838 XXX. AEOIDE^E. 



Most Aroidecp are tropical, and especially abound in the large American forests and in the temperate 

 regions of the Andes. Tropical Asia possesses fewer, but this is there compensated by the elegance and 

 variety of the species. Few are met with north of the tropic of Cancer. Orontiaceec and CnUacea; are 

 the most arctic; one (Calla palitstris) extends in North Europe to 64. The true Arums are principally 

 met with in the east of the Mediterranean region. The number of Aroideai hitherto observed in Africa is 

 not considerable ; the United States of America possess at most six species. Symplocarpus grows in 

 North Asia and America, as well as Arctiodi'amn, which extends beyond 49. Richardia belongs to 

 South Africa; Cryptocorynea: are met with in the swamps of Asia and on the sandy hills of tropical 

 Africa ; Aristema inhabits the mountains of sub-equatorial Asia and North America. Acorus is a native 

 of North Asia, and has been introduced into Europe. GymnostacJiys grows in east and extra-tropical 

 Australia. Pistia is common in the waters of the whole tropical zone. 



The spadix of several Arums gives off when in flower more or less heat. This phenomenon, 

 observed by Lamarck, Bory, Hubert, Brongniart, Van Beck, &c., is especially remarkable in tropical 

 species ; the maximum of heat developed by our Arum maculatum is 7 to 9 above that of the surrounding 

 air; but Colocaxia cordifotia and odora emit a heat more than 10, 12, and even 22 above that of the 

 atmosphere, according to Van Beck and Bergsma. 



Some Aroidea; exhale during flowering a repulsive odour ; as, amongst others, Dracunctdm crinitus, 

 the cadaverous exhalations from which attract flies, which descend to the bottom of the spathe, where 

 they are entangled in the long hairs ; but if some species are foetid, others on the contrary are sweet- 

 scented, as Richardia eefJiiopicfi, of South Africa, cultivated in Europe for the beauty and perfume of its 

 white spathe, which encloses a golden spadix. Many Colocasias and Caladiums are now cultivated in 

 our hothouses and public gardens on account of the elegance and size of their leaves. 



Aroidea; are remarkable for the abundance of crystals throughout their tissue. Delile has discovered 

 them even in the anthers, where they are mixed with the pollen-grains. 



The rhizome and leaves of Arvide.a contain a very acrid juice, which may occasion serious accidents ; 

 Layenandra toxicaria, quoted by Lindley, is considered a most violent poison ; the stem and leaves of 

 Dii-ffrnbachia Scguina produce, when chewed, a violent inflammation of the mucous membrane, and a 

 swelling of the tongue which renders it impossible to speak; the leaves of Colocasia and of Arum are also 

 extremely irritating, but this acridity is removed by desiccation or cooking, and almost entirely disappears 

 at the flowering season. This acrid principle accompanies, in the rhizome, an abundance of starch, useful 

 as food. 



Arum maculatum, a European plant, was prescribed by the ancienta as an excitant in affections of 

 the mucous membrane ; it was also applied externally as a rubefacient and epipastic ; but its qualities 

 vary so much with the age of the plant that it has fallen into disuse. Calla palustris was formerly classed 

 among alexipharmics, on account of its violent diaphoretic properties. Many other Aroidea: are used aa 

 medicinal plants, such as, among the genera of the Mediterranean region, Arum, Aritarum, Dracunculus, 

 and Biarum. The principal species renowned in Indian medicine nre : Amorphophallus campamdatus, 

 Typhonium trilobatum, Arisatma triphyllum, pentaphyttum, Dracontinm, Scindapsus ojficinalis, &c. The root 

 of Symplocarpus foctidus, remarkable for its foetid odour, resembling that of the polecat, is much 

 employed by the Americans against asthma and chronic coughs. The dried root of Orontium aquaticum 

 is considered edible in the United States. The leaves of Monstera pertusa, full of raphides, are slightly 

 caustic, and are used, bruised, as a topic, for anasarca in tropical America. 



Those Aroidea! which have starchy and edible rhizomes principally belong to the section Colocasiea. 

 The most celebrated is Colocasia antiquorum, a native of India, cultivated in Egypt from time immemorial, 

 and spread all over the tropics. C. himalaiensis 1 supports, with Arisama utile, the inhabitants of the 

 Indian mountains. Other congeneric species are cultivated in Bengal. The Taro (Alocasia macrorrhiza) 

 abounds in the Pacific Islands. The rhizome and fructiferous spadix of Peltandra virginica, of North 

 America, are equally edible. The fleshy spadices, bearing perfumed and well-tasted fruits, of Tornelia 

 frin/rans (Monstera deliciosa) are habitually sold in Mexican markets, where they rival the Pine-apple in 

 estimation. The shoots of Xanthosoma sagUta-folium, known under the name of Caraibe Cabbage, are 



1 Probably C. antiquorum, or Alocasia indica, is here referred to. The Himalayan Arisaemas are only resorted 

 to in times of scarcity. ED. 



