QUERIES AND ANSWERS. 179 



nitrogen produces large crops of roots aggregating a large amount of 

 sugar, but seemingly not in proportion to the nitrogen supplied. An 

 excess of nitrogen gives great leaf luxuriance, and keeps the plants unripe 

 late into the season. As an adjunct to nitrogen as a food to root crops, 

 potash is very important, the increase of sugar being much influenced by 

 the amount of potash. 



991. Q. Can I get good crops of truck by using 600 to 700 pounds of super- 

 superphosphate to the acre ? phosphates, 



A. Generally you can look for good results, but you don't get enough 

 potash in ordinary superphosphate. As a rule, years of use and almost 

 entire reliance upon superphosphate have brought about on garden soils 

 a potash impoverishment which seriously affects results. Potash is 

 required largely by corn, clover, potatoes, and is eagerly assimilated by 

 all garden vegetables, in fact it is never out of place. Don't adhere 

 entirely to superphosphates. Its makers don't profess to furnish much 

 potash. You can get potash in wood ashes, and it is safe to apply one 

 ton or fifty bushels to the acre, or you can get it in muriate of potash, 

 using 200 or 250 pounds to the acre. Nitrate of soda can be applied, using 

 300 or 400 pounds to the acre. The urine of animals is especially rich in 

 potash and should all be saved by absorbents placed in the barnyard, and 

 the manure pile should be kept under a shed and not be exposed to the 

 leeching effects of rain. 



992. Q. Is the sweet potato of the same family as the yam. Sweet 

 A. No, they are of distinct genera, the sweet potato being, it is thought, Potato. 



a native of Central America. In 1526 it was in general cultivation in St. 

 Domingo and other West India islands. Botanically it belongs to the 

 Convolvulus family of dicotyledonous plants. The edible portions are 

 true roots. In China there is an edible root somewhat resembling it but 

 of the Ipomsea family. The various species of yams cultivated in the 

 United States belong to the widely scattered Dioscorea family and are 

 believed to have been brought from Africa. They are monocotyledonous 

 plants, markedly distinct in this particular from the dicotyledonous sweet 

 potato, and the yams are distinct also in their flowers, as in them the 

 sexes occur on difi"erent plants, while in the sweet potato the sexes are 

 found on the same flower. The edible portion of the yams are under- 

 ground stems, while in the sweet potatoes they are roots. The distin- 

 guishing qualities between the sweet potato and the yam is too well 

 known to need description. 



993. Q. Do most garden vegetable plants fertilize or pollenize them- Pollination. 

 selves. 



A. A great many do ; but quite as many absolutely require the aid of 

 insects to carry the pollen from one flower to another, or to loosen parts 

 of the flowers of monojcious plants that fertility may take place. A 

 familiar example is found in the bean, pea, and clover plants, where the 

 visitation of an insect at the right time causes the stamens to discharge a 

 cloud of pollen. It is said that bees when visiting the flowers of beans 



