What are the largest plant families?

The climate, the land, the location,… all these are factors that shape the evolution of each of the plants, because what every living being wants is precisely to continue existing. Thanks to this, the survival instinct makes the plant kingdom what it is today: a spectacle in itself, one that humans have the opportunity to enjoy.

What are botanical families?

Before getting into the subject, I would first like to explain what a family is in botany, since in this way if you are curious to know which are the most numerous families of plants, you will know exactly how important they are. Well, there are some 400,000 accepted plant species in the world, not counting varieties or cultivars (if so, that number would surely be close to a million… or it may even exceed it).

As humans, one of our characteristics is that we like to classify things, since this makes it much easier for us to learn about them. That is why the experts, in this case the botanists, what they do is group the plants that are as similar as possible, not only in appearance, but also in terms of their evolution and, therefore, also their genetics.

Taking all this into account, today we know, for example, that although Cycas and palm trees are quite similar, in reality they are not related. While the former are considered living fossils since they began to evolve more than 300 million years ago, palm trees are more ‘modern’ plants since their evolution began about 140 million years ago.

But that’s not all: Cycas are gymnosperm plants, that is, they are plants that do not protect their seeds in a fruit (be it capsule, legume, or etc.), but rather those reddish balls that we see are the seeds; palms, on the other hand, are angiosperms, that is, they protect them in a fruit that is usually fleshy, such as dates.

As you can see, identifying plants is much more than looking at their appearance. For all this, at present more than 100 botanical families have been established.

What are the most numerous plant families that exist?

Now that we know that it is a botanical family, we have to talk about the most numerous. There are many that are very big, but without a doubt the ones that deserve to be in the top 5 are the following:

Asteraceae (compound plants)

Image – Flickr/ jacinta lluch valero// Aster tataricus

It is the most numerous by far. It contains about 32,913 species divided into about 1911 genera. These are normally herbaceous plants, although they can be trees, shrubs or climbers. They can be annual, biennial or perennial. The leaves are alternate and spiral generally greenish.

The flowers are small, hermaphroditic, or rarely unisexual or sterile, and are grouped in inflorescences composed of chapters. The fruits are cyselas, that is, the seed is attached to numerous very light hairs that will help it move away from the mother plant.

In this botanical family we find the Aster, Senecio, or the Helichrysum, among others.

Orchidaceae (orchids)

Image – Wikimedia/ sunoochi from Sapporo, Hokkaido, Japan// Phalaenopsis hygrochila

Orchids are in second place, something that lovers of these plants may like. It is estimated that there are about 25,000 species (some say that there are about 30,000) divided into 800 genera. They are herbaceous, perennial or annual plants, with a terrestrial or epiphytic habit, or sometimes climbing plants. In the case of terrestrial ones, the stems are rhizomes or corms, whereas in epiphytes the leaves thicken at the base, forming pseudobulbs.

The leaves are simple, often alternate, spiral, distal or whorled, with or without petioles. The flowers are one of the most complex in the plant kingdom, even in certain species of orchids they take on animal shapes, with very bright colors. The fruits are berries that contain the seeds.

Examples of this family we have Phalaenopsis, Cattleya, or Dendrobium, among others.

Fabaceae (legumes)

Image – Wikimedia/ Felix Vieira// Caesalpinia pulcherrima

This is a family that also has great economic importance, not only because many produce edible seeds, but there are also many with great ornamental value. In it we find 19,400 species distributed in some 730 kinds of herbs (annual, biennial or perennial), trees, shrubs and climbers. The leaves are generally alternate, perennial or deciduous, pinnate or bipinnate, green in color.

Its flowers can be small or large, composed of five brightly colored petals, and they are grouped in cluster-like inflorescences. The fruits are more or less long legumes that contain seeds that are often blackish and leathery.

Examples of legumes are, for example, Delonix regia ( flamboyant ), Acacia, Caesalpinia or Vicia sativa ( peas ).

Poaceae (grasses)

Image – Wikimedia/ Citron/ CC-BY-SA-3.0// Phyllostachys viridiglaucescens

They are the fourth most numerous family, with some 12,100 described species spread over more than 820 genera. Despite being the fourth, it is the first in terms of economic importance, since a large part of them we feed ourselves… and many farm and poultry animals, as well as some domestic ones.

In general we speak of herbs, woody, tussock, rhizomatous or stoloniferous, which can be annual, biennial or perennial depending on the species. The stems are cylindrical to elliptical, with hollow or solid internodes (like corn), and from them sprout long alternate green leaves. The flowers are grouped in spikelet-shaped inflorescences, and are unisexual or hermaphroditic. The fruits are small and dry.

Examples of grasses include Triticum ( wheat ), Oryza sativa or Oryza glaberrima ( rice ), Zea mays ( corn ), Hordeum vulgare (barley), the subfamily Bambusoideae ( bamboo ) or Avena.


Image – Wikimedia/ Alpsdake// Gardenia jasminoides

And last but not least, we are going to talk to you about the Rubiaceae. This family comprises more than 10,000 species divided into about 600 genera, and they are trees, shrubs, herbs, or climbers, generally of a terrestrial habit although there are some that are epiphytes. The leaves are opposite, whorled or rarely pinnatifid, perennial or sometimes deciduous.

The flowers are grouped in terminal inflorescences, and are actinomorphic or rarely zygomorphic. The fruits are simple or multiple, and can be drupes or capsules, and contain the seeds.

Examples of plants that belong to this family are the Gardenia, the Galium, or the Bouvardia.

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