LYCOPERSICUM ESCULENTUM 551 



GENERAL MORPHOLOGY 



The tomato plant is grown in the United States as an annual, 

 and the length of time required for maturation of the fruit, after 

 transplanting into the field, ranges from 55 to 65 days for rapidly 

 maturing varieties, and from 85 to 100 days for the slowly growing 

 canning types grown in northern and central California. The 

 latter may not attain the peak of the harvest until 100 to 1x5 days 

 after transplanting. The variation in the size of the plant is 

 equally striking. In general, early varieties are small in stature 

 (16 to 18 inches in height) with a maximum spread of 4 to 4^^ feet, 

 while the slowly maturing forms are much larger, attaining a 

 height of 14 to 2.S inches and a maximum spread of 6 or 7 feet. These 

 figures refer to plants which have been grown without pruning. 



The Root. — The character of the root system is greatly modi- 

 fied by cultural practices. When grown from seed, without 

 transplanting, a strong tap root is formed which, according to 

 Weaver and Bruner (36), may grow at a rate of an inch a day attain- 

 ing a depth of nearly 1. feet. In actual practice, the plants are 

 started in seed beds and transplanted once or twice before being set 

 in the field so that the primary root is injured and a dense fibrous 

 system of lateral and adventitious roots is formed. After the final 

 transplantation to the field, the adventitious roots develop rapidly 

 and, in mature plants, may have a lateral spread of 5 feet, with 

 numerous large branches. These occasionally penetrate 3 to 5 

 feet, although the major portion of the root system occupies the 

 first 8 or 10 inches of soil. 



The Shoot. — The growth habit varies from the spreading vine 

 type through forms that are semi-erect to erect. (Fig. 190.) In 

 decumbent forms, there are relatively few short branches which 

 attain a length of 2. to i3^ feet and a diameter of approximately 

 an inch at the base. In large erect types, the main stems are very 

 thick, reaching a diameter of an inch and half, and the branches, 

 which range from 10 to 17 in number, may be 6 feet in length. The 

 branching is usually sympodial so that the successive principal axes 

 are developed from axillary buds and the terminal buds produce 

 inflorescences or abortive branches. (Fig. i9i.) Each axillary 

 bud continues the vegetative shoot, producing leaves at several 

 nodes, and then terminates in an inflorescence. This mode of 

 development may be repeated many times until the axis is several 



