Widow's Cross, Glade Stonecrop (Sedum pulchellum)

Low winter annual, 2-12" tall, usually spreading at the base; grows on exposed limestone. Leaves: alternate, linear, round in cross-section, to 1.5" long, anthers often red, flowers are crowded on 3-7 short, divergent branches, each 1-3" long. 

Bloom time: April - May. Where found: limestone ledges, roadsides, and openings, from KY and GA, west to OK and TX. Characteristic plant of the cedar glades of middle TN but also occurs on cliffs; is currently spreading along TN roads in limestone gravel. Frequent.

Note: The name "Widow's Cross" comes from the shape of the 4-petaled flower. Stonecrops generally prefer the arid climates of deserts, rocky shores, tundra, and other dry, open areas because heir fleshy leaves store water. 

The pores on the leaves conserve water by opening at night to admit carbon dioxide, which is needed for growing, and closing during the heat of the day to prevent water loss.