Discovering Botanical Families: An Introduction

Have you ever noticed that some of the plants you grow have similar characteristics? That some of the flowers on the perennials in your flowerbeds and some of the fruit on the annuals in your vegetable garden have similar characteristics? These observable similarities are not a figment of your imagination; they’re very real and demonstrate an obvious link between certain plants. These familiar links enable botanists to classify plants into botanical families. Yes, plants have families!

The similarities between the fruits of vegetable garden plants: here, squash, cucumber and melon plants all belong to the same family, the Cucurbitaceae.

What Is a Botanical Family?

A botanical family is a grouping of plants that share common genes and traits because they come from the same parent. While these traits often include similarities in flower and fruit structure, they can also include similarities in leaf, stem and even seed structure. Some families even have specific adaptations to their environment, such as the Cactaceae (cactus family).

The Example of the Rosaceae Family

To illustrate this family classification, let’s take the example of plants in the Rosaceae family. They generally share a similar floral organization, with petals in multiples of 5 and a large number of stamens. Their vegetative apparatus also shares common morphological traits, as evidenced by their leaves, which are always alternate and often stipulate.

These characteristics bear witness to their evolutionary kinship and their membership of the same botanical family. Of course, other factors are studied by specialists and taken into account to definitively establish their filial link. So, more than one criterion is needed to identify a family. For example, not all flowers with 5 petals are Rosaceae.

In the hierarchy of botanical classification, the family lies between the order (broader) and the genus (more specific). It generally encompasses several genera, and the latter, several species. A plant therefore usually has a genus and a species, and sometimes even a variety. All this under the aegis of the binomial nomenclature established by Linnaeus, which stipulates, among other things, the exclusive use of Latin. Just a moment, please, a little popularization.

The Plant Classification System

Without going into too much scientific detail, where it would be all too easy to get lost, let’s see how a plant can be classified. Here we propose the spearmint (genus Mentha and species spicata) belonging to the Lamiaceae family. In the table below, you’ll see that mint has several cousins such as monarda, sage, thyme and lavender, all plants in the Lamiaceae family.

With a heritage of almost 400,000 plant species, this classification system helps taxonomists, botanists, biologists and other scientists worldwide to organize plant diversity, understand evolutionary relationships between species and facilitate identification, all in a common language. For the horticulturist, it offers the possibility of better understanding certain needs common to plants in the same family, a particularly useful asset when planning crop rotations in the vegetable garden.

We’re passionate about teaching botany, so we thought we’d take you on a fun journey through botanical families over the next few articles. We have selected families of horticultural interest that are being studied as part of the horticulture and gardening program at the vocational training level.

Here are some families of horticultural interest that we propose: Solanaceae, Cucurbitaceae, Bromeliaceae, Cactaceae, Orchidaceae, Brassicaceae, Lamiaceae, Asteraceae, Araceae and many others!

See you soon!