Species of Synchytrium in Louisiana. VI. Two New Species on Impatiens and Smilax

The galls are found on stems, petioles and leaves of Impatiens pallida Nutt. and I. biflora Walt. They are most abundant at base of plant, often closely crowded and sometimes one on another (fig. 1). They occur on any part of the stem but are usually most abundant just below the nodes, especially near the base of the plant. When abundant they cause swellings of the infected parts and a dwarfing of the plants. They are few and scattered on petioles and leaves. The infections occur on small, young plants growing in low lands that are flooded for short periods in the late winter or early spring. The zoospores penetrate the epidermal cells when very young and before there is any differentiation into palisade and mesophyll tissues. The galls are variable in size and shape. Those on the stems range from hemispherical to elongated. Those on the leaves and petioles are usually smaller than those on the stems and those on the leaves are mostly on the under surface and spherical or nearly spherical. They are composed mostly of very loose meso? phyll tissue. Those on the stems range from 320 X 400 to 560 X 960 fi. Those on the leaves range from 480 X 480 to 700 X 800 /x. They vary from green to pink and are composed of parenchyma tissue. The epidermal cells are small. The cavities in the galls vary in size and shape. They are formed by the enlargement of the infected epidermal cells which become covered by growths of the surrounding cells. The opening to the cavity (infected cell) closes but is distinct (fig. 3). The cavity may become spherical