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Water Milfoil Family. Comprised of 8 genera and 145 species of land, marsh, and water herbs with small leaves and small flower clusters. Flowers are usually unisexual, wind-pollinated, with three- to four- chambered ovary and a similar number of styles.

Entry link: Haloragaceae


The dense inner part of a tree trunk, yielding the hardest timber.
Entry link: Heartwood


Referring to a plant, with the stems dying back to the ground at the end of the season.
Entry link: Herbaceous


Organism that is being attacked by a parasite or a parasitoid.
Entry link: Host


Mud Snail Family. Comprised of over 260 species of very small, freshwater and brackish water snails with an operculum. Members of this family have a shell height of less than 8mm, are dextrally-coiled and smooth.

Entry link: Hydrobiidae


Frog's-bit or Tape-grass Family. Comprised of 18 genera and about 135 species of submerged and emergent freshwater and saltwater aquatic herbs. They are generally dioecious and produce radially symmetrical flowers.

Entry link: Hydrocharitaceae


Waterleaf Family. A small family with about 250 species that are annual or perennial herbs or shrubs. Most are grown as ornamentals. Members of this family usually have blue or purple flowers, hairy leaves without stipules, and seed capsule containing many seeds.
Entry link: Hydrophyllaceae


Leaf Snail Family. Small to medium-sized air-breathing land snails, terrestrial pulmonate gastropod mollusks.

Entry link: Hygromiidae