How do people know that these ingredients are recipes of Fake blood? (Spoiler)

The fable story is as follows:
Once there was a knight who, though upright and noble-looking, had a prickly, unapproachable appearance.
He fell in love with a fragile young maid, whom he saw with her sisters in a field, all wearing bright red wimples.
But he was afraid his prickly exterior would frighten her, so he asked the advice of another knight, a pious and learned crusader, who carried the name of the patron saint of his order with pride.
The pious knight told him he would arrange a rendezvous with the maid, all three would drink wine together by the river and he would help his friend to get acquainted with her.
This they did, but the maid fell in love instead with the pious knight. The stern knight was enraged and challenged his rival to a duel. The two fought long and fiercely, but they were equally matched, and so in the end they both fell, mortally wounded.
Their bodies lay together on the ground, and the blood flowed from them into the river, turning the waters crimson.
Anguished at the tragedy her beauty had caused, the young maid took a dagger from one of the knights and plunged it into her own heart.

I can guess that Wine is from the fable story. Because they drink in the fable story.
I can guess St. John’s wort from the fable story. Because the Crusaders are in the fable story.
Poppy is red, which I can understand, but I can’t figure out how it is hidden in this fable.
Even Thistle, I can’t understand how it is hidden in this fable.
Can anyone explain those?

Thistle - knight who, though upright and noble-looking, had a prickly, unapproachable appearance.
Poppy - fragile young maid, whom he saw with her sisters in a field, all wearing bright red wimples.
St. John’s wort - another knight, a pious and learned crusader, who carried the name of the patron saint of his order with pride.
Wine - all three would drink wine together by the river

Thank you very much for your reply, which makes it easier for me to remember it. :slight_smile: