Araceae
A family of flowering plants with spadix inflorescences and often toxic sap.
Wikipedia / Wikimedia Commons
The Araceae, also known as the arum family or aroids, are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix, usually accompanied by a spathe. This family of 114 genera and about 3,750 known species is most diverse in the New World tropics, although also distributed in the Old World tropics and northern temperate regions. Many species are rhizomatous or tuberous, and the leaves and tissues nearly always contain irritating calcium oxalate crystals.
- Oldest fossil
- Spixiarum from the Late Cretaceous (the previously cited Mayoa portugallica is a possible aroid but not definitively the oldest)
Lore & Background
The Araceae were not recognized as a distinct group of plants until the 16th century. In 1789, Antoine Laurent de Jussieu classified all climbing aroids as Pothos and all terrestrial aroids as either Arum or Dracontium. The first major system of classification was produced by Heinrich Wilhelm Schott, who published Genera Aroidearum in 1858 and Prodromus Systematis Aroidearum in 1860, based on floral characteristics. Adolf Engler produced a classification in 1876, based more on vegetative characters and anatomy, which was steadily refined up to 1920. The two systems were to some extent rivals, with Engler's having more adherents before the advent of molecular phylogenetics.
Reader's Guide
The Araceae are significant for their ecological and economic roles. Many species are thermogenic, producing heat to attract pollinators such as beetles and flies, and some emit a pungent smell akin to rotten meat to attract flies. The family includes both the largest unbranched inflorescence (titan arum) and the smallest flowering plant (Wolffia duckweed). Food plants include Colocasia esculenta (taro), Xanthosoma (cocoyam), and Monstera deliciosa, though raw consumption can cause painful irritation due to calcium oxalate crystals. The family has one of the oldest fossil records among angiosperms, with forms appearing during the Early Cretaceous. Modern studies show the Araceae (including duckweeds) to be monophyletic and the first diverging group within the Alismatales, though the inclusion of Lemnaceae was not immediately universally accepted.
Did You Know?
- The family includes the largest unbranched inflorescence in the world, that of Amorphophallus titanum (titan arum).
- Many aroids are thermogenic, with flowers reaching up to 45 °C to attract pollinators.
- The genus Dieffenbachia is famously known as 'dumb-cane' due to irritating calcium oxalate crystals.
- The oldest confirmed aroid fossil is Spixiarum from the Late Cretaceous; the previously cited Mayoa portugallica is a possible aroid but not definitively the oldest.
Frequently Asked Questions
Who is Araceae?
Araceae is a family of monocot flowering plants—commonly called aroids or the arum family—that encompasses roughly 3,750 species across 114 genera. They are most diverse in the New World tropics, though they also appear in Old World tropical regions and northern temperate zones.
What are Araceae's signature traits?
Every member bears its flowers on a spadix inflorescence, almost always wrapped by a modified bract called a spathe. Nearly all species also pack their leaves and tissues with irritating calcium oxalate crystals, making their sap a notorious contact irritant.
When does Araceae's story begin?
The oldest known fossil linked to the family is Mayoa portugallica, which dates to the Early Cretaceous. That pushes the family's origins back to a period when dinosaurs still roamed the Earth.
Why is Araceae important in the plant world?
As one of the most species-rich monocot lineages, the family anchors tropical understory ecosystems through its rhizomatous and tuberous growth habits. Genera like Monstera, Philodendron, Anthurium, and Colocasia also make it a cornerstone of global horticulture and indoor plant culture.
What is Araceae's most legendary feat?
The titan arum (Amorphophallus titanum) produces the largest unbranched inflorescence of any known plant, a towering structure infamous for its overwhelming rotting-flesh odor. It remains the family's most spectacular and widely photographed bloom.
More in Flowering Plant Families 1-21
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