Leaf Vascular Bundles Research Articles

The cytochemical localization of nucleotide pyrophosphatase activity in plant tissues using naphthyl esters of thymidine-5'-phosphate.

A cytochemical method for the localization of nucleotide pyrophosphatase activity in plants employing naphthol AS-BI thymidine 5'-monophosphate and alpha-naphthyl thymidine 5'-monophosphate as specific substrates is reported. Biochemical evidence for the validity of this method is presented and the synthesis of the naphthol AS-BI ester is described. The application of this cytochemical technique to shoots of Triticum sp. and roots of Vicia faba has shown nucleotide pyrophosphatase to be ubiquitous in its distribution in these organs and to occur in a structurally-bound form in the cytoplasm. The highest activity was detected in developing fibres adjacent to the leaf vascular bundles, in the coleoptile epidermal and hypodermal cells and in the coleoptile and leaf xylem.

Interveinal Distance for Carbohydrate Transport in Leaves of C3 and C4 Grasses1

Among common crop and range Gramineae, we found that species with the C4 pathway for photosynthesis had fewer cells between leaf vascular bundles than did C3 species. We extracted chlorophyll from leaf segments of 10 Ca and 10 C4 species, cleared the segments in 10% aqueous NaOH, counted the number of mesophyll cells between vascular bundle sheaths, and measured the distance (center to center) between the vascular bundles. The C3 species had 9 to 15 mesophyll cells between vascular bundle sheaths, while the C4 species had only 2. The vascular bundles were 0.18 to 0.36 mm (average 0.27) apart in C3 species, but only 0.08 to 0.15 mm (average 0.11) apart in C3 species. The closeness of all leaf cells to vascular tissue in C4 species suggests efficiency for transporting the products of photosynthesis and may be an important factor in their greater capacity to fix CO2.

The Coal-Age Flora of Kansas. III. Psaronius cooksonii a New Species Showing Caulopteris Features

1. A well-preserved silicified specimen of the genus Psaronius, showing both the internal anatomy and the external features of Caulopteris, is described (as P. cooksonii) from the Kansas Wabaunsee group, Upper Pennsylvanian. 2. Anatomically, it is characterized by twelve foliar bundles alternating with twelve peripheral bundles. The leaf scars are in twelve vertical rows arranged in alternating whorls of six leaves each. Evidence is presented to show that the pattern of the leaf trace scar varies (depending on the distance from the base of the petiole) from a straight band to a U-shape, then to an oval-shape, and finally to an oval with an inclosed inverted V. It is also pointed out that when the Caulopteris surface is free from the usual sheath of adventitious roots, the leaf vascular bundle scar is visible only as a slightly curved band within the base of the protruding petiole scar, its higher configurations being simulated by the fissure between inner parenchyma and outer sclerotic zones of the petiole.