M OST plant starch consists of two major components, amylopectin and amylose. Both are a-glucosides, but amylopectin has a branched-chain molecule, while amylose has an essentially straight-chain structure. Nielsen and Gleason (12) reported about 20% amylose in the starch of a number of vegetables (including smooth peas) but found 75% amylose in the starch of wrinkled peas. Hilbert and MacMasters (6) studied wrinkled-pea starch further and found an amylose content of 60 to 70% in the starch of the three wrinkled varieties, Alderman, Perfection, and Stratagem, while Peat, Bourne, and Nicholls (13) reported as much as 98o/o amylose in the starch of Steadfast peas.Several other investigators have reported in personal correspondence that they also had found high amylose content in wrinkled-pea starch but not in smooth-pea starch. Wrinkled peas contained only about 35% total starch compared with 45% in smooth peas. If peas are to have commercial value as a source of amylose, they should contain as high a percentage of starch as possible, as well as a high amylose content of the starch. A study of the inheritance of starch and amylose in peas appeared desirable.Mendel (11) found the inheritance of seed form (smooth or wrinkled) in peas to be due to a single gene pair, Rr) with smooth dominant to wrinkled. This explanation is still accepted today. It would be of interest to both the plant breeder and the geneticist to know whether Rr also governs the difference in (a) starch content and (b) amylose content of the starch which has been found between smooth and wrinkled peas to date. If the factor does, then it would appear impossible to breed a smooth-seeded, high-starch-content pea, with high amylose content of the starch. The purpose of this paper is to present some data obtained on this subject.Several investigators in the early part of the century noted that starch grains from smooth and wrinkled peas differed in appearance. Gregory (5) (as reported by Reichert,14) found that the starch grains in nine varieties of peas he examined were simple, oval, and regular in shape, whereas the grain in seven varieties of wrinkled peas were compound and showed a strong tendency to break up into smaller parts. Darbishire (3) also reported differences in the starch grains of smooth and wrinkled peas. He found F 1 cotyledons to have starch grains intermediate in appearance between the smooth and wrinkled parents, although the majority were simple like the smooth parent. Kappert (7) did not think the starch grains from wrinkled peas were compound but were simple grains provided with splits. He thought the split type was almost completely dominant in F 1 cotyledons, but that the form of the grain was intermediate to the two parents.Reichert (14) found simple, oval starch grains in 16 varieties of smooth peas and compound grains in eight varieties of wrinkled peas which he examined. Maige (9) studied the development of the starch grains in smooth and wrinkled peas and also noted only simple grains in the smooth peas and compound grai...

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