Plant · P-306

Field Horsetail

Equisetum arvense

Field Horsetail's wiry, silica-rich stems steep into a classic organic fungicide tea, useful against mildew and other fungal disease in a humid climate. Its rhizomes run six feet deep - deeper than almost anything else - mining minerals other plants cannot reach, but that same silica makes the living plant unpalatable, and it must never end up in cut hay: drying does not destroy the toxin that strips B vitamins from grazing animals, and horses are especially vulnerable. It needs permanently damp ground to persist, but wherever it gets that wet toe of soil, it holds the spot indefinitely with no further input.