Carolina Nightshade, Horse-nettle, Devil's Tomato, Solanum carolinense. No matter the name, this is one poisonous plant. And no matter the danger, this is one beautiful little plant. This species first came up in Spring where I mistakenly thought this to be a vine. It must be the way it was intertwined in a fence row.
From A Manual of Weeds:A near relative of the potato and one of the worst weeds native to this country; southern in its origin but rapidly making its way northward and westward through the agencies of impure clover seed and baled hay. The deep-seated rootstocks are most tenacious of life; an Indiana farmer states that they " will live ten years under a heap of sawdust and grow as soon as the dust is removed." Sheep are the only grazing animals that will touch the plant, and they merely nibble off the fruits; the seeds are widely scattered in their droppings and many a productive acre is thus practically ruined.
The fruit will ripen to a yellow color and can last on the plant throughout the winter.
Georgia, Ada Eljiva. A Manual of Weeds. New York, 1919. 365-6. Web. Google Book Search. 31 Jul 2009.