in Thoreau’s Journal:
Now is the season of the leafing of the trees & of planting. The fields are white with houstonias, as they will soon be yellow with buttercups.
Perchance the beginning of summer may be dated from the fully formed leaves––when dense shade? begins––I will see. High blue berries at length. It is unnecessary to speak of them. All flowers are beautiful. The salix alba is about out of bloom. Pads begin to appear though the river is high over the meadows. A caterpillar’s nest on a wild cherry. Some apple trees in blossom— Most are just ready to burst forth—the leaves being half-formed. I find the fever bush in bloom but apparently its blossoms are now stale. I must observe it next year. They were fresh perhaps a week ago. Currants in bloom by Conants spring—are they natives of America? A ladies slipper well budded & now white.
The v. ovata is of a deep purple blue—is smooth &––pale blue delicately tinged with purple reflections.–– the cucullata is more decidedly blue slaty blue & darkly stained.
The white violets by the spring are rather scarce now. The red oak leaves are very pretty & finely cut about 1 3/4 inches long. Like most young leaves they are turned back around the twig parasol like. The farmers apprehend frosts these nights. A purplish gnaphallium with 3 nerved leaves.