Commelinaceae is a family of plants, commonly called the dayflower family, spiderwort family, or tradescantia family. It’s in the order Commelinales, which belongs to the clade of monocotyledons. In total it contains between 600 and 800 species (depending on which botanists you ask), in about forty genera.
Plants in the family are mostly perennials, or sometimes annuals. Most grow in the ground, but there is one genus of epiphytes and a few climbers. They generally have a scrambling growth habit and root easily at the nodes.
The most distinctive feature of their foliage is that each leaf attaches to the stem with a sheath which wraps all the way around. Leaves are always simple and smooth-edged, with no lobes or teeth. They are often somewhat succulent, storing water in their stems and leaves.
Inflorescences mostly emerge from the tips of new growth, and sometimes from lower branches. Their flowers have three petals, but sometimes one of the petals is much smaller or a different shape from the other two. Each individual flower is very short-lived, closing within a few hours (hence the name “dayflower”).
This site focuses on cultivated plants of the Commelinaceae family – so this is an incomplete list of only the commonly-grown genera. Click the links for more detail about the species in each genus (work in progress!).
Commelinaceae are native in different climates all over the world, so they can also be cultivated in many different ways.
Tropical species from the warmest places can be grown permanently outdoors only in similar climates. In temperate locations (like the UK and much of North American and Europe) they can be grown outdoors as summer annuals, or – perhaps most often – as houseplants all year round.
Hardy temperate species can generally only be grown in climates similar to their native range. They’re used as garden perennials, dying back to the roots in winter and flowering in summer.
And there are of course some species which blur the lines between tropical and hardy, and can be successfully grown indoors or outdoors in mild temperate climates.
If you’re growing tropical Commelinaceae foliage plants indoors, you can read a care guide here.