Dahlia

Dahlia sp. · Garden flowers

Dahlia

Brooklyn Botanic Garden, 26 July 2025

A dark-leaved red dahlia in the summer border.

Dahlias are native to Mexico and Central America, where they grow at high elevation as tuberous perennials, and the Aztecs grew them for food as much as ornament. Almost every garden dahlia descends from a handful of wild species crossed and re-crossed since the plant reached Europe in the 1790s, which is why named cultivars run into the thousands and a species name doesn't really apply.

Dahlia, quilled

Brooklyn Botanic Garden, 29 May 2025

Petals rolled into loose quills, magenta-pink around a tight orange centre still holding unopened disc florets - one of the many dahlia forms bred for petal shape rather than colour. The Aztecs grew dahlias for the tubers, which are edible and taste of very little, and the hollow stems of one species were used as water pipes; the flower was an afterthought until the Spanish sent it to Madrid in 1789.

Dahlia, palest pink

Brooklyn Botanic Garden, 21 July 2024

A fully double dahlia, the disc florets almost hidden under rank after rank of petals, each one edged in a thin line of red that the plain pink centre doesn't carry. Dahlias are octoploids, carrying eight sets of chromosomes where most plants have two, which is why they cross and vary so freely and why there are tens of thousands of named varieties from a handful of Mexican species.

Dahlia

Brooklyn Botanic Garden, 21 July 2024

A single-form dahlia, magenta shading to white at the base of each petal around an open ring of golden disc florets - the un-doubled flower still showing the daisy-family structure that heavy breeding buries in the fuller cultivars.

Singles like this are the ones bees can use. A fully double dahlia has bred its pollen and nectar out of reach, and a border of them is a border insects fly straight past.