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Transvaal specimens of Cosmarium decoratumW. & G.S. West var. decoratum, C. decoratumvar. galpiniiClaassen and C. striolatum(Näg.) Arch. var. nordstedtii(Möb.) W. Krieg. were examined with a light microscope and a scanning electron microscope. The cell wall ornamentation of C. decoratumvar. decoratumand C. striolatumvar. nordstedtiiis discussed and compared with descriptions and illustrations found in the literature. The cell wall ornamentation of C. decoratumvar. galpiniiis compared with that of C. decoratumvar. decoratum.The name combination C. striolatumvar. nordstedtiiproposed by Krieger (1932) is applied and the name C. glyptodermumis placed in synonymy.

Corn was grown in large buried containers and stressed nonrepetitively by cessation of irrigation at nine different times during the season. Each stress treatment consisted of 4 days on which the uppermost, fully‐expanded leaves were wilted. Water status of the yield plants was estimated in terms of the relative turgidity (RT) of like‐treated plants, soil moisture and other environmental factors. Vegetative component yields were determined in two experiments, the first including the additional factor of limiting soil fertility. Each component was significantly influenced by one or more of the stress periods. Maximum reductions in total vegetative dry matter production of 15 to 17% resulted from water deficits approximately 3 weeks before 75% silking. Significant increases in stalk weight occurred as a result of stress at late silking and very early ear stages.

Under controlled irrigation, corn plants grown in large containers were subjected to water deficits in one of nine periods during each of two growing seasons. The first experiment (1965) differed from the second (1966) by somewhat different timing of treatments and by limiting soil fertility conditions. A significant grain yield reduction (12 to 15%) was observed after stress during the vegetative period at early ear shoot and ovule development in 1966. A 53% grain yield reduction was associated with stress at 75% silking in 1965. In the 3‐week period after silking, water deficits consistently reduced yields approximately 30% in both years. Significant reductions in kernel numbers were associated with yield reductions from stress before or during silking and pollination. Kernel weights were significantly reduced by stress during or after silking. Trends in the percentage of developed kernels in each of three ear sections indicated that the ability of kernels to compete for products of photosynthesis correlated with the comparative age of the ovule or kernel at the time of water deficit.