Transverse Vein Research Articles

Water Pathways in Wheat Leaves. I. The Division of Fluxes Between Different Vein Types

This study concerns the pathway of water movement through the vascular system of the wheat leaf blades. These water pathways were followed using three kinds of markers dissolved in the transpiration stream by which the patterns of water reticulation were made visible. There was a partitioning of the total water flux between the veins of the different types. The lateral veins dominate the conduction of water along the leaf from the base, and also distribute water to the mesophyll in their immediate vicinity. The intermediate veins receive water from the lateral veins in the transverse direction, via the transverse veins. The intermediate veins are primarily involved in the distribution of water to the mesophyll in their vicinity. Since there are more intermediate veins than lateral veins across the leaf blade they are the more important distributors of water to the mesophyll. The transverse veins are the pathway by which water is moved transversely from the lateral veins to the intermediate veins. Water can also be conducted in both directions, or in either direction, from its point of entry into an intermediate vein from a transverse vein. This versatility enables the network of transverse and intermediate veins to act as alternative pathways for longitudinal water conduction in the event of damage to a lateral vein.

Loading of Assimilates in Wheat Leaves. I. The Specialization of Vein Types for Separate Activities

An autoradiographic study is reported of the movement of labelled assimilate into the vein network in the area of the leaf fed 14CO2, and in the zone of the leaf proximal to the fed area. In the fed area the labelled assimilate is concentrated first in the intermediate veins and transported via the transverse veins to the lateral veins in which it rapidly moves basipetally. The intermediate veins distribute the label up and down the leaf 1-2 mm to or from the nearest transverse vein. They appear to function primarily as loading, collecting and distributing reservoirs. Proximal to the fed zone, the labelled assimilate translocated in the lateral veins spreads into the network of transverse and intermediate veins. The vein types have therefore different primary functions and may differ in their transport mechanisms. Measurements of the cross-sectional area of phloem in the three types of veins along the leaf blade are consistent with the idea that the laterals are translocating veins and the intermediates are collecting reservoirs. Quantitative estimates are made of the fluxes of assimilate in the three vein types.

NOTES ON SCIOMYZIDAE WITH DESCRIPTIONS OF NEW SPECIES

Tetanocera clara Lw. Mass., Conn. Specimens of this species with typical frontal markings, have the posterior transverse vein nearly straight and perpendicular, as in valida. In a single specimen there is an incomplete brownish-black abdominal stripe, interrupted at the incisures.

MICRO-LEPIDOPTERA

This genus approaches Gelechia, but not so nearly as Anarsia, Parasia,&c., the hind wings being sublanceclate, and not emarginate beneath the apex, and having a different neuration. Dr. Clemens describes four species. only one of which, H. chalcofrontella, is known to me. Gelechia glandulella, Riley, belongs here. The genus is divisible into two branches.A. In which the median vein of the hind wings gives off one branch before the transverse vein and a furcate branch behind it, and the curved apical branch.