Haloragidaceae (Water-milfoil) -- Family is made up of perennial herbs, creeping or sprawling, with erect branched tips. The stems often root at the nodes that are partially submerged.

The leaves are alternate on the stem. The leaves are either finely divided or serrate-toothed.

The flowers are small, symmetrical in form and bisexual in nature. There will be three sepals that persist at the top of the ovary, no petals, three stamens. Flowers are usually solitary in the upper leaf axils.

Fruit is small, three-angled or oval, splitting into three nutlets at maturity.

Hamamelidaceae (Witch Hazel) -- Family is made up of shrubs and trees with small flowers in head-like or spike-like clusters.

Witch-Hazel Hamamelis virginiana

The flowers are radially or bilaterally symmetrical; bisexual or unisexual in nature; with a tubular base bearing four to five sepals and four to five petals. Stamens number four to many. The ovary is embedded in the base (inferior ovary). The leaves are usually alternate on the stem, simple or palmately lobed and often toothed. Fruit is a woody capsule. There are some 23 genera worldwide and about 100 species found in subtropical and warm temperate regions of North America, Asia and South Africa.

The various family memebers are often used as ornamental landscape plants.

Hippocastanaceae (Horsechestnut) -- This family is made up of trees and shrubs. There are some 15 genera in temperate regions and mountains of tropical America. Six native tree species in North America are in the Buckeye genus.

Red Buckeye Aesculus pavia

The flowers are many and showy in large upright branched clusters. The clustered flowers are often large and irregular, slightly bell-shaped. Both male and female flowers are on the same tree (bisexual). The calyx is tubular-shaped. Both calyx and corolla are made up of four or five generally unequal petals. The colors may be red, yellow, pink or white. There are six to eight long curved stamens and one pistil composed of a three-celled ovary with two ovules in each cell. The style is long and curved. Fruit is a large rounded brown capsule, often spiny with a hard thick wall.

The leaves are deciduous (evergreen in the tropics), opposite on the stem, long stalked, palmately compound with five to nine elliptical or lance-shaped leaflets. Most leaves are saw-toothed; stipules absent.

Hydrangeaceae (Hydrangea) -- This family of plants is made up of deciduous, soft-woody shrubs and vines, having stout branches with thin flaky bark.

Oak-leaf Hydrangea Hydrangea quercifolia

The preferred habitat is shady to semi-shady environments, on moist slopes, and in bottomland forests, along ravenes and streams. The seeds are spread primarily through bird droppings. The leaves consist of one whole part, occasionally lobed, often whorled. The leaf stalks are long.simple, opposite on the stem. The flowers are bisexual and unisexual on the same plant. Bisexual flowers have a five-lobed calyx and five white petals. The fertile flowers are usually clustered. The sterile flowers have three to four white or colored sepals. The ovary is inferior; eight to ten stamens.

Fruit is capsule.

Hydrophyllaceae (Waterleaf) -- These plants are usually herbs (rarely shrubs) that are often bristly or glandular, with flowers usually arranged along one side of the branchs or at the tip of a stem in coils like fiddlenecks.

Each flower is radially symmetrical in form with united sepals. There are five united petals that vary from nearly flat to bell-shaped; five stamens that protrude from the corolla. All these parts are attached at the base of the ovary (ovary superior).

The leaves are simple (one whole part), pinnately compound and alternate on the stem (sometimes opposite) or in basal rosettes.

Fruit is a capsule.

There are about 20 genera and over 275 species existing nearly worldwide.. The western United States is the main center of diversity.

Hypericaceae (St. Johnswort) -- The family is made up of leafy herbs or shrubs, usually with yellow or orange flowers in branched clusters.

Dwarf St. Johnswort Hypericum mutilum

The flowers are radially symmetrical with five separated sepals, five petals that are usually separated and numerous stamens that may be united into bundles. All these parts are attached at the base of the ovary (ovary superior). The leaves are simple and opposite or whorled about the stem, often with black or translucent dots. Fruit is a berry or capsule. There are about eight genera and some 400 species distributed in temperate and tropical regions. Many are grown as ornamental garden plants.