Seed coats [of Brassica and Sinapis species] under the scanning electron microscope

Scanning Electron Microscope photographs of seed coats of Brassica and Sinapis species, at 500 magnifications, clearly show the characters of seed coats. Identical seed coats of various intraspecific entities within Brassica campestris (weed seed, rapeseed, turnip, Chinese cabbage and Tori) emphasize the futility of trying to separate many intraspecific entities by means of seed coats characters. However, the SEM photographs show the distinct differences present on the seed coats of Brassica campestris L., B. napus L., B. oleracea L., B. nigra (L.) Koch, B. juncea (L.) Czern., Sinapis alba L. and S. arvensis L. The amphidiploid B. napus (2n = 38, genome aacc) clearly combines the seed coat characters of its diploid ancestors B. oleracea (2n = 18, genome cc) and B. campetris (2n = 20, genome aa). Even more dramatically, the amphidiploid B. juncea (2n = 36, genome aabb) combines the seed characters of the ancestral diploids B. campestris (2n = 20, genome aa) and B. nigra (2n = 16, genome bb).