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Here is an overview of five common families of flowering plants. The list includes two of the top three families – the Asteraceae (Aster family) and the Fabaceae (Legume family) – but does not include the Orchidaceae (Orchid family). We’ll look at orchids later – they deserve a session entirely to themselves. The families included here, and the approximate number of species they represent, are:

1. Acanthaceae (Acanthus family) – 2,500 species
2. Asteraceae (Aster family) – 23,000 species
3. Fabaceae (Legume family) – 19,400 species
4. Rubiaceae (Coffee family) – 10,000 species
5. Verbenaceae (Verbena family) – 2,000 species

Add up these numbers and you’ll see that these 5 families represent more than 57,000 species of flowering plants, so the chances are good that you’ll be able to find representatives of each of these families no matter where you live.

To make the best use of this information, be sure you know the 19 Basic Botanical Terms and are using the Plant Profile Sheet when studying plants. Then study this page, paying particular attention to the Identification tips for each family. Finally, print out this article for use in the assignment found in Start Learning Plants.

[Note: all images on this page are in the public domain via wikimedia commons.]

Acanthaceae (Acanthus family)

Description: “This is a family that includes several genera of plants with tubular flowers designed to be pollinated by hummingbirds, butterflies, and moths, all of which can reach the nectar with their long bills or proboscii” (kingsnake). Mostly tropical herbs or shrubs comprising about 250 genera and 2,500 species. Species known to temperate gardeners include Bear’s breeches (Acanthus mollis) and tropical genera known to temperate gardeners include Thunbergia and Justicia (wikipedia.)

Identification: Herbs, shrubs, or twining vines. Leaves are simple and opposite with each pair being at right angles to the pair below. Without stipules. The leaves may contain calcium carbonate concretions seen as streaks on the surface. (wikipedia)

Examples: Species known to temperate gardeners include Bear’s breeches (Acanthus mollis) and tropical genera known to temperate gardeners include Thunbergia (black-eyed susan vine) and Justicia (red shrimp plant).

Asteraceae (Aster, Daisy, or Sunflower family)

Description: The Asteraceae is the second largest family of dicots, with some 1,100 genera and over 20,000 recognized species. Only the orchid family (Orchidaceae) is larger, with about 25,000 described species (wikipedia). Members of this Cosmopolitan group are characterized by the structure of their inflorescences. In most cases, an asteracean “flower” is actually a multitude of tiny flowers placed together in a “head” (”capitula”) surrounded by whorls of petal-like bracts….Some asteraceans, like the sunflower and lettuce, have great economic importance as crops (kingsnake).

Identification: Most species occur in open, dry environments. The most common characteristic of these plants is an inflorescence or flower head; a densely packed cluster of many small, individual flowers, usually called florets (meaning “small flowers”). Leaves can be alternate, opposite, or whorled. They may be simple, but are often deeply lobed. The margins can be smooth or toothed. (wikipedia).

Examples: daisy, dandelions, lettuce

Fabaceae (Legume family)

Description: The legumes form the third largest family of plants (after Orchidaceae and Asteraceae) with more than 19,000 species described to date (wikipedia). They can be herbs, shrubs, lianas, or trees, and are characterized mainly by the kind of fruit they produce. When mature, this is usually a dry, elongated capsule containing from one to many seeds.

The family is divided into three subfamilies, mainly distinguished among themselves by the structure of their flowers.

Subfamily Caesalpinioideae – 2,000 species

The flowers are bilaterally symmetrical, and in such way can be divided into halves only along one plane.

Subfamily Mimosoideae – 3,200 species

The flowers are radially symmetrical, like a star, in such a way that they can be dissected along any vertical plane passing through their centers to form two identical halves. Some species in this group are peculiar for being sensitive to mechanical disturbance. When touched, their leaves will immediately close along the central stem.

Subfamily Papilionoideae – 14,000 species

(Click on the labeled image of a Wisteria, above, to see the details better.) In this subfamily the petals are fused together. The adaxial (superior-posterior) exterior of the lateral petals (wings) forms with the two anterior-inferior petals (keel) a strongly zygomorphic corolla. The result is that many of this flowers look remarkably like orchids. This is the group that contains those species with the greatest economic importance to man: the beans and peas so widely cultivated around the World (kingsnake).

Identification: Alternate, compound leaves. Produce pods.

Examples: redbuds (Caesalpiniodeae), mimosa (Mimosoideae), pea (Papillionoideae)

Rubiaceae (Coffee family)

Description: The Rubiaceae are variously called madder, bedstraw, or coffee family. There are about 600 genera and more than 10,000 species in the family (wikipedia). Coffee is an infusion of the grounded seeds of Coffea arabica and a few related species. Most members of the family produce fruits in the form of berries, often brightly colored (kingsnake).

Identification: Entire, opposite leaves; interpetiolar stipules.

Examples: coffee, ixora, gardenia, partridgeberry.

Verbenaceae (Verbena family)

Description: The Verbenaceae or Verbena family is a family of mainly tropical plants notable for heads, spikes, or clusters of small flowers. The family includes about 90 genera and nearly 2,000 species of trees, shrubs and herbs (wikipedia). The Verbena family includes the genus Lantana, a garden favorite related to oregano (with the same odor in their leaves). Wild Lantana are common mainly in dry forests and in clearings (kingsnake).

Identification: Opposite or whorled leaves, usually simple. Leaves aromatic, stems sharply tetragonal.

Examples: Lantana, oregano