. The botany of crop plants : a text and reference book. Botany, Economic. ii6 BOTANY OF CROP PLANTS where cold or wet weather prevents flower opening. In India, it has been observed that cross-pollination in wheat is more frequent than in northern climates. In the wild wheat of Palestine, the kernels are normally retained by the spikelet. It differs also from domesticated wheat in the order of maturity of the spikelets. In do- mesticated wheat, the first spikelets to de- velop flowers are those near the middle of the head, while in the primitive wheat the terminal spikelets are the first ones
. The botany of crop plants : a text and reference book. Botany, Economic. ii6 BOTANY OF CROP PLANTS where cold or wet weather prevents flower opening. In India, it has been observed that cross-pollination in wheat is more frequent than in northern climates. In the wild wheat of Palestine, the kernels are normally retained by the spikelet. It differs also from domesticated wheat in the order of maturity of the spikelets. In do- mesticated wheat, the first spikelets to de- velop flowers are those near the middle of the head, while in the primitive wheat the terminal spikelets are the first ones. Primi- tive wheat also shows some indications of sexual dimorphism. Some plants have been observed to bear protogynous, others pro- tandrous, flowers. The spikelets of this wild form never mature more than two grains (Fig. 41), and those of the same spikelet are unequal in size. The smaller grain is borne by the lower flower in the spikelet; this flower has the longer awn too. A. Schulz thinks that many, but not all, of the primi- tive wheat individuals found by Aaronsohn are hybrids between T. agilopoides ihaoudar and dicoccoides. The origin of the different types of cultivated wheats, as given by Schulz, is shown in the following: 1. Einkorn series, of which T. tegilopoides is the prototype. 2. Emmer series, of which T. dicoccoides is the stem form. From this have come dicoccum, durum, turgidum, and polonicum. 3. Spell series, of which the stem form is unknown. From this have come spella, compactum, asliimm, and capUatumi. Fig. 41.—Spike- let of wild emmer (Triticum dicoc- cum dicoccoides). Enviromnental Relations.—Wheat is grown under a wide range of temperature conditions. Some varieties come to maturity and yield well as far as 64° N. latitude in Norway,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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