if not all wasps, 

 ants though han(li(api)ed by the ab- 

 sence of wings, many moths and most 

 butterflies, such diptera as syrphus 

 flies, nectar-loving beetles and not a 

 few homoptera aid in this work of 

 pollination. 



