The inflorescence is a pseudo-umbel subtended by two large deciduous bracts at the apex of a long, erect scape, up to 2 m (6.6 ft) tall.

Some hybrids and cultivars have colors not found in wild plants which includes bi-colored blue/lavender and white flowers flushed with pink as the blooms mature.

[citation needed] The genus Agapanthus was established by Charles Louis L'Héritier de Brutelle in 1788.

In the Cronquist system, the genus was placed in a very broadly defined family Liliaceae, along with other lilioid monocots.

In 1996, following a phylogenetic analysis of DNA sequences of the gene rbcL, Themidaceae was resurrected and Agapanthus was removed from Alliaceae.

This was not accepted by the Angiosperm Phylogeny Group when they published the original APG system in 1998, because the clade consisting of Agapanthus and Amaryllidaceae had only 63% bootstrap support.

[12] The table below summarizes the alternative family divisions: Further molecular phylogenetic analyses of DNA sequences have confirmed that Agapanthus is sister to a clade consisting of subfamilies Allioideae and Amaryllidoideae of the family Amaryllidaceae (sensu APG III).

[15] Four additional species had earlier been recognised by Leighton (1965) (A. comptonii, A. dyeri, A. nutans and A. walshii),[16] but were given subspecific rank by Zonneveld and Duncan.

In New Zealand, Agapanthus praecox is classed as an "environmental weed"[53] and calls to have it added to the National Pest Plant Accord have encountered opposition from gardeners.

As a rule, Agapanthus species are pest-hardy, neither being much attacked nor drastically affected by common garden pests.

The larvae of the moth bore into the budding inflorescence and as they mature they tunnel down towards the roots, or emerge from the stem and drop down to feed on the leaves or rhizomes.

[54] In 2016, a new species of gall midge, Enigmadiplosis agapanthi, was described damaging Agapanthus in the United Kingdom.