The tomato is a warm-season crop, sensitive to frost but reasonably resistant to heat and drought, thriving under a wide range of climate and soil. A frost free season of seventy-five to ninety days will mature home garden tomatoes in useful quantities if good plants are set but over 120 days are needed for economical commercial production. Plant growing requires six to eight weeks previous to setting out-of-doors. Each fruit requires about six weeks from blossom to ripeness. The fruit ripens best for yield, color and quality when the weather is warm and sunny. Low temperatures without frost are not favorable for growth and prolonged conditions of this sort may "check" the plant and retard the response when higher temperatures come. The tomato is sensitive to extreme day-length, setting fruit at 7 to 19 hours but not at 5 or 24 hours.[2] The tomato responds readily to fertilizers and to moisture, coming quickly into vigorous growth after unfavorable conditions, unless too badly stunted. As long as moisture and nutrients are available and other conditions are favorable, a tomato plant will continue to branch and blossom and make fruit almost indefinitely. A pruned single stem plant in a greenhouse at Cornell once reached a length of over 40 feet during a year and a half of growth. Thus, it is really a herbaceous perennial grown in northern climates as an annual. The plant branches freely at leaf joints but fruit clusters are formed along the bare stem,--a habit not common among plants. Some varieties are "determinate" in habit, sometimes miscalled "self-pruning," as branches only attain limited length. [Illustration: FIGURE 2.--The tomato flower. Varieties differ in protrusion of pistil beyond the stamen column. If style is too short, pollination may fail; also, if too long. A long pistil increases danger of damage from heat and drying out.] Hot, dry winds often damage floral parts and the blossoms drop without setting fruit. Smith[3] has shown that pollen grains germinate best at 85° F., almost as well at 70° F., poorly at 50° F. and very poorly at 100° F. [Illustration: FIGURE 3.--Long section of tomato flower.] The flowers of the tomato are borne in simple racemes or, in some varieties, in compound clusters. The flowers are normally on the plan of 5 but cultivated varieties may have six or eight sepals and petals. Sepals are narrow and may be as much as an inch long. Petals are united at the base. Stamens are united by the anthers surrounding the style and stigma. The ovary or little tomato is above the calyx but, as it grows, it carries corolla and stamens outward until they, with stigma and style, drop off. Length of style is a fairly important character in its bearing on pollination and on susceptibility to heat and wind injury. Seedless Fruits