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Greenhouse, growth chamber, and laboratory studies were conducted to determine anatomical and morphological characteristics and cultural practices limiting the distribution of cogongrass, torpedograss, and johnsongrass in the United States. Cogongrass did not produce axillary buds along most of the rhizome nor regenerate when apical six-node-long rhizome segments were buried deeper than 8 cm. Both torpedograss and johnsongrass produced axillary buds along the entire lengths of their rhizomes. Torpedograss shoot emergence decreased at burial depths between 8 and 16 cm. Shoot emergence from johnsongrass rhizomes was not affected by burial as deep as 16 cm. Rhizomes of all three species were tolerant of desiccation. Cogongrass grew better in soil at pH 4.7 than in soil at pH 6.7, whereas torpedograss and johnsongrass grew equally well in either pH. It is postulated that cogongrass spread is limited by lack of axillary bud formation on most of the rhizome and the inability of rhizomes to send up new shoots if buried deeper than 8 cm. These factors could account for the intolerance of cogongrass to cultivation. Torpedograss appears to spread only vegetatively due to the lack of viable seed production.

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A bstract. Isolated Phaseolus mitochondria will swell spontaneously in buffered KCI and contract with an oxidizable substrate or ATP +-Mg2'. The conditions under which the mitochondria are swollen affect subsequent contraction, substrate oxidation and ion accumulation, but not their oxidative phosphorylation ability. Bovine serum albutmin reduces the rate of swelling and promotes substrate oxidation, contraction and ion accumulation. Swelling of these mi-tochondria is associated with the release of malic dehydrogenase and a loss of membrane integrity. The beneficial effects of bovine serum albumin in preserving the energy linked functions of Phaseolus mitochondria is discussed.Volui.me changes of isolated animal mitochondria have been extensively studied (6, 17) but there has been relatively little work with plant m.itochondria.Investigations thave been carr.ied ouit on the rela--tionship between imitochondrial swelling aind the chiilling sensibivity of plant tissues (21) and the effects of ethylene on volume changes of cautliflower miLtochondria (20). The most detailed information so far on plant mitochondrial swelling and contraction has come from the studies of Hanson and his associates using preparations from etiol'ated corn shoots ( 13,14,16,33,34 With -the exception of calcium binding, which we have not -investigated, all of 'these phenomena are exhibited by Phaseolus mitochondria. In other words, the -mechanism of swelling and contraction wotlld appear to be 'similar to the situation in corn.In the experiments repo-rted here we have set out to investigate the effec;t of swelling on various metabolic functions of the mitochondria. We have been particutlarly interested throughout in attempting -to ascertain what features, in addition to X -I level might be influtencing the con-traction process. Materials and Methods

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