Common St. Johnâ€™s-Wort (Klamath Weed)
Shrublike, much branched, perennial herb, with sometimes woody stem bases, and leafy shoots. Flowers many, yellow, in flat or domed inflorescences. Petals 5, broad at base, with relatively few black dots, usually at or near the margins; sepals with or without a few yellowish-brown to black dots. Blooms Mayâ€“September. Leaves many, crowded, opposite; each pair is at right angles with those above and below (decussate), with many translucent spots; sessile, linear to oblong, to 1Â˝ inches long.
Similar species: There are 14 species of Hypericum recorded for Missouri. Some of the most common are these natives: shrubby SJW (H. prolificum), St. Andrewâ€™s cross (H. hypericoides), nits-and-lice (H. drummondii), pineweed (H. gentianoides), dwarf SJW (H. mutilum), spotted SJW (H. punctatum), and round-fruited SJW (H. sphaerocarpum).