Aroidee. | THE HIMALAYAN MOUNTAINS. | 405 
things an observant people, have, like Linneus, seen the affinity of Pistia to Lemna, 
though the correct anatomy of these plants was known to neither ; they call the former 
pana, and the latter noonya pana, or small pana. Pistia Stratiotes is found flourishing 
in the rainy season in every part of India, that is, from the Peninsula to the neighbour- 
hood of Saharunpore, and is also said to occur in the West Indies. 
Lemna, found in ditches and ponds in the cooler parts of the world, occurs also in 
similar situations in the cold weather months, both in the southern and northern parts of 
India. Three or four species have been described by Dr. Roxburgh ; more will probably 
be found, and require a careful comparison with European specimens to ascertain their 
identity or difference. 
189. AROIDEA. 
The Aroidea, named from the genus Arum, consisted until lately of onlyea few 
other genera, as Caladium, Calla, Dracontium, Orontium,-and a few others, which have 
now been removed to different families. Schott having submitted the whole of the 
well-known species to careful revision, has, in the Meletemata Botanica, divided the 
old into a number of new genera, of which the names are adopted in this work. The 
Aroidee, distinguished by having their flowers on a spadix, and supported by a spathe, 
have occasionally united with them, the genus Acorus, which has the scaly rudiments 
of a perianth, as well as Pistia, which is, in fact, a reduced aroideous plant. 
Some of the Aroidee are arborescent, or cling to trees by aérial roots, but the 
majority are herbaceous in nature, and loose in texture, with a colourless or milky, 
generally acrid juice. They abound in tropical parts of the world, but like many other 
families of such a distribution, a few species extend to higher latitudes both north and 
south, especially as they require only a few months to bring them to perfection. They 
are, moreover, furnished with tubers or rhizomes, which from their underground situ- 
ation are easily able to bear the vicissitudes of temperature; thus Arum maculatum is 
found in every part of the British isles, and Calla palustris extends even to 64° north, 
where it inhabits moist situations in Southern Lapland. Richardia (Calla) Athiopica 
is found at the Cape of Good Hope, and Gymnostachys in Eastern extratropical New 
Holland. In America, according to Humboldt, as quoted by Dr. Lindley, their 
principal station is on the submontane region between 1,200 and 3,600 feet of elevation, 
where the climate is temperate, and the rains abundant; in the Andes, Pothos (now 
Anthurium) pedatus and P. quinquenervius, are found at an elevation of 8,400 feet. In 
the Himalayas, Pothos (now Scindaspus) officinalis, extends to elevations of 2,000 
feet in the Kheree Pass in 30° of N. latitude; and species of Arisema are common 
in Nepal on Sheopore, &c., as well as on Mussooree, and other parts of the Himalayas, 
at-7,00) and 8,000 feet of elevation, but chiefly in the rainy season. 
The species fougd in the plains of India, and chiefly in the southern parts, have 
been formed into the genera Cryptocoryne (including the Indian species of Ambrosinia 
of Roxburgh), Zyphonium (Arum trilobatum, orixense, &¢e.), Amorphophallus (Arum cam- 
panulatum), 
