VARIEGATION 



VEGETABLE-GARDENING 3435 



spotting or marking is not constant in seedlings, often 

 being very different from the parent. In certain groups 

 of plants, which have for many years been selected on 

 account of the horticultural value of these markings, 

 the variegated condition has be- 

 come almost a fixed feature of the 

 plant, as in dracenas, caladiums, 

 and codieums. While the plants of 

 these genera are not usually propa- 

 gated from seeds, still when they 

 are so propagated, a large number 

 of seedlings show more or less varie- 

 gation. 



Darwin and many of the earlier 

 investigators believed that these 

 variations were started in the plant 

 by unfavorable nutritive conditions, 

 and much has been written on the 

 subject as to whether or not varie- 

 gations should be considered as 

 diseased conditions. 



The question as to whether a 

 variegated condition could be trans- 

 mitted to normal plants by budding 

 and grafting has also been much 

 disputed, but the weight of evidence 

 indicates that in many cases such 

 transmission certainly takes place. 

 This has been thought to indicate 

 the presence of some micro-organ- 

 ism, living either parasitically or 

 symbiotically in the plant, and 

 causing the changes known as 

 variegation. 



Investigations conducted by the 

 writer on the so-called mosaic dis- 

 ease of tobacco, which is a form of 

 variegation, and also on many other 

 forms of ordinary variegation, show 

 quite conclusively that the disease 

 is not caused by micro-organisms, 

 but is due to a deranged condition 

 of the nutrition of the cells. With- 

 out going into the details of the 

 matter, it may be said that the con- 

 dition is characterized physiologic- 

 ally by a marked increase 

 in the oxidation processes 

 in the cells, caused by the 

 presence of an abnormal 

 amount, or an abnormal 

 activity, of oxidizing fer- 

 ment in the protoplasm. 



These changes must, in 

 most cases, therefore, be 

 considered as pathological 

 in their nature, as the 

 vitality and vigor of the 

 plants are reduced as a 

 result. It is further evident that 

 the initial causes of variegation may 

 be quite diverse, some of the most 

 usual being seed of low vitality; 

 unsuitable nourishment, especially 

 a lack of elaborated nitrogen; rapid 

 growth in very moist soil; severe 

 injury to the roots during a period 

 of rapid growth of the upper parts 

 of the plant; severe cutting back, 

 and the like. 



Though started at first through 

 the influence of environment, varie- 

 gation, when of value horticultur- 

 ally, has in many cases been in- 

 creased and fixed by selection till it 

 has become almost a specific charac- 



3907. Kinds of variegation. Sansevieria 

 above and caladium below. 



ter in some groups of plants, and is considered in the 



botanical description of them. 



A word might be said in this connection regarding 



autumn coloration. The production of color in autumn 

 foliage is, as is well known, due in 

 part to the gradual destruction of 

 the chlorophyl when the leaves have 

 reached maturity and approach the 

 period of death, and in part to the 

 action of acids on anthocyanin. 

 Many of the destructive changes 

 which take place in the chlorophyl 

 are oxidation processes, the same as 

 occur in the cells of highly colored 

 variegated plants, and physiologic- 

 ally they are not very different from 

 the changes occurring in calathea, 

 caladium, codieum, and the like. 

 The approach of maturity in the 

 leaf, and the coming on of cool 

 weather in autumn, stimulates the 

 production of oxidizing ferments, 

 and the action of these and the 

 acids of the cell-sap on the chro- 

 mogen, or color contents of the 

 leaves, especially the chlorophyl and 

 anthocyanin, causes many of the 

 brilliant colors of autumn f oliage (p. 

 431)- ALBERT F. WOODS. 



VARNISH TREE: Kaclrevteria ponuru- 

 laia, Ailanthus aitissima, Rhut terniciflua, 

 and other plants. 



VASES: See Topiary planting and garden 

 architecture, VoL 5, p. 2675. 



VEGETABLE-GARDENING. In 



horticultural usage a vegetable is 

 an edible herbaceous plant or part 

 thereof that is commonly used for 

 culinary purposes. The product 

 may or may not be directly asso- 

 ciated, in its development, with the 

 flower: the root, stem, leaf, flower- 

 bud, partially developed seed-recep- 

 tacle, mature seed-receptacle, or 

 seeds (either immature or 

 mature), may constitute the 

 edible part. Some vege- 

 tables are edible only after 

 being cooked, others (such 

 as cabbage), are eaten either 

 cooked or raw, while others, 

 as melons, are used only in the 

 fresh state, and are really dessert 

 articles. In some countries, melons 

 and tomatoes are regarded as fruits, 

 though American usage classifies 

 them as vegetables. Although it is 

 difficult to make a general definition 

 that will include all vegetables and 

 exclude none, the use of the term 

 "vegetable" is so well understood 

 that there is little difficulty in mak- 

 ing proper application of it in com- 

 mon speech. 



All the art and science that has 

 to do with the growing of the plants 

 commonly called vegetables is popu- 

 larly known as vegetable-garden- 

 ing- The Latin term, olericulture, 

 is sometimes used in formal writings 

 as a synonym of vegetable-garden- 

 ing, but has never become popular. 

 Vegetable-gardening is usually con- 

 sidered as a branch of horticulture, 



