The Araceae are a family of in which are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe (or leaf-like bract). Also known as the arum family, members are often colloquially known as aroids. This family of 114 genera and about 3,750 known species
Description
Within the Araceae, species are often
rhizomatous or
; many are
Epiphyte, creeping
Liana or
Vine plants, and the
Leaf and tissues of the entire plant nearly always contains irritating
calcium oxalate crystals or
, in varying degrees.
The foliage can vary considerably from species to species. The majority of species produce an
inflorescence consisting of a spadix (which some compare to a
Corncob, in appearance), which is nearly always surrounded by a modified leaf bract called a
spathe.
In
monoecious aroids, possessing separate male and female flowers (but with both flowers present on one plant), the spadix is usually organized with female flowers towards the bottom and male flowers at the top. In aroids with
, the stigma is no longer receptive when the
pollen is released, thus preventing self-
fertilization. Some species are
dioecious.
Many plants in this family are thermogenic (heat-producing).
File:044 Dracunculus vulgaris at Akrotiri peninsula, Crete, Greece.jpg|Snake lily, Dracunculus vulgaris, in Crete
File:Xanthosoma sagittifolium at Kadavoor.jpg|Arrowleaf elephant ear, Xanthosoma sagittifolium
File:Amorphophallus titanum (corpse flower) - 2.jpg|Corpse flower, Amorphophallus titanum, 2 or 3 metres tall
Toxicity
Within the Araceae family, the majority of species produce calcium oxalate crystals in the form of
Raphide. While it is possible to consume the cooked foliage of certain genera, such as
Alocasia,
Colocasia, and
Xanthosoma, as well as the ripened fruits of
Monstera deliciosa, these raphide compounds are irritating (and even dangerous) for many animals, including humans. Consumption of raw aroid vegetation may cause
edema, vesicle formation or
dysphagia, accompanied by a painful stinging and burning in the mouth and throat, with symptoms occurring for up to two weeks, depending on amount consumed. In smaller amounts, patients report feeling a mild to extreme sensation of sand or glass in the esophagus and mouth, lasting up to 48 hours.
Additionally, in heavier instances of ingestion,
Anaphylaxis could cause swelling of the throat, restricting breathing. The genus
Dieffenbachia is famously known as "dumb-cane" for this reason; however, given the presence of irritating compounds across the family, this nickname may be applied to virtually any genera within the Araceae.
Taxonomy
Phylogeny
Phylogeny based on the Angiosperm Phylogeny Website.
Classification
One of the earliest observations of species in the Araceae was conducted by
Theophrastus in his work
Enquiry into Plants.
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 in his book
Familles des Plantes.
The first major system of classification for the family was produced by Heinrich Wilhelm Schott, who published Genera Aroidearum in 1858 and Prodromus Systematis Aroidearum in 1860. Schott's system was based on floral characteristics, and used a narrow conception of a genus. Adolf Engler produced a classification in 1876, which was steadily refined up to 1920. His system is significantly different from Schott's, being based more on vegetative characters and anatomy. The two systems were to some extent rivals, with Engler's having more adherents before the advent of molecular phylogenetics brought new approaches.
A comprehensive taxonomy of Araceae was published by Mayo et al. in 1997.
Modern studies based on gene sequences show the Araceae (including the Lemnoideae, duckweeds) to be monophyletic, and the first diverging group within the Alismatales.[ pp. 830–834.] However Lemna and its allies were incorporated in Araceae in the 2019 edition.
Genera
143 genera are accepted within the Araceae.
[ Araceae Juss. Plants of the World Online. Retrieved 28 April 2024.] Anthurium,
Epipremnum,
Monstera,
Philodendron and
Zantedeschia are some of the most well-known genera of the family, as are the
Colocasia (taro,
arbi) and
Xanthosoma ('elephant-ear', ‘ape), which are both cultivated for human consumption. The largest unbranched inflorescence in the world is that of the arum
Amorphophallus titanum (titan arum).
The Araceae includes many ornamental genera of global economic importance: Aglaonema, Alocasia, Anthurium, Caladium, Dieffenbachia, Epipremnum, Homalomena, Monstera, Nephthytis, Rhaphidophora, Scindapsus, Spathiphyllum, Syngonium, and Zamioculcas, to name but a few. The aquatic genera Anubias, Bucephalandra and Cryptocoryne are highly prized and cultivated aquarium plants; other, recently-described genera, such as the Lagenandra of India, are gradually becoming more known in the aquascaping world.
Fossil record
The family Araceae has one of the oldest
fossil record among
angiosperms, with fossil forms first appearing during the
Early Cretaceous epoch.
[Sender, L.M., Doyle, J.A., Upchurch, J.R. Jr., Villanueva-Amadoz, U. and Diez J.B. 2019. Leaf and inflorescence evidence for near-basal Araceae and an unexpected diversity of other monocots from the late Early Cretaceous of Spain. Journal of Systematic Palaeontology, vol. 17, p. 1093–1126.][Nauheimer, L., Metzler, D. and Renner, S.S. 2012. Global history of the ancient monocot family Araceae inferred with models accounting for past continental positions and previous ranges based on fossils. New Phytologist, vol. 195, p. 938-950.] Notable fossils from the Early Cretaceous include:
Spixiarum kipea,
[Coiffard, C., Mohr, B.A.R. and Bernardes de Oliveira, M.E.C. 2013. The Early Cretaceous aroid, Spixiarum kipea gen. et sp. nov., and implications on early dispersal and ecology of basal monocots. Taxon, vol. 62. p. 997-1008.] an aroid from the late
Aptian of Brazil;
, an aroid leaf from the late
Albian of Spain;
and
Turolospadix bogneri, an aroid spadix from the late Albian of Spain.
Food plants
Food plants in the family Araceae include
Amorphophallus paeoniifolius (elephant foot yam),
Colocasia esculenta (kochu, taro, dasheen),
Xanthosoma (cocoyam, tannia),
Typhonium trilobatum and
Monstera deliciosa (Mexican breadfruit). While the aroids are little traded, and overlooked by plant breeders to the extent that the Crop Trust calls them "orphan crops", they are widely grown and are important in subsistence agriculture and in local markets. The main food product is the
corm, which is high in
starch; leaves and flowers also find culinary use.
See also
-
List of foliage plant diseases (Araceae)
Further reading
-
Bown, Deni (2000). Aroids: Plants of the Arum Family ILLUSTRATED. Timber Press.
-
online
External links
