On the same slope, and on no other, I go about the 1st of May for lupine, or sun-dial, which makes the ground look blue from a little distance; on the other, or northern side of the slope, the arbutus, during the first half of April, perfumes the wild-wood air. A few paces farther on, in the bottom of a little spring run, the mandrake shades the ground with its miniature umbrellas. It begins to push its green finger-points up through the ground by the 1st of April, but is not in bloom till the 1st of May. It has a single white, wax-like flower, with a sweet, sickish odor, growing immediately beneath its broad leafy top. By the same run grow water-cresses and two kinds of anemones,--the Pennsylvania and the grove anemone. The bloodroot is very common at the foot of almost every warm slope in the Rock Creek woods, and, where the wind has tucked it up well with the coverlid of dry leaves, makes its appearance almost as soon as the liverwort. It is singular how little warmth is necessary to encourage these earlier flowers to put forth! It would seem as if some influence must come on in advance underground and get things ready, so that when the outside temperature is propitious, they at once venture out. I have found the bloodroot when it was still freezing two or three nights in the week; and have known at least three varieties of early flowers to be buried in eight inches of snow. Another abundant flower in the Rock Creek region is the spring beauty. Like most others it grows in streaks. A few paces from where your attention is monopolized by violets or arbutus, it is arrested by the claytonia, growing in such profusion that it is impossible to set the foot down without crushing the flowers. Only the forenoon walker sees them in all their beauty, as later in the day their eyes are closed, and their pretty heads drooped in slumber. In only one locality do I find the ladies'-slipper,--a yellow variety. The flowers that overleap all bounds in this section are the houstonias. By the 1st of April they are very noticeable in warm, damp places along the borders of the woods and in half-cleared fields, but by May these localities are clouded with them. They become visible from the highway across wide fields, and look like little puffs of smoke clinging close to the ground. On the 1st of May I go to the Rock Creek or Piny Branch region to hear the wood-thrush. I always find him by this date leisurely chanting his lofty strain; other thrushes are seen now also, or even earlier, as Wilson's, the olive-backed, the hermit,--the two latter silent, but the former musical.