June is the month with the most daylight. The longest day of the year is June 24, the day of John the Baptist, the light-bringer in the Bible. One of the most popular medicinal plants, St. John’s Wort (Hypericum perforatum)—used in Weleda medicines, has a special connection to light and sun. Its flowers’ yellow color, the receiving attitude of its branches, the arrangement of its leaves so none is in shadow, and the way the cells hold the oil, visible in the petals and leaves as little points — the whole plant is like stored sunlight. With these characteristics, the plant can bring light to people who suffer from dark moods and depressions. In the...