H. vulgaris

H. vulgaris may refer to:
 * Hippuris vulgaris, the common mare's tail, a common aquatic plant species found in Eurasia
 * Hydra vulgaris, a small freshwater hydroid species
 * Hydrocotyle vulgaris, the marsh pennywort, a small creeping perennial herb species native to North Africa, Europe, Florida and west to the Caspian region