Plants, Betonica officinalis or B. alopecuros, of the Labiate order, having spiked purple flowers and ovate crenate leaves. In former days medicinal and magical virtues were attributed to them. Except for Vervain, no plant was more esteemed by old-time herbalists than Betony, whence the Italian proverb, "Sell your coat and buy Betony." From Vettones, an ancient people inhabiting the Ibernian peninsula.
The Vettones in Spain discovered the plant called vettonica in Gaul, serratula ("the plant with leaves like a saw") in Italy, and cestros or psychotrophon by the Greeks, a plant more highly valued than any other. It springs up with an angular stem of two cubits, spreading out from the root leaves rather like those of lapathum, serrated, and with a purple fruiting-head.

Pliny 25.46.84

This wort, which is named betony, is produced in meadows, and on clean downlands, and in shady places; it is good whether for the man's soul or for his body: it shields him against monstrous nocturnal visitors and against frightful visions and dreams; and the wort is very wholesome... If a man's head be broken, take the same wort betony, scrape it then and rub it very small to dust, then take by two drachms weight, and swallow it in hot beer.

Apuleius1.1

Oinos Kesrites [Betony wine] And a wine is made of that Betony, which they call Psychotrophon.

Dioscorides 5.54

Sisumbrion [Stachys germanica]. Sisymbrium, somme call it Serpillum sylvestre, somme Veneris corona, the Latines Austeralis, others Herba Venera, growes in untillowed groundes.¥

Dioscorides 4.2

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Bettonike [Lythrum Salicaria?] Britannica or Vettonica is an herb having leaves like to Lapathum sylvestre, but blacker, & more hairy, binding in the taste... [Betonie grows in meadows, & hilly & clean and mild places, about the shrubs.]¥

Dioscorides, 2.155

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Betony groweth up with long leaves and broad, of a darke greene colour, slightly indented about the edges like a saw.¥

Gerard 2.106

¥Whether it applies to Betonica officinalis (the most reputed in the ancient pharmacopeia), or B alopecuros, as Sainean claims; betony has crenate leaves, while the leaves of hemp are toothed. (Crenate - having the edge notched or toothed with rounded teeth, finely scalloped.)