Araceae

The Araceae are a household of monocotyledonous flowering plants where blossoms are borne on a form of inflorescence called a spadix. The spadix is usually accompanied by, and at times partially enclosed, a spathe or leaf-like bract. Also referred to as the arum family, members are often colloquially called aroids. This family of about 3750 species that are known and 114 genera is temperate areas and most diverse although distributed in the Old World tropics.

Among the largest collections of living Araceae is preserved in the Missouri Botanical Gardens.

Description

Species from the Araceae are often rhizomatous or tuberous and are often found to contain calcium oxalate crystals or raphides. The leaves may vary from species to species. The inflorescence is made up of a spadix, which is almost always surrounded by a modified leaf called a spathe. In monoecious Aroids (owning separate male and female flowers, but with both flowers present on a single plant), the spadix is generally organized with female flowers towards the bottom and male flowers towards the top. In aroids with perfect flowers, the blot is no longer receptive once the pollen is released, thus preventing self-fertilization. Some species are dioecious.

Many plants in this family are thermogenic (heat-producing). Their flowers can reach up to 45 if the air temperature is lower. 1 reason for this unusually significant fever is to attract insects (usually beetles) to pollinate the plant, rewarding the beetles with heating energy. Another reason is to avoid tissue damage. A few examples of thermogenic Araceae include Symplocarpus foetidus (eastern skunk cabbage), Amorphophallus titanum (titan arum), Amorphophallus paeoniifolius (elephant foot yam), Helicodiceros muscivorus (dead horse arum lily), and Sauromatum venosum (voodoo lily). Species such as the horse arum and titan arum give off an odour to attract flies to pollinate the plant. The heat can help to convey the scent.

Classification

Among the earliest observations of species at the Araceae was conducted by Theophrastus in his job Enquiry into Plants. The Araceae wasn’t recognized before the 16th century as a distinct group of plants. In 1789, Antoine Laurent de Jussieu categorized all climbing aroids as Pothos and all terrestrial aroids as Arum or Dracontium in his book Familles des Plantes.

The first big method of classification for the household was made by Heinrich Wilhelm Schott, who printed Genera Aroidearum in 1858 and Prodromus Systematis Aroidearum in 1860. Schott’s system used conception of a genus, and was based on characteristics. Adolf Engler Produced a classification. His system is different from Schott’s, being based on human anatomy and characters. Both systems were to some extent competitions, with Engler’s having more adherents before the arrival of molecular phylogenetics introduced new approaches.

Modern studies based on gene sequences reveal the Araceae (such as the Lemnoideae, duckweeds) to be monophyletic, and the first diverging group within the Alismatales. The APG III system of 2009 admits the household, including the genera formerly segregated from the Lemnaceae. The sinking of the Lemnaceae to the Araceae is not accepted. For Instance, the 2010 New Flora of the British Isles utilizes a paraphyletic Araceae plus another Lemnaceae. A thorough genomic analysis of Spirodela polyrhiza was printed in February 2014.

Genera

Anthurium and Zantedeschia are two renowned members of the household, as are Colocasia esculenta (taro) and Xanthosoma roseum (elephant ear or’ape). The largest unbranched inflorescence in the world is that of the arum Amorphophallus titanum (titan arum). The family includes many ornamental plants: Dieffenbachia, Aglaonema, Caladium, Nephthytis, and Epipremnum, to name a few. The genera Cryptocoryne, Anubias and Bucephalandra are lots of popular aquarium plants. Philodendron is an important plant in the ecosystems of this rainforests and is commonly utilized in home and interior decorating. Symplocarpus foetidus (skunk cabbage) is a standard eastern North American species. An interesting peculiarity is that this family contains the largest unbranched inflorescence, that of the titan arum, often erroneously called the”largest flower” and the smallest flowering plant and smallest fruit, located in the duckweed, Wolffia.

Fossil record

The family Araceae has among the earliest fossil record among angiosperms, with fossil forms first appearing during the Early Cretaceous epoch. Notable fossils from the Early Cretaceous contain Spixiarum kipea, an aroid in the late Aptian of Brazil; Orontiophyllum ferreri, an aroid leaf from the late Albian of Spain; and Turolospadix bogneri, an aroid spadix in the late Albian of Spain.

Toxicity

Within the Araceae, genera like Alocasia, Arisaema, Caladium, Colocasia, Dieffenbachia, and Philodendron contain calcium oxalate crystals in the form of raphides. When consumed, these can lead to edema, vesicle formation, and dysphagia accompanied by painful burning and stinging to the throat and mouth, with symptoms occurring for up to fourteen days following ingestion.

Food plants

Food plants in the family Araceae comprise Amorphophallus paeoniifolius (elephant foot yam), Colocasia esculenta (kochu, taro, dasheen), Xanthosoma (cocoyam, tannia), Typhonium trilobatum and Monstera deliciosa (Mexican breadfruit). While the aroids are traded, and Overlooked by plant breeders that the Crop Trust calls These”orphan crops”, they are widely grown and are significant in subsistence agriculture and local markets. The principal food product is the corm, which is high in starch; leaves and flowers also find culinary usage.