This section is from the "The Herb Hunters Guide" book, by A. F. Sievers. Also available from Amazon: Herb Hunters Guide.

Figure 24.Blue vervain (Verbena hastata)
Verbain, false verbain, wild hyssop, simpler's-joy, ironweed.
Vervain is found in moist fields, meadows, and waste places from Nova Scotia to British Columbia and Florida, Nebraska, and Arizona.
This rather rough, finely haired herb has an erect, straight 4-sided stem, 4 to 7 feet high, usually branched above with broadly lance-shaped sharply toothed leaves. The small, usually blue, flowers are densely clustered in numerous slender panicled spikes 2 to 6 inches long.
The herb.
 
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