And from the day on which you bring the sheaf [omer] of elevation offering the day after the holiday you shall count off seven weeks. They must be complete: you must count until the day after the seventh week fifty days; then you shall bring an offering of new grain to the Lord.
Once the first sheaves of the barley harvest were brought to the priest as an offering on the second day of Pesach, seven weeks were counted off (what has become known as the counting of the omer during which time, apparently, the barley harvest was completed as the wheat ripened. The fiftieth day was the festival of Shavuot, at which an offering of leavened bread was to be made, baked from the new grain. This was the beginning of the wheat harvest, and this bread represented an initial offering, first fruits of that harvest: You shall observe the feast of Shavuot, of the first fruits of the wheat harvest [Exodus 34:22].
Wheat, it seems, represented prosperity and stability, and served as a symbol for abundance of food in biblical poetry [Deuteronomy 32:14; Psalm 81:17; Psalm 147:14]. In the Bible, fine bread and fine flour are always made from wheat.
In the Mishnah (Pesachim 2:5), five types of grain are specified as being suitable for making into matzah and, it follows, susceptible to becoming chameitz (technically, the term chameitz refers only to foods made of these five grains; the Ashkenazic custom of avoiding legumes and rice and corn on Pesach is a somewhat mysterious custom of medieval origin, but is not based on a definition of rice, corn, and legumes as actual chameitz.) As is often the case, the exact botanical definitions of the five grains are open to some debate, but it seems that they are: barley, oats (which has never been a major crop here), and three different species of wheat. Similarly, only bread made from these five grains is covered by the blessing hamotzi lechem min haaretz, and requires the full Birkat HaMazon.
Aaron Aaronsohn, son of farmers from the First Aliyah in Zichron Yaakov, studied agronomy in France and returned to engage in research on the genetics of the native varieties of wheat. In 1906 he discovered strains thought to be among the most primitive in the world, containing the basic gene pool from which later domesticated varieties developed. (Aaronsohn went on to found the Nili spy ring, which supplied strategic information on the Turks to the British during the First World War; his sister Sarah was captured and tortured by the Turks in 1917, and committed suicide in captivity.)
Recently we joined our daughter on a field trip with her economic botany class at Ben Gurion University, and visited the wheat research center at Tel Aviv University, where we saw cold rooms holding thousands of samples of wheat seeds, some of them taken from local wild varieties that have already become extinct in nature. This genetic treasure has already been exploited to develop, through scientific cross breeding, varieties resistant to newly emerging viruses and other pests. Thus, while Israel must import a significant portion of its wheat, it exports wheat genes and expertise - even to Iowa.
[What was] the tree from which Adam ate? Rabbi Judah says: it was wheat, for a baby isnt able to say Daddy and Mommy until he is old enough to eat cereal (i.e., wheat is the source of knowledge of right and wrong)
-Babylonian Talmud, Sanhedrin 70b
Perhaps, in view of the central nutritional and economic status of wheat, and its role as a symbol of stable, cultivated, abundance here in Eretz Yisrael, this midrash is not so far-fetched.